| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package main |
| |
| import ( |
| "./file" |
| "flag" |
| "fmt" |
| "os" |
| ) |
| |
| func cat(f *file.File) { |
| const NBUF = 512 |
| var buf [NBUF]byte |
| for { |
| switch nr, er := f.Read(buf[:]); true { |
| case nr < 0: |
| fmt.Fprintf(os.Stderr, "cat: error reading from %s: %s\n", f, er) |
| os.Exit(1) |
| case nr == 0: // EOF |
| return |
| case nr > 0: |
| if nw, ew := file.Stdout.Write(buf[0:nr]); nw != nr { |
| fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", f, ew) |
| os.Exit(1) |
| } |
| } |
| } |
| } |
| |
| func main() { |
| flag.Parse() // Scans the arg list and sets up flags |
| if flag.NArg() == 0 { |
| cat(file.Stdin) |
| } |
| for i := 0; i < flag.NArg(); i++ { |
| f, err := file.Open(flag.Arg(i)) |
| if f == nil { |
| fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err) |
| os.Exit(1) |
| } |
| cat(f) |
| f.Close() |
| } |
| } |