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https://github.com/unknwon/the-way-to-go_ZH_CN.git
synced 2025-08-12 05:11:49 +08:00
42 lines
797 B
Go
42 lines
797 B
Go
package main
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import (
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"flag"
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"fmt"
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"os"
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)
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func cat(f *os.File) {
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const NBUF = 512
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var buf [NBUF]byte
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for {
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switch nr, err := f.Read(buf[:]); true {
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case nr < 0:
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fmt.Fprintf(os.Stderr, "cat: error reading: %s\n", err.Error())
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os.Exit(1)
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case nr == 0: // EOF
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return
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case nr > 0:
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if nw, ew := os.Stdout.Write(buf[0:nr]); nw != nr {
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fmt.Fprintf(os.Stderr, "cat: error writing: %s\n", ew.Error())
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}
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}
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}
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}
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func main() {
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flag.Parse() // Scans the arg list and sets up flags
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if flag.NArg() == 0 {
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cat(os.Stdin)
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}
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for i := 0; i < flag.NArg(); i++ {
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f, err := os.Open(flag.Arg(i))
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if f == nil {
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fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err)
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os.Exit(1)
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}
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cat(f)
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f.Close()
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}
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}
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