src/pkg/[n-z]*: gofix -r error -force=error R=golang-dev, bsiegert, iant CC=golang-dev https://golang.org/cl/5294074

diff --git a/src/pkg/net/cgo_stub.go b/src/pkg/net/cgo_stub.go
index 565cbe7..fbe6150 100644
--- a/src/pkg/net/cgo_stub.go
+++ b/src/pkg/net/cgo_stub.go

@@ -8,20 +8,18 @@
 
 package net
 
-import "os"
-
-func cgoLookupHost(name string) (addrs []string, err os.Error, completed bool) {
+func cgoLookupHost(name string) (addrs []string, err error, completed bool) {
 	return nil, nil, false
 }
 
-func cgoLookupPort(network, service string) (port int, err os.Error, completed bool) {
+func cgoLookupPort(network, service string) (port int, err error, completed bool) {
 	return 0, nil, false
 }
 
-func cgoLookupIP(name string) (addrs []IP, err os.Error, completed bool) {
+func cgoLookupIP(name string) (addrs []IP, err error, completed bool) {
 	return nil, nil, false
 }
 
-func cgoLookupCNAME(name string) (cname string, err os.Error, completed bool) {
+func cgoLookupCNAME(name string) (cname string, err error, completed bool) {
 	return "", nil, false
 }

diff --git a/src/pkg/net/cgo_unix.go b/src/pkg/net/cgo_unix.go
index ec2a393..36a3f3d 100644
--- a/src/pkg/net/cgo_unix.go
+++ b/src/pkg/net/cgo_unix.go

@@ -18,12 +18,11 @@
 import "C"
 
 import (
-	"os"
 	"syscall"
 	"unsafe"
 )
 
-func cgoLookupHost(name string) (addrs []string, err os.Error, completed bool) {
+func cgoLookupHost(name string) (addrs []string, err error, completed bool) {
 	ip, err, completed := cgoLookupIP(name)
 	for _, p := range ip {
 		addrs = append(addrs, p.String())
@@ -31,7 +30,7 @@
 	return
 }
 
-func cgoLookupPort(net, service string) (port int, err os.Error, completed bool) {
+func cgoLookupPort(net, service string) (port int, err error, completed bool) {
 	var res *C.struct_addrinfo
 	var hints C.struct_addrinfo
 
@@ -78,7 +77,7 @@
 	return 0, &AddrError{"unknown port", net + "/" + service}, true
 }
 
-func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err os.Error, completed bool) {
+func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err error, completed bool) {
 	var res *C.struct_addrinfo
 	var hints C.struct_addrinfo
 
@@ -98,11 +97,11 @@
 		if gerrno == C.EAI_NONAME {
 			str = noSuchHost
 		} else if gerrno == C.EAI_SYSTEM {
-			str = err.String()
+			str = err.Error()
 		} else {
 			str = C.GoString(C.gai_strerror(gerrno))
 		}
-		return nil, "", &DNSError{Error: str, Name: name}, true
+		return nil, "", &DNSError{Err: str, Name: name}, true
 	}
 	defer C.freeaddrinfo(res)
 	if res != nil {
@@ -133,12 +132,12 @@
 	return addrs, cname, nil, true
 }
 
-func cgoLookupIP(name string) (addrs []IP, err os.Error, completed bool) {
+func cgoLookupIP(name string) (addrs []IP, err error, completed bool) {
 	addrs, _, err, completed = cgoLookupIPCNAME(name)
 	return
 }
 
-func cgoLookupCNAME(name string) (cname string, err os.Error, completed bool) {
+func cgoLookupCNAME(name string) (cname string, err error, completed bool) {
 	_, cname, err, completed = cgoLookupIPCNAME(name)
 	return
 }

diff --git a/src/pkg/net/dial.go b/src/pkg/net/dial.go
index 85d54b3..43866dc 100644
--- a/src/pkg/net/dial.go
+++ b/src/pkg/net/dial.go

@@ -4,9 +4,7 @@
 
 package net
 
-import "os"
-
-func resolveNetAddr(op, net, addr string) (a Addr, err os.Error) {
+func resolveNetAddr(op, net, addr string) (a Addr, err error) {
 	if addr == "" {
 		return nil, &OpError{op, net, nil, errMissingAddress}
 	}
@@ -44,7 +42,7 @@
 //	Dial("tcp", "google.com:80")
 //	Dial("tcp", "[de:ad:be:ef::ca:fe]:80")
 //
-func Dial(net, addr string) (c Conn, err os.Error) {
+func Dial(net, addr string) (c Conn, err error) {
 	addri, err := resolveNetAddr("dial", net, addr)
 	if err != nil {
 		return nil, err
@@ -70,7 +68,7 @@
 // Listen announces on the local network address laddr.
 // The network string net must be a stream-oriented
 // network: "tcp", "tcp4", "tcp6", or "unix", or "unixpacket".
-func Listen(net, laddr string) (l Listener, err os.Error) {
+func Listen(net, laddr string) (l Listener, err error) {
 	switch net {
 	case "tcp", "tcp4", "tcp6":
 		var la *TCPAddr
@@ -103,7 +101,7 @@
 // ListenPacket announces on the local network address laddr.
 // The network string net must be a packet-oriented network:
 // "udp", "udp4", "udp6", or "unixgram".
-func ListenPacket(net, laddr string) (c PacketConn, err os.Error) {
+func ListenPacket(net, laddr string) (c PacketConn, err error) {
 	switch net {
 	case "udp", "udp4", "udp6":
 		var la *UDPAddr

diff --git a/src/pkg/net/dict/dict.go b/src/pkg/net/dict/dict.go
index b146ea2..e7f5290 100644
--- a/src/pkg/net/dict/dict.go
+++ b/src/pkg/net/dict/dict.go

@@ -8,7 +8,6 @@
 
 import (
 	"net/textproto"
-	"os"
 	"strconv"
 	"strings"
 )
@@ -20,7 +19,7 @@
 
 // Dial returns a new client connected to a dictionary server at
 // addr on the given network.
-func Dial(network, addr string) (*Client, os.Error) {
+func Dial(network, addr string) (*Client, error) {
 	text, err := textproto.Dial(network, addr)
 	if err != nil {
 		return nil, err
@@ -34,7 +33,7 @@
 }
 
 // Close closes the connection to the dictionary server.
-func (c *Client) Close() os.Error {
+func (c *Client) Close() error {
 	return c.text.Close()
 }
 
@@ -45,7 +44,7 @@
 }
 
 // Dicts returns a list of the dictionaries available on the server.
-func (c *Client) Dicts() ([]Dict, os.Error) {
+func (c *Client) Dicts() ([]Dict, error) {
 	id, err := c.text.Cmd("SHOW DB")
 	if err != nil {
 		return nil, err
@@ -93,7 +92,7 @@
 // The special dictionary name "!" means to look in all the
 // server's dictionaries in turn, stopping after finding the word
 // in one of them.
-func (c *Client) Define(dict, word string) ([]*Defn, os.Error) {
+func (c *Client) Define(dict, word string) ([]*Defn, error) {
 	id, err := c.text.Cmd("DEFINE %s %q", dict, word)
 	if err != nil {
 		return nil, err
@@ -142,7 +141,7 @@
 // Fields returns the fields in s.
 // Fields are space separated unquoted words
 // or quoted with single or double quote.
-func fields(s string) ([]string, os.Error) {
+func fields(s string) ([]string, error) {
 	var v []string
 	i := 0
 	for {

diff --git a/src/pkg/net/dnsclient.go b/src/pkg/net/dnsclient.go
index 93c04f6..e66f28c 100644
--- a/src/pkg/net/dnsclient.go
+++ b/src/pkg/net/dnsclient.go

@@ -7,20 +7,19 @@
 import (
 	"bytes"
 	"fmt"
-	"os"
 	"rand"
 	"sort"
 )
 
 // DNSError represents a DNS lookup error.
 type DNSError struct {
-	Error     string // description of the error
+	Err       string // description of the error
 	Name      string // name looked for
 	Server    string // server used
 	IsTimeout bool
 }
 
-func (e *DNSError) String() string {
+func (e *DNSError) Error() string {
 	if e == nil {
 		return "<nil>"
 	}
@@ -28,7 +27,7 @@
 	if e.Server != "" {
 		s += " on " + e.Server
 	}
-	s += ": " + e.Error
+	s += ": " + e.Err
 	return s
 }
 
@@ -40,10 +39,10 @@
 // reverseaddr returns the in-addr.arpa. or ip6.arpa. hostname of the IP
 // address addr suitable for rDNS (PTR) record lookup or an error if it fails
 // to parse the IP address.
-func reverseaddr(addr string) (arpa string, err os.Error) {
+func reverseaddr(addr string) (arpa string, err error) {
 	ip := ParseIP(addr)
 	if ip == nil {
-		return "", &DNSError{Error: "unrecognized address", Name: addr}
+		return "", &DNSError{Err: "unrecognized address", Name: addr}
 	}
 	if ip.To4() != nil {
 		return fmt.Sprintf("%d.%d.%d.%d.in-addr.arpa.", ip[15], ip[14], ip[13], ip[12]), nil
@@ -64,18 +63,18 @@
 
 // Find answer for name in dns message.
 // On return, if err == nil, addrs != nil.
-func answer(name, server string, dns *dnsMsg, qtype uint16) (cname string, addrs []dnsRR, err os.Error) {
+func answer(name, server string, dns *dnsMsg, qtype uint16) (cname string, addrs []dnsRR, err error) {
 	addrs = make([]dnsRR, 0, len(dns.answer))
 
 	if dns.rcode == dnsRcodeNameError && dns.recursion_available {
-		return "", nil, &DNSError{Error: noSuchHost, Name: name}
+		return "", nil, &DNSError{Err: noSuchHost, Name: name}
 	}
 	if dns.rcode != dnsRcodeSuccess {
 		// None of the error codes make sense
 		// for the query we sent.  If we didn't get
 		// a name error and we didn't get success,
 		// the server is behaving incorrectly.
-		return "", nil, &DNSError{Error: "server misbehaving", Name: name, Server: server}
+		return "", nil, &DNSError{Err: "server misbehaving", Name: name, Server: server}
 	}
 
 	// Look for the name.
@@ -107,12 +106,12 @@
 			}
 		}
 		if len(addrs) == 0 {
-			return "", nil, &DNSError{Error: noSuchHost, Name: name, Server: server}
+			return "", nil, &DNSError{Err: noSuchHost, Name: name, Server: server}
 		}
 		return name, addrs, nil
 	}
 
-	return "", nil, &DNSError{Error: "too many redirects", Name: name, Server: server}
+	return "", nil, &DNSError{Err: "too many redirects", Name: name, Server: server}
 }
 
 func isDomainName(s string) bool {

diff --git a/src/pkg/net/dnsclient_unix.go b/src/pkg/net/dnsclient_unix.go
index eb7db5e..e321ed9 100644
--- a/src/pkg/net/dnsclient_unix.go
+++ b/src/pkg/net/dnsclient_unix.go

@@ -17,7 +17,6 @@
 package net
 
 import (
-	"os"
 	"rand"
 	"sync"
 	"time"
@@ -25,9 +24,9 @@
 
 // Send a request on the connection and hope for a reply.
 // Up to cfg.attempts attempts.
-func exchange(cfg *dnsConfig, c Conn, name string, qtype uint16) (*dnsMsg, os.Error) {
+func exchange(cfg *dnsConfig, c Conn, name string, qtype uint16) (*dnsMsg, error) {
 	if len(name) >= 256 {
-		return nil, &DNSError{Error: "name too long", Name: name}
+		return nil, &DNSError{Err: "name too long", Name: name}
 	}
 	out := new(dnsMsg)
 	out.id = uint16(rand.Int()) ^ uint16(time.Nanoseconds())
@@ -37,7 +36,7 @@
 	out.recursion_desired = true
 	msg, ok := out.Pack()
 	if !ok {
-		return nil, &DNSError{Error: "internal error - cannot pack message", Name: name}
+		return nil, &DNSError{Err: "internal error - cannot pack message", Name: name}
 	}
 
 	for attempt := 0; attempt < cfg.attempts; attempt++ {
@@ -67,14 +66,14 @@
 	if a := c.RemoteAddr(); a != nil {
 		server = a.String()
 	}
-	return nil, &DNSError{Error: "no answer from server", Name: name, Server: server, IsTimeout: true}
+	return nil, &DNSError{Err: "no answer from server", Name: name, Server: server, IsTimeout: true}
 }
 
 // Do a lookup for a single name, which must be rooted
 // (otherwise answer will not find the answers).
-func tryOneName(cfg *dnsConfig, name string, qtype uint16) (cname string, addrs []dnsRR, err os.Error) {
+func tryOneName(cfg *dnsConfig, name string, qtype uint16) (cname string, addrs []dnsRR, err error) {
 	if len(cfg.servers) == 0 {
-		return "", nil, &DNSError{Error: "no DNS servers", Name: name}
+		return "", nil, &DNSError{Err: "no DNS servers", Name: name}
 	}
 	for i := 0; i < len(cfg.servers); i++ {
 		// Calling Dial here is scary -- we have to be sure
@@ -96,7 +95,7 @@
 			continue
 		}
 		cname, addrs, err = answer(name, server, msg, qtype)
-		if err == nil || err.(*DNSError).Error == noSuchHost {
+		if err == nil || err.(*DNSError).Err == noSuchHost {
 			break
 		}
 	}
@@ -123,15 +122,15 @@
 }
 
 var cfg *dnsConfig
-var dnserr os.Error
+var dnserr error
 
 func loadConfig() { cfg, dnserr = dnsReadConfig() }
 
 var onceLoadConfig sync.Once
 
-func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err os.Error) {
+func lookup(name string, qtype uint16) (cname string, addrs []dnsRR, err error) {
 	if !isDomainName(name) {
-		return name, nil, &DNSError{Error: "invalid domain name", Name: name}
+		return name, nil, &DNSError{Err: "invalid domain name", Name: name}
 	}
 	onceLoadConfig.Do(loadConfig)
 	if dnserr != nil || cfg == nil {
@@ -186,7 +185,7 @@
 // Normally we let cgo use the C library resolver instead of
 // depending on our lookup code, so that Go and C get the same
 // answers.
-func goLookupHost(name string) (addrs []string, err os.Error) {
+func goLookupHost(name string) (addrs []string, err error) {
 	// Use entries from /etc/hosts if they match.
 	addrs = lookupStaticHost(name)
 	if len(addrs) > 0 {
@@ -214,7 +213,7 @@
 // Normally we let cgo use the C library resolver instead of
 // depending on our lookup code, so that Go and C get the same
 // answers.
-func goLookupIP(name string) (addrs []IP, err os.Error) {
+func goLookupIP(name string) (addrs []IP, err error) {
 	// Use entries from /etc/hosts if possible.
 	haddrs := lookupStaticHost(name)
 	if len(haddrs) > 0 {
@@ -260,7 +259,7 @@
 // Normally we let cgo use the C library resolver instead of
 // depending on our lookup code, so that Go and C get the same
 // answers.
-func goLookupCNAME(name string) (cname string, err os.Error) {
+func goLookupCNAME(name string) (cname string, err error) {
 	onceLoadConfig.Do(loadConfig)
 	if dnserr != nil || cfg == nil {
 		err = dnserr

diff --git a/src/pkg/net/dnsconfig.go b/src/pkg/net/dnsconfig.go
index afc0599..379fec9 100644
--- a/src/pkg/net/dnsconfig.go
+++ b/src/pkg/net/dnsconfig.go

@@ -8,8 +8,6 @@
 
 package net
 
-import "os"
-
 type dnsConfig struct {
 	servers  []string // servers to use
 	search   []string // suffixes to append to local name
@@ -19,14 +17,14 @@
 	rotate   bool     // round robin among servers
 }
 
-var dnsconfigError os.Error
+var dnsconfigError error
 
 type DNSConfigError struct {
-	Error os.Error
+	Err error
 }
 
-func (e *DNSConfigError) String() string {
-	return "error reading DNS config: " + e.Error.String()
+func (e *DNSConfigError) Error() string {
+	return "error reading DNS config: " + e.Err.Error()
 }
 
 func (e *DNSConfigError) Timeout() bool   { return false }
@@ -36,7 +34,7 @@
 // TODO(rsc): Supposed to call uname() and chop the beginning
 // of the host name to get the default search domain.
 // We assume it's in resolv.conf anyway.
-func dnsReadConfig() (*dnsConfig, os.Error) {
+func dnsReadConfig() (*dnsConfig, error) {
 	file, err := open("/etc/resolv.conf")
 	if err != nil {
 		return nil, &DNSConfigError{err}

diff --git a/src/pkg/net/fd.go b/src/pkg/net/fd.go
index 80d40af..025075d 100644
--- a/src/pkg/net/fd.go
+++ b/src/pkg/net/fd.go

@@ -46,7 +46,7 @@
 
 type InvalidConnError struct{}
 
-func (e *InvalidConnError) String() string  { return "invalid net.Conn" }
+func (e *InvalidConnError) Error() string   { return "invalid net.Conn" }
 func (e *InvalidConnError) Temporary() bool { return false }
 func (e *InvalidConnError) Timeout() bool   { return false }
 
@@ -126,7 +126,7 @@
 
 	wake, err := s.poll.AddFD(intfd, mode, false)
 	if err != nil {
-		panic("pollServer AddFD " + err.String())
+		panic("pollServer AddFD " + err.Error())
 	}
 	if wake {
 		doWakeup = true
@@ -227,7 +227,7 @@
 		}
 		fd, mode, err := s.poll.WaitFD(s, t)
 		if err != nil {
-			print("pollServer WaitFD: ", err.String(), "\n")
+			print("pollServer WaitFD: ", err.Error(), "\n")
 			return
 		}
 		if fd < 0 {
@@ -271,12 +271,12 @@
 func startServer() {
 	p, err := newPollServer()
 	if err != nil {
-		print("Start pollServer: ", err.String(), "\n")
+		print("Start pollServer: ", err.Error(), "\n")
 	}
 	pollserver = p
 }
 
-func newFD(fd, family, proto int, net string) (f *netFD, err os.Error) {
+func newFD(fd, family, proto int, net string) (f *netFD, err error) {
 	onceStartServer.Do(startServer)
 	if e := syscall.SetNonblock(fd, true); e != 0 {
 		return nil, os.Errno(e)
@@ -305,7 +305,7 @@
 	fd.sysfile = os.NewFile(fd.sysfd, fd.net+":"+ls+"->"+rs)
 }
 
-func (fd *netFD) connect(ra syscall.Sockaddr) (err os.Error) {
+func (fd *netFD) connect(ra syscall.Sockaddr) (err error) {
 	e := syscall.Connect(fd.sysfd, ra)
 	if e == syscall.EINPROGRESS {
 		var errno int
@@ -346,7 +346,7 @@
 	fd.sysmu.Unlock()
 }
 
-func (fd *netFD) Close() os.Error {
+func (fd *netFD) Close() error {
 	if fd == nil || fd.sysfile == nil {
 		return os.EINVAL
 	}
@@ -358,7 +358,7 @@
 	return nil
 }
 
-func (fd *netFD) shutdown(how int) os.Error {
+func (fd *netFD) shutdown(how int) error {
 	if fd == nil || fd.sysfile == nil {
 		return os.EINVAL
 	}
@@ -369,15 +369,15 @@
 	return nil
 }
 
-func (fd *netFD) CloseRead() os.Error {
+func (fd *netFD) CloseRead() error {
 	return fd.shutdown(syscall.SHUT_RD)
 }
 
