代码：

package main

import "io"
import "os"
import "fmt"
import "crypto/md5"
import "crypto/sha1"

func main() {
    if (len(os.Args) < 3) {
        fmt.Printf("usage: check [md5|sha1] file\n\n")
        fmt.Printf("  %4s: %s\n", "md5", "计算文件md5值")
        fmt.Printf("  %4s: %s\n", "sha1", "计算文件sha1值")
        return
    }
    f, err := os.Open(os.Args[2])
    if err != nil {
        fmt.Printf("Sorry, file open failed\n")
        return
    }
    buf := make([]byte, 1024 * 1024 * 16 * 16)
    switch os.Args[1] {
        case "md5":
            h := md5.New()
            for {
                n, err := f.Read(buf)
                h.Write(buf[:n])
                if err == io.EOF {
                    break
                }
            }
            fmt.Printf("%x\n", h.Sum(nil))
        case "sha1":
            h := sha1.New()
            for {
                n, err := f.Read(buf)
                h.Write(buf[:n])
                if err == io.EOF {
                    break
                }
            }
            fmt.Printf("%x\n", h.Sum(nil))
        default :
            fmt.Printf("参数有误\n")
    }
}

编译运行：

run.jpg