# 启动外部命令和程序

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。

这个函数返回被启动进程的 id（pid），或者启动失败返回错误。

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：

示例 13.6 [exec.go](https://github.com/yangchuansheng/the-way-to-go_ZH_CN/tree/f30ab7d8c58f85840a0afb548024b93642b518d5/eBook/examples/chapter_13/exec.go)：

```go
// exec.go
package main
import (
    "fmt"
    "os/exec"
    "os"
)

func main() {
// 1) os.StartProcess //
/*********************/
/* Linux: */
env := os.Environ()
procAttr := &os.ProcAttr{
            Env: env,
            Files: []*os.File{
                os.Stdin,
                os.Stdout,
                os.Stderr,
            },
        }
// 1st example: list files
pid, err := os.StartProcess("/bin/ls", []string{"ls", "-l"}, procAttr)  
if err != nil {
        fmt.Printf("Error %v starting process!", err)  //
        os.Exit(1)
}
fmt.Printf("The process id is %v", pid)
```

输出：

```go
The process id is &{2054 0}total 2056
-rwxr-xr-x 1 ivo ivo 1157555 2011-07-04 16:48 Mieken_exec
-rw-r--r-- 1 ivo ivo    2124 2011-07-04 16:48 Mieken_exec.go
-rw-r--r-- 1 ivo ivo   18528 2011-07-04 16:48 Mieken_exec_go_.6
-rwxr-xr-x 1 ivo ivo  913920 2011-06-03 16:13 panic.exe
-rw-r--r-- 1 ivo ivo     180 2011-04-11 20:39 panic.go
```

```go
// 2nd example: show all processes
pid, err = os.StartProcess("/bin/ps", []string{"-e", "-opid,ppid,comm"}, procAttr)  

if err != nil {
        fmt.Printf("Error %v starting process!", err)  //
        os.Exit(1)
}

fmt.Printf("The process id is %v", pid)
```

```go
// 2) exec.Run //
/***************/
// Linux:  OK, but not for ls ?
// cmd := exec.Command("ls", "-l")  // no error, but doesn't show anything ?
// cmd := exec.Command("ls")          // no error, but doesn't show anything ?
    cmd := exec.Command("gedit")  // this opens a gedit-window
    err = cmd.Run()
    if err != nil {
        fmt.Printf("Error %v executing command!", err)
        os.Exit(1)
    }
    fmt.Printf("The command is %v", cmd)
// The command is &{/bin/ls [ls -l] []  <nil> <nil> <nil> 0xf840000210 <nil> true [0xf84000ea50 0xf84000e9f0 0xf84000e9c0] [0xf84000ea50 0xf84000e9f0 0xf84000e9c0] [] [] 0xf8400128c0}
}
// in Windows: uitvoering: Error fork/exec /bin/ls: The system cannot find the path specified. starting process!
```

## 链接

* [目录](https://github.com/yangchuansheng/the-way-to-go_ZH_CN/tree/f30ab7d8c58f85840a0afb548024b93642b518d5/eBook/directory.md)
* 上一节：[一种用闭包处理错误的模式](/the-way-to-go-zh-cn/di-san-bu-fen-go-gao-ji-bian-cheng/13.0/13.5.md)
* 下一节：[Go 中的单元测试和基准测试](/the-way-to-go-zh-cn/di-san-bu-fen-go-gao-ji-bian-cheng/13.0/13.7.md)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://ryanyang.gitbook.io/the-way-to-go-zh-cn/di-san-bu-fen-go-gao-ji-bian-cheng/13.0/13.6.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.