-func (fd *netFD) CloseWrite() os.Error {
+func (fd *netFD) CloseWrite() error {
 	return fd.shutdown(syscall.SHUT_WR)
 }
 
-func (fd *netFD) Read(p []byte) (n int, err os.Error) {
+func (fd *netFD) Read(p []byte) (n int, err error) {
 	if fd == nil {
 		return 0, os.EINVAL
 	}
@@ -393,7 +393,7 @@
 	} else {
 		fd.rdeadline = 0
 	}
-	var oserr os.Error
+	var oserr error
 	for {
 		var errno int
 		n, errno = syscall.Read(fd.sysfile.Fd(), p)
@@ -405,7 +405,7 @@
 			n = 0
 			oserr = os.Errno(errno)
 		} else if n == 0 && errno == 0 && fd.proto != syscall.SOCK_DGRAM {
-			err = os.EOF
+			err = io.EOF
 		}
 		break
 	}
@@ -415,7 +415,7 @@
 	return
 }
 
-func (fd *netFD) ReadFrom(p []byte) (n int, sa syscall.Sockaddr, err os.Error) {
+func (fd *netFD) ReadFrom(p []byte) (n int, sa syscall.Sockaddr, err error) {
 	if fd == nil || fd.sysfile == nil {
 		return 0, nil, os.EINVAL
 	}
@@ -428,7 +428,7 @@
 	} else {
 		fd.rdeadline = 0
 	}
-	var oserr os.Error
+	var oserr error
 	for {
 		var errno int
 		n, sa, errno = syscall.Recvfrom(fd.sysfd, p, 0)
@@ -448,7 +448,7 @@
 	return
 }
 
-func (fd *netFD) ReadMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.Sockaddr, err os.Error) {
+func (fd *netFD) ReadMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.Sockaddr, err error) {
 	if fd == nil || fd.sysfile == nil {
 		return 0, 0, 0, nil, os.EINVAL
 	}
@@ -461,7 +461,7 @@
 	} else {
 		fd.rdeadline = 0
 	}
-	var oserr os.Error
+	var oserr error
 	for {
 		var errno int
 		n, oobn, flags, sa, errno = syscall.Recvmsg(fd.sysfd, p, oob, 0)
@@ -473,7 +473,7 @@
 			oserr = os.Errno(errno)
 		}
 		if n == 0 {
-			oserr = os.EOF
+			oserr = io.EOF
 		}
 		break
 	}
@@ -484,7 +484,7 @@
 	return
 }
 
-func (fd *netFD) Write(p []byte) (n int, err os.Error) {
+func (fd *netFD) Write(p []byte) (n int, err error) {
 	if fd == nil {
 		return 0, os.EINVAL
 	}
@@ -501,7 +501,7 @@
 		fd.wdeadline = 0
 	}
 	nn := 0
-	var oserr os.Error
+	var oserr error
 
 	for {
 		n, errno := syscall.Write(fd.sysfile.Fd(), p[nn:])
@@ -531,7 +531,7 @@
 	return nn, err
 }
 
-func (fd *netFD) WriteTo(p []byte, sa syscall.Sockaddr) (n int, err os.Error) {
+func (fd *netFD) WriteTo(p []byte, sa syscall.Sockaddr) (n int, err error) {
 	if fd == nil || fd.sysfile == nil {
 		return 0, os.EINVAL
 	}
@@ -544,7 +544,7 @@
 	} else {
 		fd.wdeadline = 0
 	}
-	var oserr os.Error
+	var oserr error
 	for {
 		errno := syscall.Sendto(fd.sysfd, p, 0, sa)
 		if errno == syscall.EAGAIN && fd.wdeadline >= 0 {
@@ -564,7 +564,7 @@
 	return
 }
 
-func (fd *netFD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err os.Error) {
+func (fd *netFD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err error) {
 	if fd == nil || fd.sysfile == nil {
 		return 0, 0, os.EINVAL
 	}
@@ -577,7 +577,7 @@
 	} else {
 		fd.wdeadline = 0
 	}
-	var oserr os.Error
+	var oserr error
 	for {
 		var errno int
 		errno = syscall.Sendmsg(fd.sysfd, p, oob, sa, 0)
@@ -599,7 +599,7 @@
 	return
 }
 
-func (fd *netFD) accept(toAddr func(syscall.Sockaddr) Addr) (nfd *netFD, err os.Error) {
+func (fd *netFD) accept(toAddr func(syscall.Sockaddr) Addr) (nfd *netFD, err error) {
 	if fd == nil || fd.sysfile == nil {
 		return nil, os.EINVAL
 	}
@@ -647,7 +647,7 @@
 	return nfd, nil
 }
 
-func (fd *netFD) dup() (f *os.File, err os.Error) {
+func (fd *netFD) dup() (f *os.File, err error) {
 	ns, e := syscall.Dup(fd.sysfd)
 	if e != 0 {
 		return nil, &OpError{"dup", fd.net, fd.laddr, os.Errno(e)}

diff --git a/src/pkg/net/fd_darwin.go b/src/pkg/net/fd_darwin.go
index 7e3d549..c25a510 100644
--- a/src/pkg/net/fd_darwin.go
+++ b/src/pkg/net/fd_darwin.go

@@ -7,6 +7,7 @@
 package net
 
 import (
+	"errors"
 	"os"
 	"syscall"
 )
@@ -21,7 +22,7 @@
 	kbuf [1]syscall.Kevent_t
 }
 
-func newpollster() (p *pollster, err os.Error) {
+func newpollster() (p *pollster, err error) {
 	p = new(pollster)
 	var e int
 	if p.kq, e = syscall.Kqueue(); e != 0 {
@@ -31,7 +32,7 @@
 	return p, nil
 }
 
-func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, os.Error) {
+func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, error) {
 	// pollServer is locked.
 
 	var kmode int
@@ -56,7 +57,7 @@
 		return false, os.NewSyscallError("kevent", e)
 	}
 	if n != 1 || (ev.Flags&syscall.EV_ERROR) == 0 || int(ev.Ident) != fd || int(ev.Filter) != kmode {
-		return false, os.NewError("kqueue phase error")
+		return false, errors.New("kqueue phase error")
 	}
 	if ev.Data != 0 {
 		return false, os.Errno(int(ev.Data))
@@ -81,7 +82,7 @@
 	syscall.Kevent(p.kq, p.kbuf[0:], p.kbuf[0:], nil)
 }
 
-func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err os.Error) {
+func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err error) {
 	var t *syscall.Timespec
 	for len(p.events) == 0 {
 		if nsec > 0 {
@@ -117,4 +118,4 @@
 	return fd, mode, nil
 }
 
-func (p *pollster) Close() os.Error { return os.NewSyscallError("close", syscall.Close(p.kq)) }
+func (p *pollster) Close() error { return os.NewSyscallError("close", syscall.Close(p.kq)) }

diff --git a/src/pkg/net/fd_freebsd.go b/src/pkg/net/fd_freebsd.go
index e50883e..f61008a 100644
--- a/src/pkg/net/fd_freebsd.go
+++ b/src/pkg/net/fd_freebsd.go

@@ -21,7 +21,7 @@
 	kbuf [1]syscall.Kevent_t
 }
 
-func newpollster() (p *pollster, err os.Error) {
+func newpollster() (p *pollster, err error) {
 	p = new(pollster)
 	var e int
 	if p.kq, e = syscall.Kqueue(); e != 0 {
@@ -31,7 +31,7 @@
 	return p, nil
 }
 
-func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, os.Error) {
+func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, error) {
 	// pollServer is locked.
 
 	var kmode int
@@ -77,7 +77,7 @@
 	syscall.Kevent(p.kq, p.kbuf[:], nil, nil)
 }
 
-func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err os.Error) {
+func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err error) {
 	var t *syscall.Timespec
 	for len(p.events) == 0 {
 		if nsec > 0 {
@@ -113,4 +113,4 @@
 	return fd, mode, nil
 }
 
-func (p *pollster) Close() os.Error { return os.NewSyscallError("close", syscall.Close(p.kq)) }
+func (p *pollster) Close() error { return os.NewSyscallError("close", syscall.Close(p.kq)) }

diff --git a/src/pkg/net/fd_linux.go b/src/pkg/net/fd_linux.go
index c860c84..56c6a28 100644
--- a/src/pkg/net/fd_linux.go
+++ b/src/pkg/net/fd_linux.go

@@ -33,7 +33,7 @@
 	ctlEvent syscall.EpollEvent
 }
 
-func newpollster() (p *pollster, err os.Error) {
+func newpollster() (p *pollster, err error) {
 	p = new(pollster)
 	var e int
 
@@ -47,7 +47,7 @@
 	return p, nil
 }
 
-func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, os.Error) {
+func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, error) {
 	// pollServer is locked.
 
 	var already bool
@@ -130,7 +130,7 @@
 	}
 }
 
-func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err os.Error) {
+func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err error) {
 	for len(p.waitEvents) == 0 {
 		var msec int = -1
 		if nsec > 0 {
@@ -177,6 +177,6 @@
 	return fd, 'r', nil
 }
 
-func (p *pollster) Close() os.Error {
+func (p *pollster) Close() error {
 	return os.NewSyscallError("close", syscall.Close(p.epfd))
 }

diff --git a/src/pkg/net/fd_openbsd.go b/src/pkg/net/fd_openbsd.go
index e50883e..f61008a 100644
--- a/src/pkg/net/fd_openbsd.go
+++ b/src/pkg/net/fd_openbsd.go

@@ -21,7 +21,7 @@
 	kbuf [1]syscall.Kevent_t
 }
 
-func newpollster() (p *pollster, err os.Error) {
+func newpollster() (p *pollster, err error) {
 	p = new(pollster)
 	var e int
 	if p.kq, e = syscall.Kqueue(); e != 0 {
@@ -31,7 +31,7 @@
 	return p, nil
 }
 
-func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, os.Error) {
+func (p *pollster) AddFD(fd int, mode int, repeat bool) (bool, error) {
 	// pollServer is locked.
 
 	var kmode int
@@ -77,7 +77,7 @@
 	syscall.Kevent(p.kq, p.kbuf[:], nil, nil)
 }
 
-func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err os.Error) {
+func (p *pollster) WaitFD(s *pollServer, nsec int64) (fd int, mode int, err error) {
 	var t *syscall.Timespec
 	for len(p.events) == 0 {
 		if nsec > 0 {
@@ -113,4 +113,4 @@
 	return fd, mode, nil
 }
 
-func (p *pollster) Close() os.Error { return os.NewSyscallError("close", syscall.Close(p.kq)) }
+func (p *pollster) Close() error { return os.NewSyscallError("close", syscall.Close(p.kq)) }

diff --git a/src/pkg/net/fd_windows.go b/src/pkg/net/fd_windows.go
index 8e8b3b7..ce228e9 100644
--- a/src/pkg/net/fd_windows.go
+++ b/src/pkg/net/fd_windows.go

@@ -5,6 +5,7 @@
 package net
 
 import (
+	"io"
 	"os"
 	"runtime"
 	"sync"
@@ -15,11 +16,11 @@
 
 type InvalidConnError struct{}
 
-func (e *InvalidConnError) String() string  { return "invalid net.Conn" }
+func (e *InvalidConnError) Error() string   { return "invalid net.Conn" }
 func (e *InvalidConnError) Temporary() bool { return false }
 func (e *InvalidConnError) Timeout() bool   { return false }
 
-var initErr os.Error
+var initErr error
 
 func init() {
 	var d syscall.WSAData
@@ -151,7 +152,7 @@
 // ExecIO executes a single io operation. It either executes it
 // inline, or, if timeouts are employed, passes the request onto
 // a special goroutine and waits for completion or cancels request.
-func (s *ioSrv) ExecIO(oi anOpIface, deadline_delta int64) (n int, err os.Error) {
+func (s *ioSrv) ExecIO(oi anOpIface, deadline_delta int64) (n int, err error) {
 	var e int
 	o := oi.Op()
 	if deadline_delta > 0 {
@@ -249,7 +250,7 @@
 	return f
 }
 
-func newFD(fd syscall.Handle, family, proto int, net string) (f *netFD, err os.Error) {
+func newFD(fd syscall.Handle, family, proto int, net string) (f *netFD, err error) {
 	if initErr != nil {
 		return nil, initErr
 	}
@@ -266,7 +267,7 @@
 	fd.raddr = raddr
 }
 
-func (fd *netFD) connect(ra syscall.Sockaddr) (err os.Error) {
+func (fd *netFD) connect(ra syscall.Sockaddr) (err error) {
 	e := syscall.Connect(fd.sysfd, ra)
 	if e != 0 {
 		return os.Errno(e)
@@ -300,7 +301,7 @@
 	fd.sysmu.Unlock()
 }
 
-func (fd *netFD) Close() os.Error {
+func (fd *netFD) Close() error {
 	if fd == nil || fd.sysfd == syscall.InvalidHandle {
 		return os.EINVAL
 	}
@@ -312,7 +313,7 @@
 	return nil
 }
 
-func (fd *netFD) shutdown(how int) os.Error {
+func (fd *netFD) shutdown(how int) error {
 	if fd == nil || fd.sysfd == syscall.InvalidHandle {
 		return os.EINVAL
 	}
@@ -323,11 +324,11 @@
 	return nil
 }
 
-func (fd *netFD) CloseRead() os.Error {
+func (fd *netFD) CloseRead() error {
 	return fd.shutdown(syscall.SHUT_RD)
 }
 
-func (fd *netFD) CloseWrite() os.Error {
+func (fd *netFD) CloseWrite() error {
 	return fd.shutdown(syscall.SHUT_WR)
 }
 
@@ -346,7 +347,7 @@
 	return "WSARecv"
 }
 
-func (fd *netFD) Read(buf []byte) (n int, err os.Error) {
+func (fd *netFD) Read(buf []byte) (n int, err error) {
 	if fd == nil {
 		return 0, os.EINVAL
 	}
@@ -361,7 +362,7 @@
 	o.Init(fd, buf, 'r')
 	n, err = iosrv.ExecIO(&o, fd.rdeadline_delta)
 	if err == nil && n == 0 {
-		err = os.EOF
+		err = io.EOF
 	}
 	return
 }
@@ -383,7 +384,7 @@
 	return "WSARecvFrom"
 }
 
-func (fd *netFD) ReadFrom(buf []byte) (n int, sa syscall.Sockaddr, err os.Error) {
+func (fd *netFD) ReadFrom(buf []byte) (n int, sa syscall.Sockaddr, err error) {
 	if fd == nil {
 		return 0, nil, os.EINVAL
 	}
@@ -423,7 +424,7 @@
 	return "WSASend"
 }
 
-func (fd *netFD) Write(buf []byte) (n int, err os.Error) {
+func (fd *netFD) Write(buf []byte) (n int, err error) {
 	if fd == nil {
 		return 0, os.EINVAL
 	}
@@ -455,7 +456,7 @@
 	return "WSASendto"
 }
 
-func (fd *netFD) WriteTo(buf []byte, sa syscall.Sockaddr) (n int, err os.Error) {
+func (fd *netFD) WriteTo(buf []byte, sa syscall.Sockaddr) (n int, err error) {
 	if fd == nil {
 		return 0, os.EINVAL
 	}
@@ -494,7 +495,7 @@
 	return "AcceptEx"
 }
 
-func (fd *netFD) accept(toAddr func(syscall.Sockaddr) Addr) (nfd *netFD, err os.Error) {
+func (fd *netFD) accept(toAddr func(syscall.Sockaddr) Addr) (nfd *netFD, err error) {
 	if fd == nil || fd.sysfd == syscall.InvalidHandle {
 		return nil, os.EINVAL
 	}
@@ -551,15 +552,15 @@
 
 // Unimplemented functions.
 
-func (fd *netFD) dup() (f *os.File, err os.Error) {
+func (fd *netFD) dup() (f *os.File, err error) {
 	// TODO: Implement this
 	return nil, os.NewSyscallError("dup", syscall.EWINDOWS)
 }
 
-func (fd *netFD) ReadMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.Sockaddr, err os.Error) {
+func (fd *netFD) ReadMsg(p []byte, oob []byte) (n, oobn, flags int, sa syscall.Sockaddr, err error) {
 	return 0, 0, 0, nil, os.EAFNOSUPPORT
 }
 
-func (fd *netFD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err os.Error) {
+func (fd *netFD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err error) {
 	return 0, 0, os.EAFNOSUPPORT
 }

diff --git a/src/pkg/net/file.go b/src/pkg/net/file.go
index ed2559d..0ad869d 100644
--- a/src/pkg/net/file.go
+++ b/src/pkg/net/file.go

@@ -11,7 +11,7 @@
 	"syscall"
 )
 
-func newFileFD(f *os.File) (nfd *netFD, err os.Error) {
+func newFileFD(f *os.File) (nfd *netFD, err error) {
 	fd, errno := syscall.Dup(f.Fd())
 	if errno != 0 {
 		return nil, os.NewSyscallError("dup", errno)
@@ -67,7 +67,7 @@
 // the open file f.  It is the caller's responsibility to close f when
 // finished.  Closing c does not affect f, and closing f does not
 // affect c.
-func FileConn(f *os.File) (c Conn, err os.Error) {
+func FileConn(f *os.File) (c Conn, err error) {
 	fd, err := newFileFD(f)
 	if err != nil {
 		return nil, err
@@ -90,7 +90,7 @@
 // to the open file f.  It is the caller's responsibility to close l
 // when finished.  Closing c does not affect l, and closing l does not
 // affect c.
-func FileListener(f *os.File) (l Listener, err os.Error) {
+func FileListener(f *os.File) (l Listener, err error) {
 	fd, err := newFileFD(f)
 	if err != nil {
 		return nil, err
@@ -109,7 +109,7 @@
 // corresponding to the open file f.  It is the caller's
 // responsibility to close f when finished.  Closing c does not affect
 // f, and closing f does not affect c.
-func FilePacketConn(f *os.File) (c PacketConn, err os.Error) {
+func FilePacketConn(f *os.File) (c PacketConn, err error) {
 	fd, err := newFileFD(f)
 	if err != nil {
 		return nil, err

diff --git a/src/pkg/net/file_plan9.go b/src/pkg/net/file_plan9.go
index a07e743..06d7cc8 100644
--- a/src/pkg/net/file_plan9.go
+++ b/src/pkg/net/file_plan9.go

@@ -12,7 +12,7 @@
 // the open file f.  It is the caller's responsibility to close f when
 // finished.  Closing c does not affect f, and closing f does not
 // affect c.
-func FileConn(f *os.File) (c Conn, err os.Error) {
+func FileConn(f *os.File) (c Conn, err error) {
 	return nil, os.EPLAN9
 }
 
@@ -20,7 +20,7 @@
 // to the open file f.  It is the caller's responsibility to close l
 // when finished.  Closing c does not affect l, and closing l does not
 // affect c.
-func FileListener(f *os.File) (l Listener, err os.Error) {
+func FileListener(f *os.File) (l Listener, err error) {
 	return nil, os.EPLAN9
 }
 
@@ -28,6 +28,6 @@
 // corresponding to the open file f.  It is the caller's
 // responsibility to close f when finished.  Closing c does not affect
 // f, and closing f does not affect c.
-func FilePacketConn(f *os.File) (c PacketConn, err os.Error) {
+func FilePacketConn(f *os.File) (c PacketConn, err error) {
 	return nil, os.EPLAN9
 }

diff --git a/src/pkg/net/file_test.go b/src/pkg/net/file_test.go
index 0fa6740..7867fa8 100644
--- a/src/pkg/net/file_test.go
+++ b/src/pkg/net/file_test.go

