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88 lines
2.8 KiB
Markdown
88 lines
2.8 KiB
Markdown
# 13.6 启动外部命令和程序
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`os` 包有一个 `StartProcess` 函数可以调用或启动外部系统命令和二进制可执行文件；它的第一个参数是要运行的进程，第二个参数用来传递选项或参数，第三个参数是含有系统环境基本信息的结构体。
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这个函数返回被启动进程的 id (pid)，或者启动失败返回错误。
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`exec` 包中也有同样功能的更简单的结构体和函数；主要是 `exec.Command(name string, arg ...string)` 和 `Run()`。首先需要用系统命令或可执行文件的名字创建一个 `Command` 对象，然后用这个对象作为接收者调用 `Run()`。下面的程序（因为是执行 Linux 命令，只能在 Linux 下面运行）演示了它们的使用：
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示例 13.6 [exec.go](examples/chapter_13/exec.go)：
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```go
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// exec.go
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package main
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import (
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"fmt"
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"os/exec"
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"os"
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)
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func main() {
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// 1) os.StartProcess //
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/*********************/
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/* Linux: */
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env := os.Environ()
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procAttr := &os.ProcAttr{
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Env: env,
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Files: []*os.File{
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os.Stdin,
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os.Stdout,
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os.Stderr,
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},
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}
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// 1st example: list files
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pid, err := os.StartProcess("/bin/ls", []string{"ls", "-l"}, procAttr)
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if err != nil {
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fmt.Printf("Error %v starting process!", err) //
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os.Exit(1)
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}
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fmt.Printf("The process id is %v", pid)
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```
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输出：
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``` go
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The process id is &{2054 0}total 2056
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-rwxr-xr-x 1 ivo ivo 1157555 2011-07-04 16:48 Mieken_exec
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-rw-r--r-- 1 ivo ivo 2124 2011-07-04 16:48 Mieken_exec.go
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-rw-r--r-- 1 ivo ivo 18528 2011-07-04 16:48 Mieken_exec_go_.6
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-rwxr-xr-x 1 ivo ivo 913920 2011-06-03 16:13 panic.exe
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-rw-r--r-- 1 ivo ivo 180 2011-04-11 20:39 panic.go
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```
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```go
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// 2nd example: show all processes
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pid, err = os.StartProcess("/bin/ps", []string{"ps", "-e", "-opid,ppid,comm"}, procAttr)
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if err != nil {
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fmt.Printf("Error %v starting process!", err) //
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os.Exit(1)
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}
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fmt.Printf("The process id is %v", pid)
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```
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```go
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// 2) exec.Run //
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/***************/
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// Linux: OK, but not for ls ?
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// cmd := exec.Command("ls", "-l") // no error, but doesn't show anything ?
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// cmd := exec.Command("ls") // no error, but doesn't show anything ?
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cmd := exec.Command("gedit") // this opens a gedit-window
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err = cmd.Run()
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if err != nil {
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fmt.Printf("Error %v executing command!", err)
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os.Exit(1)
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}
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fmt.Printf("The command is %v", cmd)
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// The command is &{/bin/ls [ls -l] [] <nil> <nil> <nil> 0xf840000210 <nil> true [0xf84000ea50 0xf84000e9f0 0xf84000e9c0] [0xf84000ea50 0xf84000e9f0 0xf84000e9c0] [] [] 0xf8400128c0}
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}
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// in Windows: uitvoering: Error fork/exec /bin/ls: The system cannot find the path specified. starting process!
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```
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## 链接
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- [目录](directory.md)
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- 上一节：[一种用闭包处理错误的模式](13.5.md)
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- 下一节：[Go 中的单元测试和基准测试](13.7.md)
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