/
main.go
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/
main.go
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package main
import (
"fmt"
"io/ioutil"
"log"
"os"
)
func cp(srcName, dstName string) error {
src, err := os.Open(srcName)
if err != nil {
return fmt.Errorf("my program broke opening: %v", err)
}
defer src.Close()
dst, err := os.Create(dstName)
if err != nil {
return fmt.Errorf("my program broke creating:%v ", err)
}
defer dst.Close()
bs, err := ioutil.ReadAll(src)
if err != nil {
return fmt.Errorf("my program broke reading: %v", err)
}
_, err = dst.Write(bs)
if err != nil {
return fmt.Errorf("my program broke writing: %v", err)
}
return nil
}
func main() {
if len(os.Args) < 3 {
log.Fatalln("Usage: 03 <SRC> <DST>")
}
srcName := os.Args[1]
dstName := os.Args[2]
err := cp(srcName, dstName)
if err != nil {
log.Fatalln(err)
}
}
// THE PROBLEM WITH THIS PROGRAM:
// it reads the entire file into memory
// not good if you're copying a multi-gigabyte file
/*
step 1 - at command line enter:
go install
step 2 - at command line enter:
03 initial.txt second.txt
*/