@@ -14,17 +14,17 @@
 
 type listenerFile interface {
 	Listener
-	File() (f *os.File, err os.Error)
+	File() (f *os.File, err error)
 }
 
 type packetConnFile interface {
 	PacketConn
-	File() (f *os.File, err os.Error)
+	File() (f *os.File, err error)
 }
 
 type connFile interface {
 	Conn
-	File() (f *os.File, err os.Error)
+	File() (f *os.File, err error)
 }
 
 func testFileListener(t *testing.T, net, laddr string) {

diff --git a/src/pkg/net/file_windows.go b/src/pkg/net/file_windows.go
index 94aa583..c50c32e 100644
--- a/src/pkg/net/file_windows.go
+++ b/src/pkg/net/file_windows.go

@@ -9,17 +9,17 @@
 	"syscall"
 )
 
-func FileConn(f *os.File) (c Conn, err os.Error) {
+func FileConn(f *os.File) (c Conn, err error) {
 	// TODO: Implement this
 	return nil, os.NewSyscallError("FileConn", syscall.EWINDOWS)
 }
 
-func FileListener(f *os.File) (l Listener, err os.Error) {
+func FileListener(f *os.File) (l Listener, err error) {
 	// TODO: Implement this
 	return nil, os.NewSyscallError("FileListener", syscall.EWINDOWS)
 }
 
-func FilePacketConn(f *os.File) (c PacketConn, err os.Error) {
+func FilePacketConn(f *os.File) (c PacketConn, err error) {
 	// TODO: Implement this
 	return nil, os.NewSyscallError("FilePacketConn", syscall.EWINDOWS)
 }

diff --git a/src/pkg/net/interface.go b/src/pkg/net/interface.go
index 2696b7f..95486a6 100644
--- a/src/pkg/net/interface.go
+++ b/src/pkg/net/interface.go

@@ -8,8 +8,8 @@
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
-	"os"
 )
 
 // A HardwareAddr represents a physical hardware address.
@@ -34,7 +34,7 @@
 //   01-23-45-67-89-ab-cd-ef
 //   0123.4567.89ab
 //   0123.4567.89ab.cdef
-func ParseMAC(s string) (hw HardwareAddr, err os.Error) {
+func ParseMAC(s string) (hw HardwareAddr, err error) {
 	if len(s) < 14 {
 		goto error
 	}
@@ -80,7 +80,7 @@
 	return hw, nil
 
 error:
-	return nil, os.NewError("invalid MAC address: " + s)
+	return nil, errors.New("invalid MAC address: " + s)
 }
 
 // Interface represents a mapping between network interface name
@@ -129,37 +129,37 @@
 }
 
 // Addrs returns interface addresses for a specific interface.
-func (ifi *Interface) Addrs() ([]Addr, os.Error) {
+func (ifi *Interface) Addrs() ([]Addr, error) {
 	if ifi == nil {
-		return nil, os.NewError("net: invalid interface")
+		return nil, errors.New("net: invalid interface")
 	}
 	return interfaceAddrTable(ifi.Index)
 }
 
 // MulticastAddrs returns multicast, joined group addresses for
 // a specific interface.
-func (ifi *Interface) MulticastAddrs() ([]Addr, os.Error) {
+func (ifi *Interface) MulticastAddrs() ([]Addr, error) {
 	if ifi == nil {
-		return nil, os.NewError("net: invalid interface")
+		return nil, errors.New("net: invalid interface")
 	}
 	return interfaceMulticastAddrTable(ifi.Index)
 }
 
 // Interfaces returns a list of the systems's network interfaces.
-func Interfaces() ([]Interface, os.Error) {
+func Interfaces() ([]Interface, error) {
 	return interfaceTable(0)
 }
 
 // InterfaceAddrs returns a list of the system's network interface
 // addresses.
-func InterfaceAddrs() ([]Addr, os.Error) {
+func InterfaceAddrs() ([]Addr, error) {
 	return interfaceAddrTable(0)
 }
 
 // InterfaceByIndex returns the interface specified by index.
-func InterfaceByIndex(index int) (*Interface, os.Error) {
+func InterfaceByIndex(index int) (*Interface, error) {
 	if index <= 0 {
-		return nil, os.NewError("net: invalid interface index")
+		return nil, errors.New("net: invalid interface index")
 	}
 	ift, err := interfaceTable(index)
 	if err != nil {
@@ -168,13 +168,13 @@
 	for _, ifi := range ift {
 		return &ifi, nil
 	}
-	return nil, os.NewError("net: no such interface")
+	return nil, errors.New("net: no such interface")
 }
 
 // InterfaceByName returns the interface specified by name.
-func InterfaceByName(name string) (*Interface, os.Error) {
+func InterfaceByName(name string) (*Interface, error) {
 	if name == "" {
-		return nil, os.NewError("net: invalid interface name")
+		return nil, errors.New("net: invalid interface name")
 	}
 	ift, err := interfaceTable(0)
 	if err != nil {
@@ -185,5 +185,5 @@
 			return &ifi, nil
 		}
 	}
-	return nil, os.NewError("net: no such interface")
+	return nil, errors.New("net: no such interface")
 }

diff --git a/src/pkg/net/interface_bsd.go b/src/pkg/net/interface_bsd.go
index 54fa5dd..b026e01 100644
--- a/src/pkg/net/interface_bsd.go
+++ b/src/pkg/net/interface_bsd.go

@@ -17,7 +17,7 @@
 // If the ifindex is zero, interfaceTable returns mappings of all
 // network interfaces.  Otheriwse it returns a mapping of a specific
 // interface.
-func interfaceTable(ifindex int) ([]Interface, os.Error) {
+func interfaceTable(ifindex int) ([]Interface, error) {
 	var (
 		tab  []byte
 		e    int
@@ -51,7 +51,7 @@
 	return ift, nil
 }
 
-func newLink(m *syscall.InterfaceMessage) ([]Interface, os.Error) {
+func newLink(m *syscall.InterfaceMessage) ([]Interface, error) {
 	var ift []Interface
 
 	sas, e := syscall.ParseRoutingSockaddr(m)
@@ -107,7 +107,7 @@
 // If the ifindex is zero, interfaceAddrTable returns addresses
 // for all network interfaces.  Otherwise it returns addresses
 // for a specific interface.
-func interfaceAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceAddrTable(ifindex int) ([]Addr, error) {
 	var (
 		tab  []byte
 		e    int
@@ -141,7 +141,7 @@
 	return ifat, nil
 }
 
-func newAddr(m *syscall.InterfaceAddrMessage) ([]Addr, os.Error) {
+func newAddr(m *syscall.InterfaceAddrMessage) ([]Addr, error) {
 	var ifat []Addr
 
 	sas, e := syscall.ParseRoutingSockaddr(m)

diff --git a/src/pkg/net/interface_darwin.go b/src/pkg/net/interface_darwin.go
index a7b68ad..1472afb 100644
--- a/src/pkg/net/interface_darwin.go
+++ b/src/pkg/net/interface_darwin.go

@@ -14,7 +14,7 @@
 // If the ifindex is zero, interfaceMulticastAddrTable returns
 // addresses for all network interfaces.  Otherwise it returns
 // addresses for a specific interface.
-func interfaceMulticastAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceMulticastAddrTable(ifindex int) ([]Addr, error) {
 	var (
 		tab   []byte
 		e     int
@@ -48,7 +48,7 @@
 	return ifmat, nil
 }
 
-func newMulticastAddr(m *syscall.InterfaceMulticastAddrMessage) ([]Addr, os.Error) {
+func newMulticastAddr(m *syscall.InterfaceMulticastAddrMessage) ([]Addr, error) {
 	var ifmat []Addr
 
 	sas, e := syscall.ParseRoutingSockaddr(m)

diff --git a/src/pkg/net/interface_freebsd.go b/src/pkg/net/interface_freebsd.go
index 20f506b..b0274f6 100644
--- a/src/pkg/net/interface_freebsd.go
+++ b/src/pkg/net/interface_freebsd.go

@@ -14,7 +14,7 @@
 // If the ifindex is zero, interfaceMulticastAddrTable returns
 // addresses for all network interfaces.  Otherwise it returns
 // addresses for a specific interface.
-func interfaceMulticastAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceMulticastAddrTable(ifindex int) ([]Addr, error) {
 	var (
 		tab   []byte
 		e     int
@@ -48,7 +48,7 @@
 	return ifmat, nil
 }
 
-func newMulticastAddr(m *syscall.InterfaceMulticastAddrMessage) ([]Addr, os.Error) {
+func newMulticastAddr(m *syscall.InterfaceMulticastAddrMessage) ([]Addr, error) {
 	var ifmat []Addr
 
 	sas, e := syscall.ParseRoutingSockaddr(m)

diff --git a/src/pkg/net/interface_linux.go b/src/pkg/net/interface_linux.go
index 36ae04f..cd0339d 100644
--- a/src/pkg/net/interface_linux.go
+++ b/src/pkg/net/interface_linux.go

@@ -16,7 +16,7 @@
 // If the ifindex is zero, interfaceTable returns mappings of all
 // network interfaces.  Otheriwse it returns a mapping of a specific
 // interface.
-func interfaceTable(ifindex int) ([]Interface, os.Error) {
+func interfaceTable(ifindex int) ([]Interface, error) {
 	var (
 		ift  []Interface
 		tab  []byte
@@ -101,11 +101,11 @@
 // If the ifindex is zero, interfaceAddrTable returns addresses
 // for all network interfaces.  Otherwise it returns addresses
 // for a specific interface.
-func interfaceAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceAddrTable(ifindex int) ([]Addr, error) {
 	var (
 		tab  []byte
 		e    int
-		err  os.Error
+		err  error
 		ifat []Addr
 		msgs []syscall.NetlinkMessage
 	)
@@ -128,7 +128,7 @@
 	return ifat, nil
 }
 
-func addrTable(msgs []syscall.NetlinkMessage, ifindex int) ([]Addr, os.Error) {
+func addrTable(msgs []syscall.NetlinkMessage, ifindex int) ([]Addr, error) {
 	var ifat []Addr
 
 	for _, m := range msgs {
@@ -175,10 +175,10 @@
 // If the ifindex is zero, interfaceMulticastAddrTable returns
 // addresses for all network interfaces.  Otherwise it returns
 // addresses for a specific interface.
-func interfaceMulticastAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceMulticastAddrTable(ifindex int) ([]Addr, error) {
 	var (
 		ifi *Interface
-		err os.Error
+		err error
 	)
 
 	if ifindex > 0 {

diff --git a/src/pkg/net/interface_openbsd.go b/src/pkg/net/interface_openbsd.go
index f181493..d8adb46 100644
--- a/src/pkg/net/interface_openbsd.go
+++ b/src/pkg/net/interface_openbsd.go

@@ -6,11 +6,9 @@
 
 package net
 
-import "os"
-
 // If the ifindex is zero, interfaceMulticastAddrTable returns
 // addresses for all network interfaces.  Otherwise it returns
 // addresses for a specific interface.
-func interfaceMulticastAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceMulticastAddrTable(ifindex int) ([]Addr, error) {
 	return nil, nil
 }

diff --git a/src/pkg/net/interface_stub.go b/src/pkg/net/interface_stub.go
index 282b38b..4876b3a 100644
--- a/src/pkg/net/interface_stub.go
+++ b/src/pkg/net/interface_stub.go

@@ -8,25 +8,23 @@
 
 package net
 
-import "os"
-
 // If the ifindex is zero, interfaceTable returns mappings of all
 // network interfaces.  Otheriwse it returns a mapping of a specific
 // interface.
-func interfaceTable(ifindex int) ([]Interface, os.Error) {
+func interfaceTable(ifindex int) ([]Interface, error) {
 	return nil, nil
 }
 
 // If the ifindex is zero, interfaceAddrTable returns addresses
 // for all network interfaces.  Otherwise it returns addresses
 // for a specific interface.
-func interfaceAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceAddrTable(ifindex int) ([]Addr, error) {
 	return nil, nil
 }
 
 // If the ifindex is zero, interfaceMulticastAddrTable returns
 // addresses for all network interfaces.  Otherwise it returns
 // addresses for a specific interface.
-func interfaceMulticastAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceMulticastAddrTable(ifindex int) ([]Addr, error) {
 	return nil, nil
 }

diff --git a/src/pkg/net/interface_test.go b/src/pkg/net/interface_test.go
index c918f24..cc61491 100644
--- a/src/pkg/net/interface_test.go
+++ b/src/pkg/net/interface_test.go

@@ -6,7 +6,6 @@
 
 import (
 	"bytes"
-	"os"
 	"reflect"
 	"strings"
 	"testing"
@@ -101,11 +100,11 @@
 	{"0123.4567.89AB.CDEF", HardwareAddr{1, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef}, ""},
 }
 
-func match(err os.Error, s string) bool {
+func match(err error, s string) bool {
 	if s == "" {
 		return err == nil
 	}
-	return err != nil && strings.Contains(err.String(), s)
+	return err != nil && strings.Contains(err.Error(), s)
 }
 
 func TestParseMAC(t *testing.T) {

diff --git a/src/pkg/net/interface_windows.go b/src/pkg/net/interface_windows.go
index 7f5169c..a1c8d95 100644
--- a/src/pkg/net/interface_windows.go
+++ b/src/pkg/net/interface_windows.go

@@ -21,7 +21,7 @@
 	return string(a[:i])
 }
 
-func getAdapterList() (*syscall.IpAdapterInfo, os.Error) {
+func getAdapterList() (*syscall.IpAdapterInfo, error) {
 	b := make([]byte, 1000)
 	l := uint32(len(b))
 	a := (*syscall.IpAdapterInfo)(unsafe.Pointer(&b[0]))
@@ -37,7 +37,7 @@
 	return a, nil
 }
 
-func getInterfaceList() ([]syscall.InterfaceInfo, os.Error) {
+func getInterfaceList() ([]syscall.InterfaceInfo, error) {
 	s, e := syscall.Socket(syscall.AF_INET, syscall.SOCK_DGRAM, syscall.IPPROTO_UDP)
 	if e != 0 {
 		return nil, os.NewSyscallError("Socket", e)
@@ -58,7 +58,7 @@
 // If the ifindex is zero, interfaceTable returns mappings of all
 // network interfaces.  Otheriwse it returns a mapping of a specific
 // interface.
-func interfaceTable(ifindex int) ([]Interface, os.Error) {
+func interfaceTable(ifindex int) ([]Interface, error) {
 	ai, e := getAdapterList()
 	if e != nil {
 		return nil, e
@@ -129,7 +129,7 @@
 // If the ifindex is zero, interfaceAddrTable returns addresses
 // for all network interfaces.  Otherwise it returns addresses
 // for a specific interface.
-func interfaceAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceAddrTable(ifindex int) ([]Addr, error) {
 	ai, e := getAdapterList()
 	if e != nil {
 		return nil, e
@@ -153,6 +153,6 @@
 // If the ifindex is zero, interfaceMulticastAddrTable returns
 // addresses for all network interfaces.  Otherwise it returns
 // addresses for a specific interface.
-func interfaceMulticastAddrTable(ifindex int) ([]Addr, os.Error) {
+func interfaceMulticastAddrTable(ifindex int) ([]Addr, error) {
 	return nil, nil
 }

diff --git a/src/pkg/net/ip.go b/src/pkg/net/ip.go
index 61dc3be..4a38882 100644
--- a/src/pkg/net/ip.go
+++ b/src/pkg/net/ip.go

@@ -12,8 +12,6 @@
 
 package net
 
-import "os"
-
 // IP address lengths (bytes).
 const (
 	IPv4len = 4
@@ -594,7 +592,7 @@
 	Text string
 }
 
-func (e *ParseError) String() string {
+func (e *ParseError) Error() string {
 	return "invalid " + e.Type + ": " + e.Text
 }
 
@@ -627,7 +625,7 @@
 // It returns the IP address and the network implied by the IP
 // and mask.  For example, ParseCIDR("192.168.100.1/16") returns
 // the IP address 192.168.100.1 and the network 192.168.0.0/16.
-func ParseCIDR(s string) (IP, *IPNet, os.Error) {
+func ParseCIDR(s string) (IP, *IPNet, error) {
 	i := byteIndex(s, '/')
 	if i < 0 {
 		return nil, nil, &ParseError{"CIDR address", s}

diff --git a/src/pkg/net/ip_test.go b/src/pkg/net/ip_test.go
index 07e627a..0ca315e 100644
--- a/src/pkg/net/ip_test.go
+++ b/src/pkg/net/ip_test.go

@@ -8,7 +8,6 @@
 	"bytes"
 	"reflect"
 	"testing"
-	"os"
 	"runtime"
 )
 
@@ -113,7 +112,7 @@
 	in  string
 	ip  IP
 	net *IPNet
-	err os.Error
+	err error
 }{
 	{"135.104.0.0/32", IPv4(135, 104, 0, 0), &IPNet{IPv4(135, 104, 0, 0), IPv4Mask(255, 255, 255, 255)}, nil},
 	{"0.0.0.0/24", IPv4(0, 0, 0, 0), &IPNet{IPv4(0, 0, 0, 0), IPv4Mask(255, 255, 255, 0)}, nil},

diff --git a/src/pkg/net/ipraw_test.go b/src/pkg/net/ipraw_test.go
index 6894ce6..60c405a 100644
--- a/src/pkg/net/ipraw_test.go
+++ b/src/pkg/net/ipraw_test.go

@@ -71,7 +71,7 @@
 
 	var (
 		laddr *IPAddr
-		err   os.Error
+		err   error
 	)
 	if *srchost != "" {
 		laddr, err = ResolveIPAddr("ip4", *srchost)

diff --git a/src/pkg/net/iprawsock.go b/src/pkg/net/iprawsock.go
index 662b9f5..b23213e 100644
--- a/src/pkg/net/iprawsock.go
+++ b/src/pkg/net/iprawsock.go

@@ -6,10 +6,6 @@
 
 package net
 
-import (
-	"os"
-)
-
 // IPAddr represents the address of a IP end point.
 type IPAddr struct {
 	IP IP
@@ -29,7 +25,7 @@
 // names to numeric addresses on the network net, which must be
 // "ip", "ip4" or "ip6".  A literal IPv6 host address must be
 // enclosed in square brackets, as in "[::]".
-func ResolveIPAddr(net, addr string) (*IPAddr, os.Error) {
+func ResolveIPAddr(net, addr string) (*IPAddr, error) {
 	ip, err := hostToIP(net, addr)
 	if err != nil {
 		return nil, err
@@ -38,7 +34,7 @@
 }
 
 // Convert "host" into IP address.
-func hostToIP(net, host string) (ip IP, err os.Error) {
+func hostToIP(net, host string) (ip IP, err error) {
 	var addr IP
 	// Try as an IP address.
 	addr = ParseIP(host)

diff --git a/src/pkg/net/iprawsock_plan9.go b/src/pkg/net/iprawsock_plan9.go
index 808e179..7e4bc56 100644
--- a/src/pkg/net/iprawsock_plan9.go
+++ b/src/pkg/net/iprawsock_plan9.go

@@ -17,17 +17,17 @@
 // Implementation of the Conn interface - see Conn for documentation.
 
 // Read implements the net.Conn Read method.
-func (c *IPConn) Read(b []byte) (n int, err os.Error) {
+func (c *IPConn) Read(b []byte) (n int, err error) {
 	return 0, os.EPLAN9
 }
 
 // Write implements the net.Conn Write method.
-func (c *IPConn) Write(b []byte) (n int, err os.Error) {
+func (c *IPConn) Write(b []byte) (n int, err error) {
 	return 0, os.EPLAN9
 }
 
 // Close closes the IP connection.
-func (c *IPConn) Close() os.Error {
+func (c *IPConn) Close() error {
 	return os.EPLAN9
 }
 
@@ -42,24 +42,24 @@
 }
 
 // SetTimeout implements the net.Conn SetTimeout method.
-func (c *IPConn) SetTimeout(nsec int64) os.Error {
+func (c *IPConn) SetTimeout(nsec int64) error {
 	return os.EPLAN9
 }
 
 // SetReadTimeout implements the net.Conn SetReadTimeout method.
-func (c *IPConn) SetReadTimeout(nsec int64) os.Error {
+func (c *IPConn) SetReadTimeout(nsec int64) error {
 	return os.EPLAN9
 }
 
 // SetWriteTimeout implements the net.Conn SetWriteTimeout method.
-func (c *IPConn) SetWriteTimeout(nsec int64) os.Error {
+func (c *IPConn) SetWriteTimeout(nsec int64) error {
 	return os.EPLAN9
 }
 
 // IP-specific methods.
 
 // ReadFrom implements the net.PacketConn ReadFrom method.
-func (c *IPConn) ReadFrom(b []byte) (n int, addr Addr, err os.Error) {
+func (c *IPConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
 	err = os.EPLAN9
 	return
 }
@@ -70,23 +70,23 @@
 // an error with Timeout() == true after a fixed time limit;
 // see SetTimeout and SetWriteTimeout.
 // On packet-oriented connections, write timeouts are rare.
-func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (n int, err os.Error) {
+func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (n int, err error) {
 	return 0, os.EPLAN9
 }
 
 // WriteTo implements the net.PacketConn WriteTo method.
-func (c *IPConn) WriteTo(b []byte, addr Addr) (n int, err os.Error) {
+func (c *IPConn) WriteTo(b []byte, addr Addr) (n int, err error) {
 	return 0, os.EPLAN9
 }
 
-func splitNetProto(netProto string) (net string, proto int, err os.Error) {
+func splitNetProto(netProto string) (net string, proto int, err error) {
 	err = os.EPLAN9
 	return
 }
 
 // DialIP connects to the remote address raddr on the network net,
 // which must be "ip", "ip4", or "ip6".
-func DialIP(netProto string, laddr, raddr *IPAddr) (c *IPConn, err os.Error) {
+func DialIP(netProto string, laddr, raddr *IPAddr) (c *IPConn, err error) {
 	return nil, os.EPLAN9
 }
 
@@ -94,6 +94,6 @@
 // local address laddr.  The returned connection c's ReadFrom
 // and WriteTo methods can be used to receive and send IP
 // packets with per-packet addressing.
-func ListenIP(netProto string, laddr *IPAddr) (c *IPConn, err os.Error) {
+func ListenIP(netProto string, laddr *IPAddr) (c *IPConn, err error) {
 	return nil, os.EPLAN9
 }

diff --git a/src/pkg/net/iprawsock_posix.go b/src/pkg/net/iprawsock_posix.go
index dafbdab..3bb99f9 100644
--- a/src/pkg/net/iprawsock_posix.go
+++ b/src/pkg/net/iprawsock_posix.go

@@ -9,6 +9,7 @@
 package net
 
 import (
+	"errors"
 	"os"
 	"syscall"
 )
@@ -33,7 +34,7 @@
 	return syscall.AF_INET6
 }
 
-func (a *IPAddr) sockaddr(family int) (syscall.Sockaddr, os.Error) {
+func (a *IPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
 	return ipToSockaddr(family, a.IP, 0)
 }
 
@@ -57,13 +58,13 @@
 // Implementation of the Conn interface - see Conn for documentation.
 
 // Read implements the net.Conn Read method.
-func (c *IPConn) Read(b []byte) (n int, err os.Error) {
+func (c *IPConn) Read(b []byte) (n int, err error) {
 	n, _, err = c.ReadFrom(b)
 	return
 }
 
 // Write implements the net.Conn Write method.
-func (c *IPConn) Write(b []byte) (n int, err os.Error) {
+func (c *IPConn) Write(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -71,7 +72,7 @@
 }
 
 // Close closes the IP connection.
-func (c *IPConn) Close() os.Error {
+func (c *IPConn) Close() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -97,7 +98,7 @@
 }
 
 // SetTimeout implements the net.Conn SetTimeout method.
-func (c *IPConn) SetTimeout(nsec int64) os.Error {
+func (c *IPConn) SetTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -105,7 +106,7 @@
 }
 
 // SetReadTimeout implements the net.Conn SetReadTimeout method.
-func (c *IPConn) SetReadTimeout(nsec int64) os.Error {
+func (c *IPConn) SetReadTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -113,7 +114,7 @@
 }
 
 // SetWriteTimeout implements the net.Conn SetWriteTimeout method.
-func (c *IPConn) SetWriteTimeout(nsec int64) os.Error {
+func (c *IPConn) SetWriteTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -122,7 +123,7 @@
 
 // SetReadBuffer sets the size of the operating system's
 // receive buffer associated with the connection.
-func (c *IPConn) SetReadBuffer(bytes int) os.Error {
+func (c *IPConn) SetReadBuffer(bytes int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -131,7 +132,7 @@
 
 // SetWriteBuffer sets the size of the operating system's
 // transmit buffer associated with the connection.
-func (c *IPConn) SetWriteBuffer(bytes int) os.Error {
+func (c *IPConn) SetWriteBuffer(bytes int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -147,7 +148,7 @@
 // ReadFromIP can be made to time out and return an error with
 // Timeout() == true after a fixed time limit; see SetTimeout and
 // SetReadTimeout.
-func (c *IPConn) ReadFromIP(b []byte) (n int, addr *IPAddr, err os.Error) {
+func (c *IPConn) ReadFromIP(b []byte) (n int, addr *IPAddr, err error) {
 	if !c.ok() {
 		return 0, nil, os.EINVAL
 	}
@@ -169,7 +170,7 @@
 }
 
 // ReadFrom implements the net.PacketConn ReadFrom method.
-func (c *IPConn) ReadFrom(b []byte) (n int, addr Addr, err os.Error) {
+func (c *IPConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
 	if !c.ok() {
 		return 0, nil, os.EINVAL
 	}
@@ -183,19 +184,19 @@
 // an error with Timeout() == true after a fixed time limit;
 // see SetTimeout and SetWriteTimeout.
 // On packet-oriented connections, write timeouts are rare.
-func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (n int, err os.Error) {
+func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
 	sa, err1 := addr.sockaddr(c.fd.family)
 	if err1 != nil {
-		return 0, &OpError{Op: "write", Net: "ip", Addr: addr, Error: err1}
+		return 0, &OpError{Op: "write", Net: "ip", Addr: addr, Err: err1}
 	}
 	return c.fd.WriteTo(b, sa)
 }
 
 // WriteTo implements the net.PacketConn WriteTo method.
-func (c *IPConn) WriteTo(b []byte, addr Addr) (n int, err os.Error) {
+func (c *IPConn) WriteTo(b []byte, addr Addr) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -206,10 +207,10 @@
 	return c.WriteToIP(b, a)
 }
 
-func splitNetProto(netProto string) (net string, proto int, err os.Error) {
+func splitNetProto(netProto string) (net string, proto int, err error) {
 	i := last(netProto, ':')
 	if i < 0 { // no colon
-		return "", 0, os.NewError("no IP protocol specified")
+		return "", 0, errors.New("no IP protocol specified")
 	}
 	net = netProto[0:i]
 	protostr := netProto[i+1:]
@@ -225,7 +226,7 @@
 
 // DialIP connects to the remote address raddr on the network net,
 // which must be "ip", "ip4", or "ip6".
-func DialIP(netProto string, laddr, raddr *IPAddr) (c *IPConn, err os.Error) {
+func DialIP(netProto string, laddr, raddr *IPAddr) (c *IPConn, err error) {
 	net, proto, err := splitNetProto(netProto)
 	if err != nil {
 		return
@@ -249,7 +250,7 @@
 // local address laddr.  The returned connection c's ReadFrom
 // and WriteTo methods can be used to receive and send IP
 // packets with per-packet addressing.
-func ListenIP(netProto string, laddr *IPAddr) (c *IPConn, err os.Error) {
+func ListenIP(netProto string, laddr *IPAddr) (c *IPConn, err error) {
 	net, proto, err := splitNetProto(netProto)
 	if err != nil {
 		return
@@ -267,7 +268,7 @@
 }
 
 // BindToDevice binds an IPConn to a network interface.
-func (c *IPConn) BindToDevice(device string) os.Error {
+func (c *IPConn) BindToDevice(device string) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -279,4 +280,4 @@
 // File returns a copy of the underlying os.File, set to blocking mode.
 // It is the caller's responsibility to close f when finished.
 // Closing c does not affect f, and closing f does not affect c.
-func (c *IPConn) File() (f *os.File, err os.Error) { return c.fd.dup() }
+func (c *IPConn) File() (f *os.File, err error) { return c.fd.dup() }

diff --git a/src/pkg/net/ipsock.go b/src/pkg/net/ipsock.go
index 4e2a562..716454d 100644
--- a/src/pkg/net/ipsock.go
+++ b/src/pkg/net/ipsock.go

@@ -6,10 +6,6 @@
 
 package net
 
-import (
-	"os"
-)
-
 var supportsIPv6, supportsIPv4map = probeIPv6Stack()
 
 func firstFavoriteAddr(filter func(IP) IP, addrs []string) (addr IP) {
@@ -61,14 +57,14 @@
 
 type InvalidAddrError string
 
-func (e InvalidAddrError) String() string  { return string(e) }
+func (e InvalidAddrError) Error() string   { return string(e) }
 func (e InvalidAddrError) Timeout() bool   { return false }
 func (e InvalidAddrError) Temporary() bool { return false }
 
 // SplitHostPort splits a network address of the form
 // "host:port" or "[host]:port" into host and port.
 // The latter form must be used when host contains a colon.
-func SplitHostPort(hostport string) (host, port string, err os.Error) {
+func SplitHostPort(hostport string) (host, port string, err error) {
 	// The port starts after the last colon.
 	i := last(hostport, ':')
 	if i < 0 {
@@ -102,7 +98,7 @@
 }
 
 // Convert "host:port" into IP address and port.
-func hostPortToIP(net, hostport string) (ip IP, iport int, err os.Error) {
+func hostPortToIP(net, hostport string) (ip IP, iport int, err error) {
 	var (
 		addr IP
 		p, i int

diff --git a/src/pkg/net/ipsock_plan9.go b/src/pkg/net/ipsock_plan9.go
index 9e5da6d..42fb408 100644
--- a/src/pkg/net/ipsock_plan9.go
+++ b/src/pkg/net/ipsock_plan9.go

@@ -7,6 +7,8 @@
 package net
 
 import (
+	"errors"
+	"io"
 	"os"
 )
 
@@ -18,7 +20,7 @@
 }
 
 // parsePlan9Addr parses address of the form [ip!]port (e.g. 127.0.0.1!80).
-func parsePlan9Addr(s string) (ip IP, iport int, err os.Error) {
+func parsePlan9Addr(s string) (ip IP, iport int, err error) {
 	var (
 		addr IP
 		p, i int
@@ -29,13 +31,13 @@
 	if i >= 0 {
 		addr = ParseIP(s[:i])
 		if addr == nil {
-			err = os.NewError("net: parsing IP failed")
+			err = errors.New("net: parsing IP failed")
 			goto Error
 		}
 	}
 	p, _, ok = dtoi(s[i+1:], 0)
 	if !ok {
-		err = os.NewError("net: parsing port failed")
+		err = errors.New("net: parsing port failed")
 		goto Error
 	}
 	if p < 0 || p > 0xFFFF {
@@ -48,7 +50,7 @@
 	return nil, 0, err
 }
 
-func readPlan9Addr(proto, filename string) (addr Addr, err os.Error) {
+func readPlan9Addr(proto, filename string) (addr Addr, err error) {
 	var buf [128]byte
 
 	f, err := os.Open(filename)
@@ -69,7 +71,7 @@
 	case "udp":
 		addr = &UDPAddr{ip, port}
 	default:
-		return nil, os.NewError("unknown protocol " + proto)
+		return nil, errors.New("unknown protocol " + proto)
 	}
 	return addr, nil
 }
@@ -89,7 +91,7 @@
 // Implementation of the Conn interface - see Conn for documentation.
 
 // Read implements the net.Conn Read method.
-func (c *plan9Conn) Read(b []byte) (n int, err os.Error) {
+func (c *plan9Conn) Read(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -100,7 +102,7 @@
 		}
 	}
 	n, err = c.data.Read(b)
-	if c.proto == "udp" && err == os.EOF {
+	if c.proto == "udp" && err == io.EOF {
 		n = 0
 		err = nil
 	}
@@ -108,7 +110,7 @@
 }
 
 // Write implements the net.Conn Write method.
-func (c *plan9Conn) Write(b []byte) (n int, err os.Error) {
+func (c *plan9Conn) Write(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -122,7 +124,7 @@
 }
 
 // Close closes the connection.
-func (c *plan9Conn) Close() os.Error {
+func (c *plan9Conn) Close() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -155,7 +157,7 @@
 }
 
 // SetTimeout implements the net.Conn SetTimeout method.
-func (c *plan9Conn) SetTimeout(nsec int64) os.Error {
+func (c *plan9Conn) SetTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -163,7 +165,7 @@
 }
 
 // SetReadTimeout implements the net.Conn SetReadTimeout method.
-func (c *plan9Conn) SetReadTimeout(nsec int64) os.Error {
+func (c *plan9Conn) SetReadTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -171,14 +173,14 @@
 }
 
 // SetWriteTimeout implements the net.Conn SetWriteTimeout method.
-func (c *plan9Conn) SetWriteTimeout(nsec int64) os.Error {
+func (c *plan9Conn) SetWriteTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
 	return os.EPLAN9
 }
 
-func startPlan9(net string, addr Addr) (ctl *os.File, dest, proto, name string, err os.Error) {
+func startPlan9(net string, addr Addr) (ctl *os.File, dest, proto, name string, err error) {
 	var (
 		ip   IP
 		port int
@@ -213,7 +215,7 @@
 	return f, dest, proto, string(buf[:n]), nil
 }
 
-func dialPlan9(net string, laddr, raddr Addr) (c *plan9Conn, err os.Error) {
+func dialPlan9(net string, laddr, raddr Addr) (c *plan9Conn, err error) {
 	f, dest, proto, name, err := startPlan9(net, raddr)
 	if err != nil {
 		return
@@ -239,7 +241,7 @@
 	laddr            Addr
 }
 
-func listenPlan9(net string, laddr Addr) (l *plan9Listener, err os.Error) {
+func listenPlan9(net string, laddr Addr) (l *plan9Listener, err error) {
 	f, dest, proto, name, err := startPlan9(net, laddr)
 	if err != nil {
 		return
@@ -265,7 +267,7 @@
 	return newPlan9Conn(l.proto, l.name, l.ctl, l.laddr, nil)
 }
 
-func (l *plan9Listener) acceptPlan9() (c *plan9Conn, err os.Error) {
+func (l *plan9Listener) acceptPlan9() (c *plan9Conn, err error) {
 	f, err := os.Open(l.dir + "/listen")
 	if err != nil {
 		return
@@ -287,7 +289,7 @@
 	return newPlan9Conn(l.proto, name, f, laddr, raddr), nil
 }
 
-func (l *plan9Listener) Accept() (c Conn, err os.Error) {
+func (l *plan9Listener) Accept() (c Conn, err error) {
 	c1, err := l.acceptPlan9()
 	if err != nil {
 		return
@@ -295,7 +297,7 @@
 	return c1, nil
 }
 
-func (l *plan9Listener) Close() os.Error {
+func (l *plan9Listener) Close() error {
 	if l == nil || l.ctl == nil {
 		return os.EINVAL
 	}

diff --git a/src/pkg/net/ipsock_posix.go b/src/pkg/net/ipsock_posix.go
index 049df9e..d5b8f21 100644
--- a/src/pkg/net/ipsock_posix.go
+++ b/src/pkg/net/ipsock_posix.go

@@ -6,10 +6,7 @@
 
 package net
 
-import (
-	"os"
-	"syscall"
-)
+import "syscall"
 
 // Should we try to use the IPv4 socket interface if we're
 // only dealing with IPv4 sockets?  As long as the host system
@@ -105,12 +102,12 @@
 // be converted into a syscall.Sockaddr.
 type sockaddr interface {
 	Addr
-	sockaddr(family int) (syscall.Sockaddr, os.Error)
+	sockaddr(family int) (syscall.Sockaddr, error)
 	family() int
 }
 
-func internetSocket(net string, laddr, raddr sockaddr, socktype, proto int, mode string, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err os.Error) {
-	var oserr os.Error
+func internetSocket(net string, laddr, raddr sockaddr, socktype, proto int, mode string, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err error) {
+	var oserr error
 	var la, ra syscall.Sockaddr
 	family := favoriteAddrFamily(net, raddr, laddr, mode)
 	if laddr != nil {
@@ -137,7 +134,7 @@
 	return nil, &OpError{mode, net, addr, oserr}
 }
 
-func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, os.Error) {
+func ipToSockaddr(family int, ip IP, port int) (syscall.Sockaddr, error) {
 	switch family {
 	case syscall.AF_INET:
 		if len(ip) == 0 {

diff --git a/src/pkg/net/lookup_plan9.go b/src/pkg/net/lookup_plan9.go
index a14c592..027794a 100644
--- a/src/pkg/net/lookup_plan9.go
+++ b/src/pkg/net/lookup_plan9.go

@@ -5,10 +5,11 @@
 package net
 
 import (
+	"errors"
 	"os"
 )
 
-func query(filename, query string, bufSize int) (res []string, err os.Error) {
+func query(filename, query string, bufSize int) (res []string, err error) {
 	file, err := os.OpenFile(filename, os.O_RDWR, 0)
 	if err != nil {
 		return
@@ -34,7 +35,7 @@
 	return
 }
 
-func queryCS(net, host, service string) (res []string, err os.Error) {
+func queryCS(net, host, service string) (res []string, err error) {
 	switch net {
 	case "tcp4", "tcp6":
 		net = "tcp"
@@ -47,7 +48,7 @@
 	return query("/net/cs", net+"!"+host+"!"+service, 128)
 }
 
-func queryCS1(net string, ip IP, port int) (clone, dest string, err os.Error) {
+func queryCS1(net string, ip IP, port int) (clone, dest string, err error) {
 	ips := "*"
 	if len(ip) != 0 && !ip.IsUnspecified() {
 		ips = ip.String()
@@ -58,19 +59,19 @@
 	}
 	f := getFields(lines[0])
 	if len(f) < 2 {
-		return "", "", os.NewError("net: bad response from ndb/cs")
+		return "", "", errors.New("net: bad response from ndb/cs")
 	}
 	clone, dest = f[0], f[1]
 	return
 }
 
-func queryDNS(addr string, typ string) (res []string, err os.Error) {
+func queryDNS(addr string, typ string) (res []string, err error) {
 	return query("/net/dns", addr+" "+typ, 1024)
 }
 
 // LookupHost looks up the given host using the local resolver.
 // It returns an array of that host's addresses.
-func LookupHost(host string) (addrs []string, err os.Error) {
+func LookupHost(host string) (addrs []string, err error) {
 	// Use /net/cs insead of /net/dns because cs knows about
 	// host names in local network (e.g. from /lib/ndb/local)
 	lines, err := queryCS("tcp", host, "1")
@@ -96,7 +97,7 @@
 
 // LookupIP looks up host using the local resolver.
 // It returns an array of that host's IPv4 and IPv6 addresses.
-func LookupIP(host string) (ips []IP, err os.Error) {
+func LookupIP(host string) (ips []IP, err error) {
 	addrs, err := LookupHost(host)
 	if err != nil {
 		return
@@ -110,7 +111,7 @@
 }
 
 // LookupPort looks up the port for the given network and service.
-func LookupPort(network, service string) (port int, err os.Error) {
+func LookupPort(network, service string) (port int, err error) {
 	switch network {
 	case "tcp4", "tcp6":
 		network = "tcp"
@@ -143,7 +144,7 @@
 // Callers that do not care about the canonical name can call
 // LookupHost or LookupIP directly; both take care of resolving
 // the canonical name as part of the lookup.
-func LookupCNAME(name string) (cname string, err os.Error) {
+func LookupCNAME(name string) (cname string, err error) {
 	lines, err := queryDNS(name, "cname")
 	if err != nil {
 		return
@@ -153,7 +154,7 @@
 			return f[2] + ".", nil
 		}
 	}
-	return "", os.NewError("net: bad response from ndb/dns")
+	return "", errors.New("net: bad response from ndb/dns")
 }
 
 // LookupSRV tries to resolve an SRV query of the given service,
@@ -165,7 +166,7 @@
 // That is, it looks up _service._proto.name.  To accommodate services
 // publishing SRV records under non-standard names, if both service
 // and proto are empty strings, LookupSRV looks up name directly.
-func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err os.Error) {
+func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
 	var target string
 	if service == "" && proto == "" {
 		target = name
@@ -195,7 +196,7 @@
 }
 
 // LookupMX returns the DNS MX records for the given domain name sorted by preference.
-func LookupMX(name string) (mx []*MX, err os.Error) {
+func LookupMX(name string) (mx []*MX, err error) {
 	lines, err := queryDNS(name, "mx")
 	if err != nil {
 		return
@@ -214,7 +215,7 @@
 }
 
 // LookupTXT returns the DNS TXT records for the given domain name.
-func LookupTXT(name string) (txt []string, err os.Error) {
+func LookupTXT(name string) (txt []string, err error) {
 	lines, err := queryDNS(name, "txt")
 	if err != nil {
 		return
@@ -229,7 +230,7 @@
 
 // LookupAddr performs a reverse lookup for the given address, returning a list
 // of names mapping to that address.
-func LookupAddr(addr string) (name []string, err os.Error) {
+func LookupAddr(addr string) (name []string, err error) {
 	arpa, err := reverseaddr(addr)
 	if err != nil {
 		return

diff --git a/src/pkg/net/lookup_unix.go b/src/pkg/net/lookup_unix.go
index 6e79295..aae6d6c 100644
--- a/src/pkg/net/lookup_unix.go
+++ b/src/pkg/net/lookup_unix.go

@@ -7,7 +7,7 @@
 package net
 
 import (
-	"os"
+	"errors"
 	"sync"
 )
 
@@ -43,18 +43,18 @@
 
 // lookupProtocol looks up IP protocol name in /etc/protocols and
 // returns correspondent protocol number.
-func lookupProtocol(name string) (proto int, err os.Error) {
+func lookupProtocol(name string) (proto int, err error) {
 	onceReadProtocols.Do(readProtocols)
 	proto, found := protocols[name]
 	if !found {
-		return 0, os.NewError("unknown IP protocol specified: " + name)
+		return 0, errors.New("unknown IP protocol specified: " + name)
 	}
 	return
 }
 
 // LookupHost looks up the given host using the local resolver.
 // It returns an array of that host's addresses.
-func LookupHost(host string) (addrs []string, err os.Error) {
+func LookupHost(host string) (addrs []string, err error) {
 	addrs, err, ok := cgoLookupHost(host)
 	if !ok {
 		addrs, err = goLookupHost(host)
@@ -64,7 +64,7 @@
 
 // LookupIP looks up host using the local resolver.
 // It returns an array of that host's IPv4 and IPv6 addresses.
-func LookupIP(host string) (addrs []IP, err os.Error) {
+func LookupIP(host string) (addrs []IP, err error) {
 	addrs, err, ok := cgoLookupIP(host)
 	if !ok {
 		addrs, err = goLookupIP(host)
@@ -73,7 +73,7 @@
 }
 
 // LookupPort looks up the port for the given network and service.
-func LookupPort(network, service string) (port int, err os.Error) {
+func LookupPort(network, service string) (port int, err error) {
 	port, err, ok := cgoLookupPort(network, service)
 	if !ok {
 		port, err = goLookupPort(network, service)
@@ -85,7 +85,7 @@
 // Callers that do not care about the canonical name can call
 // LookupHost or LookupIP directly; both take care of resolving
 // the canonical name as part of the lookup.
-func LookupCNAME(name string) (cname string, err os.Error) {
+func LookupCNAME(name string) (cname string, err error) {
 	cname, err, ok := cgoLookupCNAME(name)
 	if !ok {
 		cname, err = goLookupCNAME(name)
@@ -102,7 +102,7 @@
 // That is, it looks up _service._proto.name.  To accommodate services
 // publishing SRV records under non-standard names, if both service
 // and proto are empty strings, LookupSRV looks up name directly.
-func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err os.Error) {
+func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
 	var target string
 	if service == "" && proto == "" {
 		target = name
@@ -124,7 +124,7 @@
 }
 
 // LookupMX returns the DNS MX records for the given domain name sorted by preference.
-func LookupMX(name string) (mx []*MX, err os.Error) {
+func LookupMX(name string) (mx []*MX, err error) {
 	_, records, err := lookup(name, dnsTypeMX)
 	if err != nil {
 		return
@@ -139,7 +139,7 @@
 }
 
 // LookupTXT returns the DNS TXT records for the given domain name.
-func LookupTXT(name string) (txt []string, err os.Error) {
+func LookupTXT(name string) (txt []string, err error) {
 	_, records, err := lookup(name, dnsTypeTXT)
 	if err != nil {
 		return
@@ -153,7 +153,7 @@
 
 // LookupAddr performs a reverse lookup for the given address, returning a list
 // of names mapping to that address.
-func LookupAddr(addr string) (name []string, err os.Error) {
+func LookupAddr(addr string) (name []string, err error) {
 	name = lookupStaticAddr(addr)
 	if len(name) > 0 {
 		return

diff --git a/src/pkg/net/lookup_windows.go b/src/pkg/net/lookup_windows.go
index ea939f8..53cb8f4 100644
--- a/src/pkg/net/lookup_windows.go
+++ b/src/pkg/net/lookup_windows.go

@@ -5,6 +5,7 @@
 package net
 
 import (
+	"errors"
 	"syscall"
 	"unsafe"
 	"os"
@@ -18,7 +19,7 @@
 )
 
 // lookupProtocol looks up IP protocol name and returns correspondent protocol number.
-func lookupProtocol(name string) (proto int, err os.Error) {
+func lookupProtocol(name string) (proto int, err error) {
 	protoentLock.Lock()
 	defer protoentLock.Unlock()
 	p, e := syscall.GetProtoByName(name)
@@ -28,7 +29,7 @@
 	return int(p.Proto), nil
 }
 
-func LookupHost(name string) (addrs []string, err os.Error) {
+func LookupHost(name string) (addrs []string, err error) {
 	ips, err := LookupIP(name)
 	if err != nil {
 		return
@@ -40,7 +41,7 @@
 	return
 }
 
-func LookupIP(name string) (addrs []IP, err os.Error) {
+func LookupIP(name string) (addrs []IP, err error) {
 	hostentLock.Lock()
 	defer hostentLock.Unlock()
 	h, e := syscall.GetHostByName(name)
@@ -61,7 +62,7 @@
 	return addrs, nil
 }
 
-func LookupPort(network, service string) (port int, err os.Error) {
+func LookupPort(network, service string) (port int, err error) {
 	switch network {
 	case "tcp4", "tcp6":
 		network = "tcp"
@@ -77,7 +78,7 @@
 	return int(syscall.Ntohs(s.Port)), nil
 }
 
-func LookupCNAME(name string) (cname string, err os.Error) {
+func LookupCNAME(name string) (cname string, err error) {
 	var r *syscall.DNSRecord
 	e := syscall.DnsQuery(name, syscall.DNS_TYPE_CNAME, 0, nil, &r, nil)
 	if int(e) != 0 {
@@ -100,7 +101,7 @@
 // That is, it looks up _service._proto.name.  To accommodate services
 // publishing SRV records under non-standard names, if both service
 // and proto are empty strings, LookupSRV looks up name directly.
-func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err os.Error) {
+func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
 	var target string
 	if service == "" && proto == "" {
 		target = name
@@ -122,7 +123,7 @@
 	return name, addrs, nil
 }
 
-func LookupMX(name string) (mx []*MX, err os.Error) {
+func LookupMX(name string) (mx []*MX, err error) {
 	var r *syscall.DNSRecord
 	e := syscall.DnsQuery(name, syscall.DNS_TYPE_MX, 0, nil, &r, nil)
 	if int(e) != 0 {
@@ -138,11 +139,11 @@
 	return mx, nil
 }
 
-func LookupTXT(name string) (txt []string, err os.Error) {
-	return nil, os.NewError("net.LookupTXT is not implemented on Windows")
+func LookupTXT(name string) (txt []string, err error) {
+	return nil, errors.New("net.LookupTXT is not implemented on Windows")
 }
 
-func LookupAddr(addr string) (name []string, err os.Error) {
+func LookupAddr(addr string) (name []string, err error) {
 	arpa, err := reverseaddr(addr)
 	if err != nil {
 		return nil, err

diff --git a/src/pkg/net/net.go b/src/pkg/net/net.go
index 5c84d34..48f0ae7 100644
--- a/src/pkg/net/net.go
+++ b/src/pkg/net/net.go

@@ -9,7 +9,7 @@
 // TODO(rsc):
 //	support for raw ethernet sockets
 
-import "os"
+import "errors"
 
 // Addr represents a network end point address.
 type Addr interface {
@@ -22,15 +22,15 @@
 	// Read reads data from the connection.
 	// Read can be made to time out and return a net.Error with Timeout() == true
 	// after a fixed time limit; see SetTimeout and SetReadTimeout.
-	Read(b []byte) (n int, err os.Error)
+	Read(b []byte) (n int, err error)
 
 	// Write writes data to the connection.
 	// Write can be made to time out and return a net.Error with Timeout() == true
 	// after a fixed time limit; see SetTimeout and SetWriteTimeout.
-	Write(b []byte) (n int, err os.Error)
+	Write(b []byte) (n int, err error)
 
 	// Close closes the connection.
-	Close() os.Error
+	Close() error
 
 	// LocalAddr returns the local network address.
 	LocalAddr() Addr
@@ -40,24 +40,24 @@
 
 	// SetTimeout sets the read and write deadlines associated
 	// with the connection.
-	SetTimeout(nsec int64) os.Error
+	SetTimeout(nsec int64) error
 
 	// SetReadTimeout sets the time (in nanoseconds) that
 	// Read will wait for data before returning an error with Timeout() == true.
 	// Setting nsec == 0 (the default) disables the deadline.
-	SetReadTimeout(nsec int64) os.Error
+	SetReadTimeout(nsec int64) error
 
 	// SetWriteTimeout sets the time (in nanoseconds) that
 	// Write will wait to send its data before returning an error with Timeout() == true.
 	// Setting nsec == 0 (the default) disables the deadline.
 	// Even if write times out, it may return n > 0, indicating that
 	// some of the data was successfully written.
-	SetWriteTimeout(nsec int64) os.Error
+	SetWriteTimeout(nsec int64) error
 }
 
 // An Error represents a network error.
 type Error interface {
-	os.Error
+	error
 	Timeout() bool   // Is the error a timeout?
 	Temporary() bool // Is the error temporary?
 }
@@ -71,60 +71,60 @@
 	// ReadFrom can be made to time out and return
 	// an error with Timeout() == true after a fixed time limit;
 	// see SetTimeout and SetReadTimeout.
-	ReadFrom(b []byte) (n int, addr Addr, err os.Error)
+	ReadFrom(b []byte) (n int, addr Addr, err error)
 
 	// WriteTo writes a packet with payload b to addr.
 	// WriteTo can be made to time out and return
 	// an error with Timeout() == true after a fixed time limit;
 	// see SetTimeout and SetWriteTimeout.
 	// On packet-oriented connections, write timeouts are rare.
-	WriteTo(b []byte, addr Addr) (n int, err os.Error)
+	WriteTo(b []byte, addr Addr) (n int, err error)
 
 	// Close closes the connection.
-	Close() os.Error
+	Close() error
 
 	// LocalAddr returns the local network address.
 	LocalAddr() Addr
 
 	// SetTimeout sets the read and write deadlines associated
 	// with the connection.
-	SetTimeout(nsec int64) os.Error
+	SetTimeout(nsec int64) error
 
 	// SetReadTimeout sets the time (in nanoseconds) that
 	// Read will wait for data before returning an error with Timeout() == true.
 	// Setting nsec == 0 (the default) disables the deadline.
-	SetReadTimeout(nsec int64) os.Error
+	SetReadTimeout(nsec int64) error
 
 	// SetWriteTimeout sets the time (in nanoseconds) that
 	// Write will wait to send its data before returning an error with Timeout() == true.
 	// Setting nsec == 0 (the default) disables the deadline.
 	// Even if write times out, it may return n > 0, indicating that
 	// some of the data was successfully written.
-	SetWriteTimeout(nsec int64) os.Error
+	SetWriteTimeout(nsec int64) error
 }
 
 // A Listener is a generic network listener for stream-oriented protocols.
 type Listener interface {
 	// Accept waits for and returns the next connection to the listener.
-	Accept() (c Conn, err os.Error)
+	Accept() (c Conn, err error)
 
 	// Close closes the listener.
-	Close() os.Error
+	Close() error
 
 	// Addr returns the listener's network address.
 	Addr() Addr
 }
 
-var errMissingAddress = os.NewError("missing address")
+var errMissingAddress = errors.New("missing address")
 
 type OpError struct {
-	Op    string
-	Net   string
-	Addr  Addr
-	Error os.Error
+	Op   string
+	Net  string
+	Addr Addr
+	Err  error
 }
 
-func (e *OpError) String() string {
+func (e *OpError) Error() string {
 	if e == nil {
 		return "<nil>"
 	}
@@ -135,7 +135,7 @@
 	if e.Addr != nil {
 		s += " " + e.Addr.String()
 	}
-	s += ": " + e.Error.String()
+	s += ": " + e.Err.Error()
 	return s
 }
 
@@ -144,7 +144,7 @@
 }
 
 func (e *OpError) Temporary() bool {
-	t, ok := e.Error.(temporary)
+	t, ok := e.Err.(temporary)
 	return ok && t.Temporary()
 }
 
@@ -153,20 +153,20 @@
 }
 
 func (e *OpError) Timeout() bool {
-	t, ok := e.Error.(timeout)
+	t, ok := e.Err.(timeout)
 	return ok && t.Timeout()
 }
 
 type AddrError struct {
-	Error string
-	Addr  string
+	Err  string
+	Addr string
 }
 
-func (e *AddrError) String() string {
+func (e *AddrError) Error() string {
 	if e == nil {
 		return "<nil>"
 	}
-	s := e.Error
+	s := e.Err
 	if e.Addr != "" {
 		s += " " + e.Addr
 	}
@@ -183,6 +183,6 @@
 
 type UnknownNetworkError string
 
-func (e UnknownNetworkError) String() string  { return "unknown network " + string(e) }
+func (e UnknownNetworkError) Error() string   { return "unknown network " + string(e) }
 func (e UnknownNetworkError) Temporary() bool { return false }
 func (e UnknownNetworkError) Timeout() bool   { return false }

diff --git a/src/pkg/net/net_test.go b/src/pkg/net/net_test.go
index 94d620e..d2839d7 100644
--- a/src/pkg/net/net_test.go
+++ b/src/pkg/net/net_test.go

@@ -6,7 +6,7 @@
 
 import (
 	"flag"
-	"os"
+	"io"
 	"regexp"
 	"runtime"
 	"testing"
@@ -79,7 +79,7 @@
 			t.Errorf("#%d: nil error, want match for %#q", i, tt.Pattern)
 			continue
 		}
-		s := e.String()
+		s := e.Error()
 		match, _ := regexp.MatchString(tt.Pattern, s)
 		if !match {
 			t.Errorf("#%d: %q, want match for %#q", i, s, tt.Pattern)
@@ -119,8 +119,8 @@
 		if len(tt.ErrPrefix) == 0 && e != nil {
 			t.Errorf("#%d: expected <nil>, got %q (error)", i, e)
 		}
-		if e != nil && e.(*DNSError).Error != tt.ErrPrefix {
-			t.Errorf("#%d: expected %q, got %q (mismatched error)", i, tt.ErrPrefix, e.(*DNSError).Error)
+		if e != nil && e.(*DNSError).Err != tt.ErrPrefix {
+			t.Errorf("#%d: expected %q, got %q (mismatched error)", i, tt.ErrPrefix, e.(*DNSError).Err)
 		}
 		if a != tt.Reverse {
 			t.Errorf("#%d: expected %q, got %q (reverse address)", i, tt.Reverse, a)
@@ -146,7 +146,7 @@
 		}
 		var buf [10]byte
 		n, err := c.Read(buf[:])
-		if n != 0 || err != os.EOF {
+		if n != 0 || err != io.EOF {
 			t.Fatalf("server Read = %d, %v; want 0, os.EOF", n, err)
 		}
 		c.Write([]byte("response"))

diff --git a/src/pkg/net/newpollserver.go b/src/pkg/net/newpollserver.go
index 3c9a6da..9ad6f7b 100644
--- a/src/pkg/net/newpollserver.go
+++ b/src/pkg/net/newpollserver.go

@@ -11,7 +11,7 @@
 	"syscall"
 )
 
-func newPollServer() (s *pollServer, err os.Error) {
+func newPollServer() (s *pollServer, err error) {
 	s = new(pollServer)
 	s.cr = make(chan *netFD, 1)
 	s.cw = make(chan *netFD, 1)

diff --git a/src/pkg/net/parse.go b/src/pkg/net/parse.go
index 0d30a7a..4c4200a 100644
--- a/src/pkg/net/parse.go
+++ b/src/pkg/net/parse.go

@@ -54,7 +54,7 @@
 		if n >= 0 {
 			f.data = f.data[0 : ln+n]
 		}
-		if err == os.EOF {
+		if err == io.EOF {
 			f.atEOF = true
 		}
 	}
@@ -62,7 +62,7 @@
 	return
 }
 
-func open(name string) (*file, os.Error) {
+func open(name string) (*file, error) {
 	fd, err := os.Open(name)
 	if err != nil {
 		return nil, err

diff --git a/src/pkg/net/pipe.go b/src/pkg/net/pipe.go
index c0bbd35..b99e6e6 100644
--- a/src/pkg/net/pipe.go
+++ b/src/pkg/net/pipe.go

@@ -1,8 +1,8 @@
 package net
 
 import (
+	"errors"
 	"io"
-	"os"
 )
 
 // Pipe creates a synchronous, in-memory, full duplex
@@ -32,7 +32,7 @@
 	return "pipe"
 }
 
-func (p *pipe) Close() os.Error {
+func (p *pipe) Close() error {
 	err := p.PipeReader.Close()
 	err1 := p.PipeWriter.Close()
 	if err == nil {
@@ -49,14 +49,14 @@
 	return pipeAddr(0)
 }
 
-func (p *pipe) SetTimeout(nsec int64) os.Error {
-	return os.NewError("net.Pipe does not support timeouts")
+func (p *pipe) SetTimeout(nsec int64) error {
+	return errors.New("net.Pipe does not support timeouts")
 }
 
-func (p *pipe) SetReadTimeout(nsec int64) os.Error {
-	return os.NewError("net.Pipe does not support timeouts")
+func (p *pipe) SetReadTimeout(nsec int64) error {
+	return errors.New("net.Pipe does not support timeouts")
 }
 
-func (p *pipe) SetWriteTimeout(nsec int64) os.Error {
-	return os.NewError("net.Pipe does not support timeouts")
+func (p *pipe) SetWriteTimeout(nsec int64) error {
+	return errors.New("net.Pipe does not support timeouts")
 }

diff --git a/src/pkg/net/pipe_test.go b/src/pkg/net/pipe_test.go
index 7e4c6db..afe4f24 100644
--- a/src/pkg/net/pipe_test.go
+++ b/src/pkg/net/pipe_test.go

@@ -7,7 +7,6 @@
 import (
 	"bytes"
 	"io"
-	"os"
 	"testing"
 )
 
@@ -22,7 +21,7 @@
 	c <- 0
 }
 
-func checkRead(t *testing.T, r io.Reader, data []byte, wantErr os.Error) {
+func checkRead(t *testing.T, r io.Reader, data []byte, wantErr error) {
 	buf := make([]byte, len(data)+10)
 	n, err := r.Read(buf)
 	if err != wantErr {
@@ -52,6 +51,6 @@
 	checkRead(t, srv, []byte("a third line"), nil)
 	<-c
 	go srv.Close()
-	checkRead(t, cli, nil, os.EOF)
+	checkRead(t, cli, nil, io.EOF)
 	cli.Close()
 }

diff --git a/src/pkg/net/port.go b/src/pkg/net/port.go
index a8ca60c..80597f7 100644
--- a/src/pkg/net/port.go
+++ b/src/pkg/net/port.go

@@ -8,13 +8,10 @@
 
 package net
 
-import (
-	"os"
-	"sync"
-)
+import "sync"
 
 var services map[string]map[string]int
-var servicesError os.Error
+var servicesError error
 var onceReadServices sync.Once
 
 func readServices() {
@@ -53,7 +50,7 @@
 }
 
 // goLookupPort is the native Go implementation of LookupPort.
-func goLookupPort(network, service string) (port int, err os.Error) {
+func goLookupPort(network, service string) (port int, err error) {
 	onceReadServices.Do(readServices)
 
 	switch network {

diff --git a/src/pkg/net/sendfile_linux.go b/src/pkg/net/sendfile_linux.go
index 6a5a06c..36c7578 100644
--- a/src/pkg/net/sendfile_linux.go
+++ b/src/pkg/net/sendfile_linux.go

@@ -21,7 +21,7 @@
 // non-EOF error.
 //
 // if handled == false, sendFile performed no work.
-func sendFile(c *netFD, r io.Reader) (written int64, err os.Error, handled bool) {
+func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 	var remain int64 = 1 << 62 // by default, copy until EOF
 
 	lr, ok := r.(*io.LimitedReader)

diff --git a/src/pkg/net/sendfile_stub.go b/src/pkg/net/sendfile_stub.go
index c55be6c..b0adea4 100644
--- a/src/pkg/net/sendfile_stub.go
+++ b/src/pkg/net/sendfile_stub.go

@@ -6,11 +6,8 @@
 
 package net
 
-import (
-	"io"
-	"os"
-)
+import "io"
 
-func sendFile(c *netFD, r io.Reader) (n int64, err os.Error, handled bool) {
+func sendFile(c *netFD, r io.Reader) (n int64, err error, handled bool) {
 	return 0, nil, false
 }

diff --git a/src/pkg/net/sendfile_windows.go b/src/pkg/net/sendfile_windows.go
index d9c2f53..0b31572 100644
--- a/src/pkg/net/sendfile_windows.go
+++ b/src/pkg/net/sendfile_windows.go

@@ -33,7 +33,7 @@
 // if handled == false, sendFile performed no work.
 //
 // Note that sendfile for windows does not suppport >2GB file.
-func sendFile(c *netFD, r io.Reader) (written int64, err os.Error, handled bool) {
+func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 	var n int64 = 0 // by default, copy until EOF
 
 	lr, ok := r.(*io.LimitedReader)

diff --git a/src/pkg/net/server_test.go b/src/pkg/net/server_test.go
index a2ff218..9e54449 100644
--- a/src/pkg/net/server_test.go
+++ b/src/pkg/net/server_test.go

@@ -55,7 +55,7 @@
 
 func connect(t *testing.T, network, addr string, isEmpty bool) {
 	var fd Conn
-	var err os.Error
+	var err error
 	if network == "unixgram" {
 		fd, err = DialUnix(network, &UnixAddr{addr + ".local", network}, &UnixAddr{addr, network})
 	} else {

diff --git a/src/pkg/net/sock.go b/src/pkg/net/sock.go
index 2359014..d9df02c 100644
--- a/src/pkg/net/sock.go
+++ b/src/pkg/net/sock.go

@@ -24,7 +24,7 @@
 }
 
 // Generic socket creation.
-func socket(net string, f, p, t int, la, ra syscall.Sockaddr, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err os.Error) {
+func socket(net string, f, p, t int, la, ra syscall.Sockaddr, toAddr func(syscall.Sockaddr) Addr) (fd *netFD, err error) {
 	// See ../syscall/exec.go for description of ForkLock.
 	syscall.ForkLock.RLock()
 	s, e := syscall.Socket(f, p, t)
@@ -67,74 +67,74 @@
 	return fd, nil
 }
 
-func setsockoptInt(fd *netFD, level, opt int, value int) os.Error {
+func setsockoptInt(fd *netFD, level, opt int, value int) error {
 	return os.NewSyscallError("setsockopt", syscall.SetsockoptInt(fd.sysfd, level, opt, value))
 }
 
-func setsockoptNsec(fd *netFD, level, opt int, nsec int64) os.Error {
+func setsockoptNsec(fd *netFD, level, opt int, nsec int64) error {
 	var tv = syscall.NsecToTimeval(nsec)
 	return os.NewSyscallError("setsockopt", syscall.SetsockoptTimeval(fd.sysfd, level, opt, &tv))
 }
 
-func setReadBuffer(fd *netFD, bytes int) os.Error {
+func setReadBuffer(fd *netFD, bytes int) error {
 	fd.incref()
 	defer fd.decref()
 	return setsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_RCVBUF, bytes)
 }
 
-func setWriteBuffer(fd *netFD, bytes int) os.Error {
+func setWriteBuffer(fd *netFD, bytes int) error {
 	fd.incref()
 	defer fd.decref()
 	return setsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_SNDBUF, bytes)
 }
 
-func setReadTimeout(fd *netFD, nsec int64) os.Error {
+func setReadTimeout(fd *netFD, nsec int64) error {
 	fd.rdeadline_delta = nsec
 	return nil
 }
 
-func setWriteTimeout(fd *netFD, nsec int64) os.Error {
+func setWriteTimeout(fd *netFD, nsec int64) error {
 	fd.wdeadline_delta = nsec
 	return nil
 }
 
-func setTimeout(fd *netFD, nsec int64) os.Error {
+func setTimeout(fd *netFD, nsec int64) error {
 	if e := setReadTimeout(fd, nsec); e != nil {
 		return e
 	}
 	return setWriteTimeout(fd, nsec)
 }
 
-func setReuseAddr(fd *netFD, reuse bool) os.Error {
+func setReuseAddr(fd *netFD, reuse bool) error {
 	fd.incref()
 	defer fd.decref()
 	return setsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, boolint(reuse))
 }
 
-func bindToDevice(fd *netFD, dev string) os.Error {
+func bindToDevice(fd *netFD, dev string) error {
 	// TODO(rsc): call setsockopt with null-terminated string pointer
 	return os.EINVAL
 }
 
-func setDontRoute(fd *netFD, dontroute bool) os.Error {
+func setDontRoute(fd *netFD, dontroute bool) error {
 	fd.incref()
 	defer fd.decref()
 	return setsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_DONTROUTE, boolint(dontroute))
 }
 
-func setKeepAlive(fd *netFD, keepalive bool) os.Error {
+func setKeepAlive(fd *netFD, keepalive bool) error {
 	fd.incref()
 	defer fd.decref()
 	return setsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, boolint(keepalive))
 }
 
-func setNoDelay(fd *netFD, noDelay bool) os.Error {
+func setNoDelay(fd *netFD, noDelay bool) error {
 	fd.incref()
 	defer fd.decref()
 	return setsockoptInt(fd, syscall.IPPROTO_TCP, syscall.TCP_NODELAY, boolint(noDelay))
 }
 
-func setLinger(fd *netFD, sec int) os.Error {
+func setLinger(fd *netFD, sec int) error {
 	var l syscall.Linger
 	if sec >= 0 {
 		l.Onoff = 1
@@ -153,7 +153,7 @@
 	sa syscall.Sockaddr
 }
 
-func (e *UnknownSocketError) String() string {
+func (e *UnknownSocketError) Error() string {
 	return "unknown socket address type " + reflect.TypeOf(e.sa).String()
 }
 
@@ -163,7 +163,7 @@
 
 // Fallback implementation of io.ReaderFrom's ReadFrom, when sendfile isn't
 // applicable.
-func genericReadFrom(w io.Writer, r io.Reader) (n int64, err os.Error) {
+func genericReadFrom(w io.Writer, r io.Reader) (n int64, err error) {
 	// Use wrapper to hide existing r.ReadFrom from io.Copy.
 	return io.Copy(writerOnly{w}, r)
 }

diff --git a/src/pkg/net/tcpsock.go b/src/pkg/net/tcpsock.go
index f5c0a27..47fbf29 100644
--- a/src/pkg/net/tcpsock.go
+++ b/src/pkg/net/tcpsock.go

@@ -6,10 +6,6 @@
 
 package net
 
-import (
-	"os"
-)
-
 // TCPAddr represents the address of a TCP end point.
 type TCPAddr struct {
 	IP   IP
@@ -31,7 +27,7 @@
 // numeric addresses on the network net, which must be "tcp",
 // "tcp4" or "tcp6".  A literal IPv6 host address must be
 // enclosed in square brackets, as in "[::]:80".
-func ResolveTCPAddr(net, addr string) (*TCPAddr, os.Error) {
+func ResolveTCPAddr(net, addr string) (*TCPAddr, error) {
 	ip, port, err := hostPortToIP(net, addr)
 	if err != nil {
 		return nil, err

diff --git a/src/pkg/net/tcpsock_plan9.go b/src/pkg/net/tcpsock_plan9.go
index 3319e57..69fae03 100644
--- a/src/pkg/net/tcpsock_plan9.go
+++ b/src/pkg/net/tcpsock_plan9.go

@@ -18,7 +18,7 @@
 
 // CloseRead shuts down the reading side of the TCP connection.
 // Most callers should just use Close.
-func (c *TCPConn) CloseRead() os.Error {
+func (c *TCPConn) CloseRead() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -27,7 +27,7 @@
 
 // CloseWrite shuts down the writing side of the TCP connection.
 // Most callers should just use Close.
-func (c *TCPConn) CloseWrite() os.Error {
+func (c *TCPConn) CloseWrite() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -37,7 +37,7 @@
 // DialTCP connects to the remote address raddr on the network net,
 // which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is used
 // as the local address for the connection.
-func DialTCP(net string, laddr, raddr *TCPAddr) (c *TCPConn, err os.Error) {
+func DialTCP(net string, laddr, raddr *TCPAddr) (c *TCPConn, err error) {
 	switch net {
 	case "tcp", "tcp4", "tcp6":
 	default:
@@ -64,7 +64,7 @@
 // Net must be "tcp", "tcp4", or "tcp6".
 // If laddr has a port of 0, it means to listen on some available port.
 // The caller can use l.Addr() to retrieve the chosen address.
-func ListenTCP(net string, laddr *TCPAddr) (l *TCPListener, err os.Error) {
+func ListenTCP(net string, laddr *TCPAddr) (l *TCPListener, err error) {
 	switch net {
 	case "tcp", "tcp4", "tcp6":
 	default:

diff --git a/src/pkg/net/tcpsock_posix.go b/src/pkg/net/tcpsock_posix.go
index 740a63d..a726b45 100644
--- a/src/pkg/net/tcpsock_posix.go
+++ b/src/pkg/net/tcpsock_posix.go

@@ -39,7 +39,7 @@
 	return syscall.AF_INET6
 }
 
-func (a *TCPAddr) sockaddr(family int) (syscall.Sockaddr, os.Error) {
+func (a *TCPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
 	return ipToSockaddr(family, a.IP, a.Port)
 }
 
@@ -67,7 +67,7 @@
 // Implementation of the Conn interface - see Conn for documentation.
 
 // Read implements the net.Conn Read method.
-func (c *TCPConn) Read(b []byte) (n int, err os.Error) {
+func (c *TCPConn) Read(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -75,7 +75,7 @@
 }
 
 // ReadFrom implements the io.ReaderFrom ReadFrom method.
-func (c *TCPConn) ReadFrom(r io.Reader) (int64, os.Error) {
+func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) {
 	if n, err, handled := sendFile(c.fd, r); handled {
 		return n, err
 	}
@@ -83,7 +83,7 @@
 }
 
 // Write implements the net.Conn Write method.
-func (c *TCPConn) Write(b []byte) (n int, err os.Error) {
+func (c *TCPConn) Write(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -91,7 +91,7 @@
 }
 
 // Close closes the TCP connection.
-func (c *TCPConn) Close() os.Error {
+func (c *TCPConn) Close() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -102,7 +102,7 @@
 
 // CloseRead shuts down the reading side of the TCP connection.
 // Most callers should just use Close.
-func (c *TCPConn) CloseRead() os.Error {
+func (c *TCPConn) CloseRead() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -111,7 +111,7 @@
 
 // CloseWrite shuts down the writing side of the TCP connection.
 // Most callers should just use Close.
-func (c *TCPConn) CloseWrite() os.Error {
+func (c *TCPConn) CloseWrite() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -135,7 +135,7 @@
 }
 
 // SetTimeout implements the net.Conn SetTimeout method.
-func (c *TCPConn) SetTimeout(nsec int64) os.Error {
+func (c *TCPConn) SetTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -143,7 +143,7 @@
 }
 
 // SetReadTimeout implements the net.Conn SetReadTimeout method.
-func (c *TCPConn) SetReadTimeout(nsec int64) os.Error {
+func (c *TCPConn) SetReadTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -151,7 +151,7 @@
 }
 
 // SetWriteTimeout implements the net.Conn SetWriteTimeout method.
-func (c *TCPConn) SetWriteTimeout(nsec int64) os.Error {
+func (c *TCPConn) SetWriteTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -160,7 +160,7 @@
 
 // SetReadBuffer sets the size of the operating system's
 // receive buffer associated with the connection.
-func (c *TCPConn) SetReadBuffer(bytes int) os.Error {
+func (c *TCPConn) SetReadBuffer(bytes int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -169,7 +169,7 @@
 
 // SetWriteBuffer sets the size of the operating system's
 // transmit buffer associated with the connection.
-func (c *TCPConn) SetWriteBuffer(bytes int) os.Error {
+func (c *TCPConn) SetWriteBuffer(bytes int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -187,7 +187,7 @@
 //
 // If sec > 0, Close blocks for at most sec seconds waiting for
 // data to be sent and acknowledged.
-func (c *TCPConn) SetLinger(sec int) os.Error {
+func (c *TCPConn) SetLinger(sec int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -196,7 +196,7 @@
 
 // SetKeepAlive sets whether the operating system should send
 // keepalive messages on the connection.
-func (c *TCPConn) SetKeepAlive(keepalive bool) os.Error {
+func (c *TCPConn) SetKeepAlive(keepalive bool) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -207,7 +207,7 @@
 // packet transmission in hopes of sending fewer packets
 // (Nagle's algorithm).  The default is true (no delay), meaning
 // that data is sent as soon as possible after a Write.
-func (c *TCPConn) SetNoDelay(noDelay bool) os.Error {
+func (c *TCPConn) SetNoDelay(noDelay bool) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -217,12 +217,12 @@
 // File returns a copy of the underlying os.File, set to blocking mode.
 // It is the caller's responsibility to close f when finished.
 // Closing c does not affect f, and closing f does not affect c.
-func (c *TCPConn) File() (f *os.File, err os.Error) { return c.fd.dup() }
+func (c *TCPConn) File() (f *os.File, err error) { return c.fd.dup() }
 
 // DialTCP connects to the remote address raddr on the network net,
 // which must be "tcp", "tcp4", or "tcp6".  If laddr is not nil, it is used
 // as the local address for the connection.
-func DialTCP(net string, laddr, raddr *TCPAddr) (c *TCPConn, err os.Error) {
+func DialTCP(net string, laddr, raddr *TCPAddr) (c *TCPConn, err error) {
 	if raddr == nil {
 		return nil, &OpError{"dial", "tcp", nil, errMissingAddress}
 	}
@@ -244,7 +244,7 @@
 // Net must be "tcp", "tcp4", or "tcp6".
 // If laddr has a port of 0, it means to listen on some available port.
 // The caller can use l.Addr() to retrieve the chosen address.
-func ListenTCP(net string, laddr *TCPAddr) (l *TCPListener, err os.Error) {
+func ListenTCP(net string, laddr *TCPAddr) (l *TCPListener, err error) {
 	fd, err := internetSocket(net, laddr.toAddr(), nil, syscall.SOCK_STREAM, 0, "listen", sockaddrToTCP)
 	if err != nil {
 		return nil, err
@@ -261,7 +261,7 @@
 
 // AcceptTCP accepts the next incoming call and returns the new connection
 // and the remote address.
-func (l *TCPListener) AcceptTCP() (c *TCPConn, err os.Error) {
+func (l *TCPListener) AcceptTCP() (c *TCPConn, err error) {
 	if l == nil || l.fd == nil || l.fd.sysfd < 0 {
 		return nil, os.EINVAL
 	}
@@ -274,7 +274,7 @@
 
 // Accept implements the Accept method in the Listener interface;
 // it waits for the next call and returns a generic Conn.
-func (l *TCPListener) Accept() (c Conn, err os.Error) {
+func (l *TCPListener) Accept() (c Conn, err error) {
 	c1, err := l.AcceptTCP()
 	if err != nil {
 		return nil, err
@@ -284,7 +284,7 @@
 
 // Close stops listening on the TCP address.
 // Already Accepted connections are not closed.
-func (l *TCPListener) Close() os.Error {
+func (l *TCPListener) Close() error {
 	if l == nil || l.fd == nil {
 		return os.EINVAL
 	}
@@ -295,7 +295,7 @@
 func (l *TCPListener) Addr() Addr { return l.fd.laddr }
 
 // SetTimeout sets the deadline associated with the listener
-func (l *TCPListener) SetTimeout(nsec int64) os.Error {
+func (l *TCPListener) SetTimeout(nsec int64) error {
 	if l == nil || l.fd == nil {
 		return os.EINVAL
 	}
@@ -305,4 +305,4 @@
 // File returns a copy of the underlying os.File, set to blocking mode.
 // It is the caller's responsibility to close f when finished.
 // Closing c does not affect f, and closing f does not affect c.
-func (l *TCPListener) File() (f *os.File, err os.Error) { return l.fd.dup() }
+func (l *TCPListener) File() (f *os.File, err error) { return l.fd.dup() }

diff --git a/src/pkg/net/textproto/reader.go b/src/pkg/net/textproto/reader.go
index 98b3927..658b5c2 100644
--- a/src/pkg/net/textproto/reader.go
+++ b/src/pkg/net/textproto/reader.go

@@ -9,7 +9,6 @@
 	"bytes"
 	"io"
 	"io/ioutil"
-	"os"
 	"strconv"
 	"strings"
 )
@@ -32,13 +31,13 @@
 
 // ReadLine reads a single line from r,
 // eliding the final \n or \r\n from the returned string.
-func (r *Reader) ReadLine() (string, os.Error) {
+func (r *Reader) ReadLine() (string, error) {
 	line, err := r.readLineSlice()
 	return string(line), err
 }
 
 // ReadLineBytes is like ReadLine but returns a []byte instead of a string.
-func (r *Reader) ReadLineBytes() ([]byte, os.Error) {
+func (r *Reader) ReadLineBytes() ([]byte, error) {
 	line, err := r.readLineSlice()
 	if line != nil {
 		buf := make([]byte, len(line))
@@ -48,7 +47,7 @@
 	return line, err
 }
 
-func (r *Reader) readLineSlice() ([]byte, os.Error) {
+func (r *Reader) readLineSlice() ([]byte, error) {
 	r.closeDot()
 	var line []byte
 	for {
@@ -87,7 +86,7 @@
 //
 // A line consisting of only white space is never continued.
 //
-func (r *Reader) ReadContinuedLine() (string, os.Error) {
+func (r *Reader) ReadContinuedLine() (string, error) {
 	line, err := r.readContinuedLineSlice()
 	return string(line), err
 }
@@ -108,7 +107,7 @@
 
 // ReadContinuedLineBytes is like ReadContinuedLine but
 // returns a []byte instead of a string.
-func (r *Reader) ReadContinuedLineBytes() ([]byte, os.Error) {
+func (r *Reader) ReadContinuedLineBytes() ([]byte, error) {
 	line, err := r.readContinuedLineSlice()
 	if line != nil {
 		buf := make([]byte, len(line))
@@ -118,7 +117,7 @@
 	return line, err
 }
 
-func (r *Reader) readContinuedLineSlice() ([]byte, os.Error) {
+func (r *Reader) readContinuedLineSlice() ([]byte, error) {
 	// Read the first line.
 	line, err := r.readLineSlice()
 	if err != nil {
@@ -192,7 +191,7 @@
 	return line, err
 }
 
-func (r *Reader) readCodeLine(expectCode int) (code int, continued bool, message string, err os.Error) {
+func (r *Reader) readCodeLine(expectCode int) (code int, continued bool, message string, err error) {
 	line, err := r.ReadLine()
 	if err != nil {
 		return
@@ -200,7 +199,7 @@
 	return parseCodeLine(line, expectCode)
 }
 
-func parseCodeLine(line string, expectCode int) (code int, continued bool, message string, err os.Error) {
+func parseCodeLine(line string, expectCode int) (code int, continued bool, message string, err error) {
 	if len(line) < 4 || line[3] != ' ' && line[3] != '-' {
 		err = ProtocolError("short response: " + line)
 		return
@@ -235,7 +234,7 @@
 //
 // An expectCode <= 0 disables the check of the status code.
 //
-func (r *Reader) ReadCodeLine(expectCode int) (code int, message string, err os.Error) {
+func (r *Reader) ReadCodeLine(expectCode int) (code int, message string, err error) {
 	code, continued, message, err := r.readCodeLine(expectCode)
 	if err == nil && continued {
 		err = ProtocolError("unexpected multi-line response: " + message)
@@ -265,7 +264,7 @@
 //
 // An expectCode <= 0 disables the check of the status code.
 //
-func (r *Reader) ReadResponse(expectCode int) (code int, message string, err os.Error) {
+func (r *Reader) ReadResponse(expectCode int) (code int, message string, err error) {
 	code, continued, message, err := r.readCodeLine(expectCode)
 	for err == nil && continued {
 		line, err := r.ReadLine()
@@ -314,7 +313,7 @@
 }
 
 // Read satisfies reads by decoding dot-encoded data read from d.r.
-func (d *dotReader) Read(b []byte) (n int, err os.Error) {
+func (d *dotReader) Read(b []byte) (n int, err error) {
 	// Run data through a simple state machine to
 	// elide leading dots, rewrite trailing \r\n into \n,
 	// and detect ending .\r\n line.
@@ -331,7 +330,7 @@
 		var c byte
 		c, err = br.ReadByte()
 		if err != nil {
-			if err == os.EOF {
+			if err == io.EOF {
 				err = io.ErrUnexpectedEOF
 			}
 			break
@@ -393,7 +392,7 @@
 		n++
 	}
 	if err == nil && d.state == stateEOF {
-		err = os.EOF
+		err = io.EOF
 	}
 	if err != nil && d.r.dot == d {
 		d.r.dot = nil
@@ -418,7 +417,7 @@
 // ReadDotBytes reads a dot-encoding and returns the decoded data.
 //
 // See the documentation for the DotReader method for details about dot-encoding.
-func (r *Reader) ReadDotBytes() ([]byte, os.Error) {
+func (r *Reader) ReadDotBytes() ([]byte, error) {
 	return ioutil.ReadAll(r.DotReader())
 }
 
@@ -426,17 +425,17 @@
 // containing the decoded lines, with the final \r\n or \n elided from each.
 //
 // See the documentation for the DotReader method for details about dot-encoding.
-func (r *Reader) ReadDotLines() ([]string, os.Error) {
+func (r *Reader) ReadDotLines() ([]string, error) {
 	// We could use ReadDotBytes and then Split it,
 	// but reading a line at a time avoids needing a
 	// large contiguous block of memory and is simpler.
 	var v []string
-	var err os.Error
+	var err error
 	for {
 		var line string
 		line, err = r.ReadLine()
 		if err != nil {
-			if err == os.EOF {
+			if err == io.EOF {
 				err = io.ErrUnexpectedEOF
 			}
 			break
@@ -474,7 +473,7 @@
 //		"Long-Key": {"Even Longer Value"},
 //	}
 //
-func (r *Reader) ReadMIMEHeader() (MIMEHeader, os.Error) {
+func (r *Reader) ReadMIMEHeader() (MIMEHeader, error) {
 	m := make(MIMEHeader)
 	for {
 		kv, err := r.readContinuedLineSlice()

diff --git a/src/pkg/net/textproto/reader_test.go b/src/pkg/net/textproto/reader_test.go
index a087e29..5aefe39 100644
--- a/src/pkg/net/textproto/reader_test.go
+++ b/src/pkg/net/textproto/reader_test.go

@@ -7,7 +7,6 @@
 import (
 	"bufio"
 	"io"
-	"os"
 	"reflect"
 	"strings"
 	"testing"
@@ -49,7 +48,7 @@
 		t.Fatalf("Line 2: %s, %v", s, err)
 	}
 	s, err = r.ReadLine()
-	if s != "" || err != os.EOF {
+	if s != "" || err != io.EOF {
 		t.Fatalf("EOF: %s, %v", s, err)
 	}
 }
@@ -69,7 +68,7 @@
 		t.Fatalf("Line 3: %s, %v", s, err)
 	}
 	s, err = r.ReadContinuedLine()
-	if s != "" || err != os.EOF {
+	if s != "" || err != io.EOF {
 		t.Fatalf("EOF: %s, %v", s, err)
 	}
 }
@@ -92,7 +91,7 @@
 		t.Fatalf("Line 3: wrong error %v\n", err)
 	}
 	code, msg, err = r.ReadCodeLine(1)
-	if code != 0 || msg != "" || err != os.EOF {
+	if code != 0 || msg != "" || err != io.EOF {
 		t.Fatalf("EOF: %d, %s, %v", code, msg, err)
 	}
 }

diff --git a/src/pkg/net/textproto/textproto.go b/src/pkg/net/textproto/textproto.go
index 9f19b54..317ec72 100644
--- a/src/pkg/net/textproto/textproto.go
+++ b/src/pkg/net/textproto/textproto.go

@@ -27,7 +27,6 @@
 	"fmt"
 	"io"
 	"net"
-	"os"
 )
 
 // An Error represents a numeric error response from a server.
@@ -36,7 +35,7 @@
 	Msg  string
 }
 
-func (e *Error) String() string {
+func (e *Error) Error() string {
 	return fmt.Sprintf("%03d %s", e.Code, e.Msg)
 }
 
@@ -44,7 +43,7 @@
 // as an invalid response or a hung-up connection.
 type ProtocolError string
 
-func (p ProtocolError) String() string {
+func (p ProtocolError) Error() string {
 	return string(p)
 }
 
@@ -70,13 +69,13 @@
 }
 
 // Close closes the connection.
-func (c *Conn) Close() os.Error {
+func (c *Conn) Close() error {
 	return c.conn.Close()
 }
 
 // Dial connects to the given address on the given network using net.Dial
 // and then returns a new Conn for the connection.
-func Dial(network, addr string) (*Conn, os.Error) {
+func Dial(network, addr string) (*Conn, error) {
 	c, err := net.Dial(network, addr)
 	if err != nil {
 		return nil, err
@@ -109,7 +108,7 @@
 //	}
 //	return c.ReadCodeLine(250)
 //
-func (c *Conn) Cmd(format string, args ...interface{}) (id uint, err os.Error) {
+func (c *Conn) Cmd(format string, args ...interface{}) (id uint, err error) {
 	id = c.Next()
 	c.StartRequest(id)
 	err = c.PrintfLine(format, args...)

diff --git a/src/pkg/net/textproto/writer.go b/src/pkg/net/textproto/writer.go
index 4e705f6..03e2fd6 100644
--- a/src/pkg/net/textproto/writer.go
+++ b/src/pkg/net/textproto/writer.go

@@ -8,7 +8,6 @@
 	"bufio"
 	"fmt"
 	"io"
-	"os"
 )
 
 // A Writer implements convenience methods for writing
@@ -27,7 +26,7 @@
 var dotcrnl = []byte{'.', '\r', '\n'}
 
 // PrintfLine writes the formatted output followed by \r\n.
-func (w *Writer) PrintfLine(format string, args ...interface{}) os.Error {
+func (w *Writer) PrintfLine(format string, args ...interface{}) error {
 	w.closeDot()
 	fmt.Fprintf(w.W, format, args...)
 	w.W.Write(crnl)
@@ -64,7 +63,7 @@
 	wstateData             // writing data in middle of line
 )
 
-func (d *dotWriter) Write(b []byte) (n int, err os.Error) {
+func (d *dotWriter) Write(b []byte) (n int, err error) {
 	bw := d.w.W
 	for n < len(b) {
 		c := b[n]
@@ -100,7 +99,7 @@
 	return
 }
 
-func (d *dotWriter) Close() os.Error {
+func (d *dotWriter) Close() error {
 	if d.w.dot == d {
 		d.w.dot = nil
 	}

diff --git a/src/pkg/net/timeout_test.go b/src/pkg/net/timeout_test.go
index 2c2c36f..3c884ca 100644
--- a/src/pkg/net/timeout_test.go
+++ b/src/pkg/net/timeout_test.go

@@ -5,7 +5,6 @@
 package net
 
 import (
-	"os"
 	"runtime"
 	"testing"
 	"time"
@@ -22,7 +21,7 @@
 	fd.SetReadTimeout(1e8) // 100ms
 	var b [100]byte
 	var n int
-	var err1 os.Error
+	var err1 error
 	if readFrom {
 		n, _, err1 = fd.(PacketConn).ReadFrom(b[0:])
 	} else {

diff --git a/src/pkg/net/udpsock.go b/src/pkg/net/udpsock.go
index 3dfa716..b3520cf 100644
--- a/src/pkg/net/udpsock.go
+++ b/src/pkg/net/udpsock.go

@@ -6,10 +6,6 @@
 
 package net
 
-import (
-	"os"
-)
-
 // UDPAddr represents the address of a UDP end point.
 type UDPAddr struct {
 	IP   IP
@@ -31,7 +27,7 @@
 // numeric addresses on the network net, which must be "udp",
 // "udp4" or "udp6".  A literal IPv6 host address must be
 // enclosed in square brackets, as in "[::]:80".
-func ResolveUDPAddr(net, addr string) (*UDPAddr, os.Error) {
+func ResolveUDPAddr(net, addr string) (*UDPAddr, error) {
 	ip, port, err := hostPortToIP(net, addr)
 	if err != nil {
 		return nil, err

diff --git a/src/pkg/net/udpsock_plan9.go b/src/pkg/net/udpsock_plan9.go
index d5c6ccb..60dec81 100644
--- a/src/pkg/net/udpsock_plan9.go
+++ b/src/pkg/net/udpsock_plan9.go

@@ -7,6 +7,7 @@
 package net
 
 import (
+	"errors"
 	"os"
 )
 
@@ -24,7 +25,7 @@
 //
 // ReadFromUDP can be made to time out and return an error with Timeout() == true
 // after a fixed time limit; see SetTimeout and SetReadTimeout.
-func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err os.Error) {
+func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
 	if !c.ok() {
 		return 0, nil, os.EINVAL
 	}
@@ -40,7 +41,7 @@
 		return
 	}
 	if m < udpHeaderSize {
-		return 0, nil, os.NewError("short read reading UDP header")
+		return 0, nil, errors.New("short read reading UDP header")
 	}
 	buf = buf[:m]
 
@@ -50,7 +51,7 @@
 }
 
 // ReadFrom implements the net.PacketConn ReadFrom method.
-func (c *UDPConn) ReadFrom(b []byte) (n int, addr Addr, err os.Error) {
+func (c *UDPConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
 	if !c.ok() {
 		return 0, nil, os.EINVAL
 	}
@@ -63,7 +64,7 @@
 // an error with Timeout() == true after a fixed time limit;
 // see SetTimeout and SetWriteTimeout.
 // On packet-oriented connections, write timeouts are rare.
-func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (n int, err os.Error) {
+func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -87,7 +88,7 @@
 }
 
 // WriteTo implements the net.PacketConn WriteTo method.
-func (c *UDPConn) WriteTo(b []byte, addr Addr) (n int, err os.Error) {
+func (c *UDPConn) WriteTo(b []byte, addr Addr) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -101,7 +102,7 @@
 // DialUDP connects to the remote address raddr on the network net,
 // which must be "udp", "udp4", or "udp6".  If laddr is not nil, it is used
 // as the local address for the connection.
-func DialUDP(net string, laddr, raddr *UDPAddr) (c *UDPConn, err os.Error) {
+func DialUDP(net string, laddr, raddr *UDPAddr) (c *UDPConn, err error) {
 	switch net {
 	case "udp", "udp4", "udp6":
 	default:
@@ -149,7 +150,7 @@
 // local address laddr.  The returned connection c's ReadFrom
 // and WriteTo methods can be used to receive and send UDP
 // packets with per-packet addressing.
-func ListenUDP(net string, laddr *UDPAddr) (c *UDPConn, err os.Error) {
+func ListenUDP(net string, laddr *UDPAddr) (c *UDPConn, err error) {
 	switch net {
 	case "udp", "udp4", "udp6":
 	default:
@@ -172,7 +173,7 @@
 // JoinGroup joins the IP multicast group named by addr on ifi,
 // which specifies the interface to join.  JoinGroup uses the
 // default multicast interface if ifi is nil.
-func (c *UDPConn) JoinGroup(ifi *Interface, addr IP) os.Error {
+func (c *UDPConn) JoinGroup(ifi *Interface, addr IP) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -180,7 +181,7 @@
 }
 
 // LeaveGroup exits the IP multicast group named by addr on ifi.
-func (c *UDPConn) LeaveGroup(ifi *Interface, addr IP) os.Error {
+func (c *UDPConn) LeaveGroup(ifi *Interface, addr IP) error {
 	if !c.ok() {
 		return os.EINVAL
 	}

diff --git a/src/pkg/net/udpsock_posix.go b/src/pkg/net/udpsock_posix.go
index 06298ee..2cfcc60 100644
--- a/src/pkg/net/udpsock_posix.go
+++ b/src/pkg/net/udpsock_posix.go

@@ -34,7 +34,7 @@
 	return syscall.AF_INET6
 }
 
-func (a *UDPAddr) sockaddr(family int) (syscall.Sockaddr, os.Error) {
+func (a *UDPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
 	return ipToSockaddr(family, a.IP, a.Port)
 }
 
@@ -58,7 +58,7 @@
 // Implementation of the Conn interface - see Conn for documentation.
 
 // Read implements the net.Conn Read method.
-func (c *UDPConn) Read(b []byte) (n int, err os.Error) {
+func (c *UDPConn) Read(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -66,7 +66,7 @@
 }
 
 // Write implements the net.Conn Write method.
-func (c *UDPConn) Write(b []byte) (n int, err os.Error) {
+func (c *UDPConn) Write(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -74,7 +74,7 @@
 }
 
 // Close closes the UDP connection.
-func (c *UDPConn) Close() os.Error {
+func (c *UDPConn) Close() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -100,7 +100,7 @@
 }
 
 // SetTimeout implements the net.Conn SetTimeout method.
-func (c *UDPConn) SetTimeout(nsec int64) os.Error {
+func (c *UDPConn) SetTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -108,7 +108,7 @@
 }
 
 // SetReadTimeout implements the net.Conn SetReadTimeout method.
-func (c *UDPConn) SetReadTimeout(nsec int64) os.Error {
+func (c *UDPConn) SetReadTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -116,7 +116,7 @@
 }
 
 // SetWriteTimeout implements the net.Conn SetWriteTimeout method.
-func (c *UDPConn) SetWriteTimeout(nsec int64) os.Error {
+func (c *UDPConn) SetWriteTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -125,7 +125,7 @@
 
 // SetReadBuffer sets the size of the operating system's
 // receive buffer associated with the connection.
-func (c *UDPConn) SetReadBuffer(bytes int) os.Error {
+func (c *UDPConn) SetReadBuffer(bytes int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -134,7 +134,7 @@
 
 // SetWriteBuffer sets the size of the operating system's
 // transmit buffer associated with the connection.
-func (c *UDPConn) SetWriteBuffer(bytes int) os.Error {
+func (c *UDPConn) SetWriteBuffer(bytes int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -149,7 +149,7 @@
 //
 // ReadFromUDP can be made to time out and return an error with Timeout() == true
 // after a fixed time limit; see SetTimeout and SetReadTimeout.
-func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err os.Error) {
+func (c *UDPConn) ReadFromUDP(b []byte) (n int, addr *UDPAddr, err error) {
 	if !c.ok() {
 		return 0, nil, os.EINVAL
 	}
@@ -164,7 +164,7 @@
 }
 
 // ReadFrom implements the net.PacketConn ReadFrom method.
-func (c *UDPConn) ReadFrom(b []byte) (n int, addr Addr, err os.Error) {
+func (c *UDPConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
 	if !c.ok() {
 		return 0, nil, os.EINVAL
 	}
@@ -178,19 +178,19 @@
 // an error with Timeout() == true after a fixed time limit;
 // see SetTimeout and SetWriteTimeout.
 // On packet-oriented connections, write timeouts are rare.
-func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (n int, err os.Error) {
+func (c *UDPConn) WriteToUDP(b []byte, addr *UDPAddr) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
 	sa, err1 := addr.sockaddr(c.fd.family)
 	if err1 != nil {
-		return 0, &OpError{Op: "write", Net: "udp", Addr: addr, Error: err1}
+		return 0, &OpError{Op: "write", Net: "udp", Addr: addr, Err: err1}
 	}
 	return c.fd.WriteTo(b, sa)
 }
 
 // WriteTo implements the net.PacketConn WriteTo method.
-func (c *UDPConn) WriteTo(b []byte, addr Addr) (n int, err os.Error) {
+func (c *UDPConn) WriteTo(b []byte, addr Addr) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -204,7 +204,7 @@
 // DialUDP connects to the remote address raddr on the network net,
 // which must be "udp", "udp4", or "udp6".  If laddr is not nil, it is used
 // as the local address for the connection.
-func DialUDP(net string, laddr, raddr *UDPAddr) (c *UDPConn, err os.Error) {
+func DialUDP(net string, laddr, raddr *UDPAddr) (c *UDPConn, err error) {
 	switch net {
 	case "udp", "udp4", "udp6":
 	default:
@@ -224,7 +224,7 @@
 // local address laddr.  The returned connection c's ReadFrom
 // and WriteTo methods can be used to receive and send UDP
 // packets with per-packet addressing.
-func ListenUDP(net string, laddr *UDPAddr) (c *UDPConn, err os.Error) {
+func ListenUDP(net string, laddr *UDPAddr) (c *UDPConn, err error) {
 	switch net {
 	case "udp", "udp4", "udp6":
 	default:
@@ -241,7 +241,7 @@
 }
 
 // BindToDevice binds a UDPConn to a network interface.
-func (c *UDPConn) BindToDevice(device string) os.Error {
+func (c *UDPConn) BindToDevice(device string) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -253,12 +253,12 @@
 // File returns a copy of the underlying os.File, set to blocking mode.
 // It is the caller's responsibility to close f when finished.
 // Closing c does not affect f, and closing f does not affect c.
-func (c *UDPConn) File() (f *os.File, err os.Error) { return c.fd.dup() }
+func (c *UDPConn) File() (f *os.File, err error) { return c.fd.dup() }
 
 // JoinGroup joins the IP multicast group named by addr on ifi,
 // which specifies the interface to join.  JoinGroup uses the
 // default multicast interface if ifi is nil.
-func (c *UDPConn) JoinGroup(ifi *Interface, addr IP) os.Error {
+func (c *UDPConn) JoinGroup(ifi *Interface, addr IP) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -270,7 +270,7 @@
 }
 
 // LeaveGroup exits the IP multicast group named by addr on ifi.
-func (c *UDPConn) LeaveGroup(ifi *Interface, addr IP) os.Error {
+func (c *UDPConn) LeaveGroup(ifi *Interface, addr IP) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -281,7 +281,7 @@
 	return leaveIPv6GroupUDP(c, ifi, addr)
 }
 
-func joinIPv4GroupUDP(c *UDPConn, ifi *Interface, ip IP) os.Error {
+func joinIPv4GroupUDP(c *UDPConn, ifi *Interface, ip IP) error {
 	mreq := &syscall.IPMreq{Multiaddr: [4]byte{ip[0], ip[1], ip[2], ip[3]}}
 	if err := setIPv4InterfaceToJoin(mreq, ifi); err != nil {
 		return &OpError{"joinipv4group", "udp", &IPAddr{ip}, err}
@@ -292,7 +292,7 @@
 	return nil
 }
 
-func leaveIPv4GroupUDP(c *UDPConn, ifi *Interface, ip IP) os.Error {
+func leaveIPv4GroupUDP(c *UDPConn, ifi *Interface, ip IP) error {
 	mreq := &syscall.IPMreq{Multiaddr: [4]byte{ip[0], ip[1], ip[2], ip[3]}}
 	if err := setIPv4InterfaceToJoin(mreq, ifi); err != nil {
 		return &OpError{"leaveipv4group", "udp", &IPAddr{ip}, err}
@@ -303,7 +303,7 @@
 	return nil
 }
 
-func setIPv4InterfaceToJoin(mreq *syscall.IPMreq, ifi *Interface) os.Error {
+func setIPv4InterfaceToJoin(mreq *syscall.IPMreq, ifi *Interface) error {
 	if ifi == nil {
 		return nil
 	}
@@ -323,7 +323,7 @@
 	return nil
 }
 
-func joinIPv6GroupUDP(c *UDPConn, ifi *Interface, ip IP) os.Error {
+func joinIPv6GroupUDP(c *UDPConn, ifi *Interface, ip IP) error {
 	mreq := &syscall.IPv6Mreq{}
 	copy(mreq.Multiaddr[:], ip)
 	if ifi != nil {
@@ -335,7 +335,7 @@
 	return nil
 }
 
-func leaveIPv6GroupUDP(c *UDPConn, ifi *Interface, ip IP) os.Error {
+func leaveIPv6GroupUDP(c *UDPConn, ifi *Interface, ip IP) error {
 	mreq := &syscall.IPv6Mreq{}
 	copy(mreq.Multiaddr[:], ip)
 	if ifi != nil {

diff --git a/src/pkg/net/unixsock.go b/src/pkg/net/unixsock.go
index d5040f9..ae09569 100644
--- a/src/pkg/net/unixsock.go
+++ b/src/pkg/net/unixsock.go

@@ -6,10 +6,6 @@
 
 package net
 
-import (
-	"os"
-)
-
 // UnixAddr represents the address of a Unix domain socket end point.
 type UnixAddr struct {
 	Name string
@@ -38,7 +34,7 @@
 // ResolveUnixAddr parses addr as a Unix domain socket address.
 // The string net gives the network name, "unix", "unixgram" or
 // "unixpacket".
-func ResolveUnixAddr(net, addr string) (*UnixAddr, os.Error) {
+func ResolveUnixAddr(net, addr string) (*UnixAddr, error) {
 	switch net {
 	case "unix":
 	case "unixpacket":

diff --git a/src/pkg/net/unixsock_plan9.go b/src/pkg/net/unixsock_plan9.go
index 7e212df..ac502d1 100644
--- a/src/pkg/net/unixsock_plan9.go
+++ b/src/pkg/net/unixsock_plan9.go

@@ -17,17 +17,17 @@
 // Implementation of the Conn interface - see Conn for documentation.
 
 // Read implements the net.Conn Read method.
-func (c *UnixConn) Read(b []byte) (n int, err os.Error) {
+func (c *UnixConn) Read(b []byte) (n int, err error) {
 	return 0, os.EPLAN9
 }
 
 // Write implements the net.Conn Write method.
-func (c *UnixConn) Write(b []byte) (n int, err os.Error) {
+func (c *UnixConn) Write(b []byte) (n int, err error) {
 	return 0, os.EPLAN9
 }
 
 // Close closes the Unix domain connection.
-func (c *UnixConn) Close() os.Error {
+func (c *UnixConn) Close() error {
 	return os.EPLAN9
 }
 
@@ -45,28 +45,28 @@
 }
 
 // SetTimeout implements the net.Conn SetTimeout method.
-func (c *UnixConn) SetTimeout(nsec int64) os.Error {
+func (c *UnixConn) SetTimeout(nsec int64) error {
 	return os.EPLAN9
 }
 
 // SetReadTimeout implements the net.Conn SetReadTimeout method.
-func (c *UnixConn) SetReadTimeout(nsec int64) os.Error {
+func (c *UnixConn) SetReadTimeout(nsec int64) error {
 	return os.EPLAN9
 }
 
 // SetWriteTimeout implements the net.Conn SetWriteTimeout method.
-func (c *UnixConn) SetWriteTimeout(nsec int64) os.Error {
+func (c *UnixConn) SetWriteTimeout(nsec int64) error {
 	return os.EPLAN9
 }
 
 // ReadFrom implements the net.PacketConn ReadFrom method.
-func (c *UnixConn) ReadFrom(b []byte) (n int, addr Addr, err os.Error) {
+func (c *UnixConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
 	err = os.EPLAN9
 	return
 }
 
 // WriteTo implements the net.PacketConn WriteTo method.
-func (c *UnixConn) WriteTo(b []byte, addr Addr) (n int, err os.Error) {
+func (c *UnixConn) WriteTo(b []byte, addr Addr) (n int, err error) {
 	err = os.EPLAN9
 	return
 }
@@ -74,7 +74,7 @@
 // DialUnix connects to the remote address raddr on the network net,
 // which must be "unix" or "unixgram".  If laddr is not nil, it is used
 // as the local address for the connection.
-func DialUnix(net string, laddr, raddr *UnixAddr) (c *UnixConn, err os.Error) {
+func DialUnix(net string, laddr, raddr *UnixAddr) (c *UnixConn, err error) {
 	return nil, os.EPLAN9
 }
 
@@ -85,19 +85,19 @@
 
 // ListenUnix announces on the Unix domain socket laddr and returns a Unix listener.
 // Net must be "unix" (stream sockets).
-func ListenUnix(net string, laddr *UnixAddr) (l *UnixListener, err os.Error) {
+func ListenUnix(net string, laddr *UnixAddr) (l *UnixListener, err error) {
 	return nil, os.EPLAN9
 }
 
 // Accept implements the Accept method in the Listener interface;
 // it waits for the next call and returns a generic Conn.
-func (l *UnixListener) Accept() (c Conn, err os.Error) {
+func (l *UnixListener) Accept() (c Conn, err error) {
 	return nil, os.EPLAN9
 }
 
 // Close stops listening on the Unix address.
 // Already accepted connections are not closed.
-func (l *UnixListener) Close() os.Error {
+func (l *UnixListener) Close() error {
 	return os.EPLAN9
 }
 

diff --git a/src/pkg/net/unixsock_posix.go b/src/pkg/net/unixsock_posix.go
index fccf018..6ba692e 100644
--- a/src/pkg/net/unixsock_posix.go
+++ b/src/pkg/net/unixsock_posix.go

@@ -13,7 +13,7 @@
 	"syscall"
 )
 
-func unixSocket(net string, laddr, raddr *UnixAddr, mode string) (fd *netFD, err os.Error) {
+func unixSocket(net string, laddr, raddr *UnixAddr, mode string) (fd *netFD, err error) {
 	var proto int
 	switch net {
 	default:
@@ -38,7 +38,7 @@
 		if raddr != nil {
 			ra = &syscall.SockaddrUnix{Name: raddr.Name}
 		} else if proto != syscall.SOCK_DGRAM || laddr == nil {
-			return nil, &OpError{Op: mode, Net: net, Error: errMissingAddress}
+			return nil, &OpError{Op: mode, Net: net, Err: errMissingAddress}
 		}
 
 	case "listen":
@@ -47,7 +47,7 @@
 		}
 		la = &syscall.SockaddrUnix{Name: laddr.Name}
 		if raddr != nil {
-			return nil, &OpError{Op: mode, Net: net, Addr: raddr, Error: &AddrError{Error: "unexpected remote address", Addr: raddr.String()}}
+			return nil, &OpError{Op: mode, Net: net, Addr: raddr, Err: &AddrError{Err: "unexpected remote address", Addr: raddr.String()}}
 		}
 	}
 
@@ -69,7 +69,7 @@
 	if mode == "listen" {
 		addr = laddr
 	}
-	return nil, &OpError{Op: mode, Net: net, Addr: addr, Error: oserr}
+	return nil, &OpError{Op: mode, Net: net, Addr: addr, Err: oserr}
 }
 
 func sockaddrToUnix(sa syscall.Sockaddr) Addr {
@@ -120,7 +120,7 @@
 // Implementation of the Conn interface - see Conn for documentation.
 
 // Read implements the net.Conn Read method.
-func (c *UnixConn) Read(b []byte) (n int, err os.Error) {
+func (c *UnixConn) Read(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -128,7 +128,7 @@
 }
 
 // Write implements the net.Conn Write method.
-func (c *UnixConn) Write(b []byte) (n int, err os.Error) {
+func (c *UnixConn) Write(b []byte) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -136,7 +136,7 @@
 }
 
 // Close closes the Unix domain connection.
-func (c *UnixConn) Close() os.Error {
+func (c *UnixConn) Close() error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -165,7 +165,7 @@
 }
 
 // SetTimeout implements the net.Conn SetTimeout method.
-func (c *UnixConn) SetTimeout(nsec int64) os.Error {
+func (c *UnixConn) SetTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -173,7 +173,7 @@
 }
 
 // SetReadTimeout implements the net.Conn SetReadTimeout method.
-func (c *UnixConn) SetReadTimeout(nsec int64) os.Error {
+func (c *UnixConn) SetReadTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -181,7 +181,7 @@
 }
 
 // SetWriteTimeout implements the net.Conn SetWriteTimeout method.
-func (c *UnixConn) SetWriteTimeout(nsec int64) os.Error {
+func (c *UnixConn) SetWriteTimeout(nsec int64) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -190,7 +190,7 @@
 
 // SetReadBuffer sets the size of the operating system's
 // receive buffer associated with the connection.
-func (c *UnixConn) SetReadBuffer(bytes int) os.Error {
+func (c *UnixConn) SetReadBuffer(bytes int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -199,7 +199,7 @@
 
 // SetWriteBuffer sets the size of the operating system's
 // transmit buffer associated with the connection.
-func (c *UnixConn) SetWriteBuffer(bytes int) os.Error {
+func (c *UnixConn) SetWriteBuffer(bytes int) error {
 	if !c.ok() {
 		return os.EINVAL
 	}
@@ -213,7 +213,7 @@
 // ReadFromUnix can be made to time out and return
 // an error with Timeout() == true after a fixed time limit;
 // see SetTimeout and SetReadTimeout.
-func (c *UnixConn) ReadFromUnix(b []byte) (n int, addr *UnixAddr, err os.Error) {
+func (c *UnixConn) ReadFromUnix(b []byte) (n int, addr *UnixAddr, err error) {
 	if !c.ok() {
 		return 0, nil, os.EINVAL
 	}
@@ -226,7 +226,7 @@
 }
 
 // ReadFrom implements the net.PacketConn ReadFrom method.
-func (c *UnixConn) ReadFrom(b []byte) (n int, addr Addr, err os.Error) {
+func (c *UnixConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
 	if !c.ok() {
 		return 0, nil, os.EINVAL
 	}
@@ -240,7 +240,7 @@
 // an error with Timeout() == true after a fixed time limit;
 // see SetTimeout and SetWriteTimeout.
 // On packet-oriented connections, write timeouts are rare.
-func (c *UnixConn) WriteToUnix(b []byte, addr *UnixAddr) (n int, err os.Error) {
+func (c *UnixConn) WriteToUnix(b []byte, addr *UnixAddr) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -252,7 +252,7 @@
 }
 
 // WriteTo implements the net.PacketConn WriteTo method.
-func (c *UnixConn) WriteTo(b []byte, addr Addr) (n int, err os.Error) {
+func (c *UnixConn) WriteTo(b []byte, addr Addr) (n int, err error) {
 	if !c.ok() {
 		return 0, os.EINVAL
 	}
@@ -263,7 +263,7 @@
 	return c.WriteToUnix(b, a)
 }
 
-func (c *UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err os.Error) {
+func (c *UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
 	if !c.ok() {
 		return 0, 0, 0, nil, os.EINVAL
 	}
@@ -275,7 +275,7 @@
 	return
 }
 
-func (c *UnixConn) WriteMsgUnix(b, oob []byte, addr *UnixAddr) (n, oobn int, err os.Error) {
+func (c *UnixConn) WriteMsgUnix(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
 	if !c.ok() {
 		return 0, 0, os.EINVAL
 	}
@@ -292,12 +292,12 @@
 // File returns a copy of the underlying os.File, set to blocking mode.
 // It is the caller's responsibility to close f when finished.
 // Closing c does not affect f, and closing f does not affect c.
-func (c *UnixConn) File() (f *os.File, err os.Error) { return c.fd.dup() }
+func (c *UnixConn) File() (f *os.File, err error) { return c.fd.dup() }
 
 // DialUnix connects to the remote address raddr on the network net,
 // which must be "unix" or "unixgram".  If laddr is not nil, it is used
 // as the local address for the connection.
-func DialUnix(net string, laddr, raddr *UnixAddr) (c *UnixConn, err os.Error) {
+func DialUnix(net string, laddr, raddr *UnixAddr) (c *UnixConn, err error) {
 	fd, e := unixSocket(net, laddr, raddr, "dial")
 	if e != nil {
 		return nil, e
@@ -315,7 +315,7 @@
 
 // ListenUnix announces on the Unix domain socket laddr and returns a Unix listener.
 // Net must be "unix" (stream sockets).
-func ListenUnix(net string, laddr *UnixAddr) (l *UnixListener, err os.Error) {
+func ListenUnix(net string, laddr *UnixAddr) (l *UnixListener, err error) {
 	if net != "unix" && net != "unixgram" && net != "unixpacket" {
 		return nil, UnknownNetworkError(net)
 	}
@@ -329,14 +329,14 @@
 	e1 := syscall.Listen(fd.sysfd, 8) // listenBacklog());
 	if e1 != 0 {
 		closesocket(fd.sysfd)
-		return nil, &OpError{Op: "listen", Net: "unix", Addr: laddr, Error: os.Errno(e1)}
+		return nil, &OpError{Op: "listen", Net: "unix", Addr: laddr, Err: os.Errno(e1)}
 	}
 	return &UnixListener{fd, laddr.Name}, nil
 }
 
 // AcceptUnix accepts the next incoming call and returns the new connection
 // and the remote address.
-func (l *UnixListener) AcceptUnix() (c *UnixConn, err os.Error) {
+func (l *UnixListener) AcceptUnix() (c *UnixConn, err error) {
 	if l == nil || l.fd == nil {
 		return nil, os.EINVAL
 	}
@@ -350,7 +350,7 @@
 
 // Accept implements the Accept method in the Listener interface;
 // it waits for the next call and returns a generic Conn.
-func (l *UnixListener) Accept() (c Conn, err os.Error) {
+func (l *UnixListener) Accept() (c Conn, err error) {
 	c1, err := l.AcceptUnix()
 	if err != nil {
 		return nil, err
@@ -360,7 +360,7 @@
 
 // Close stops listening on the Unix address.
 // Already accepted connections are not closed.
-func (l *UnixListener) Close() os.Error {
+func (l *UnixListener) Close() error {
 	if l == nil || l.fd == nil {
 		return os.EINVAL
 	}
@@ -387,7 +387,7 @@
 func (l *UnixListener) Addr() Addr { return l.fd.laddr }
 
 // SetTimeout sets the deadline associated wuth the listener
-func (l *UnixListener) SetTimeout(nsec int64) (err os.Error) {
+func (l *UnixListener) SetTimeout(nsec int64) (err error) {
 	if l == nil || l.fd == nil {
 		return os.EINVAL
 	}
@@ -397,13 +397,13 @@
 // File returns a copy of the underlying os.File, set to blocking mode.
 // It is the caller's responsibility to close f when finished.
 // Closing c does not affect f, and closing f does not affect c.
-func (l *UnixListener) File() (f *os.File, err os.Error) { return l.fd.dup() }
+func (l *UnixListener) File() (f *os.File, err error) { return l.fd.dup() }
 
 // ListenUnixgram listens for incoming Unix datagram packets addressed to the
 // local address laddr.  The returned connection c's ReadFrom
 // and WriteTo methods can be used to receive and send UDP
 // packets with per-packet addressing.  The network net must be "unixgram".
-func ListenUnixgram(net string, laddr *UnixAddr) (c *UDPConn, err os.Error) {
+func ListenUnixgram(net string, laddr *UnixAddr) (c *UDPConn, err error) {
 	switch net {
 	case "unixgram":
 	default: