Golang Linux Shell Programming (i)

1. Invoking system commands

The Exec package executes the external command, which will be OS. The startprocess is packaged to make it easier to map to stdin and stdout and to connect I/O with pipe

funcstring, arg ...string) *Cmd {}

Call system command:

package mainimport (   "os/exec"   "log"   "fmt")func main() {   cmd := exec.Command("ls","-l")   out,err := cmd.CombinedOutput()//标准输出 标准错误 组合   //out, err := cmd.Output()   //Output()和CombinedOutput()不能够同时使用，   // 因为command的标准输出只能有一个，同时使用的话便会定义了两个，便会报错   ifnil {      log.Fatal(err)   }   fmt.Println(string(out))}

2. Interactive Invoke system commands

 PackageMainImport("Os/exec"   "Bufio"   "FMT"   "Log"   "Time")funcMain () {cmd: = Exec.command ("ls","-L") Out,_: =cmd. Stdoutpipe ()//stdoutpipe Returns a piping pipe that is connected to the command standard output   ifERR: = cmd. Start (); Err! =Nil{log. Fatal ("Start Error:%v", err)} f: = Bufio. Newreader (out) for{line,err: = f.readstring (' \ n ')ifErr! =Nil{ Break} FMT. Print (line)} time. Sleep (time. Hour)//cmd. Wait ()   //wait wait for command to exit, he must use with start,   //If the command executes smoothly and exits successfully, nil is returned, otherwise the error is returned, where wait is the release of all the resources associated with the cmd command}

No Wait () will spawn zombie process, 3466 defunct zombie process, wait for corpse

go build cmd.go./cmd[[email protected] ]#ps -ef |grep cmd2root       3466   2539  0 20:37 pts/0    00:00:00 ./cmd2[[email protected] ]#ps -ef |grep lsroot        683      1  0 18:43 ?        00:00:21 /usr/bin/vmtoolsdroot       3470   3466  0 20:37 pts/0    00:00:00 [ls] <defunct>

3. Homemade Bash

 PackageMainImport("Bufio"   "FMT"   "OS"   "Os/exec"   "Strings")funcMain () {host, _: = OS. Hostname () Prompt: = Fmt. Sprintf ([[Email protected]%s]$], host) R: = Bufio. Newscanner (OS. Stdin)//r: = Bufio. Newreader (OS. Stdin)    for{FMT. Print (Prompt)if!r.scan () { Break} Line: = R.text ()//Line, _: = r.readstring (' \ n ')      //Line = strings. Trimspace (line)      if Len(line) = =0{Continue} args: = Strings. Fields (line) cmd: = Exec.command (args[0], args[1:]...) Cmd. Stdin = OS. Stdin cmd. Stdout = OS. Stdout cmd. Stderr = OS. Stderr err: = cmd. Run ()ifErr! =Nil{FMT. PRINTLN (Err)}}}

4. Piping pipe

 PackageMainImport("FMT"   "IO"   "Log"   "OS"   "Os/exec"   "Strings")funcMain () {line: ="ls | grep F "Cmds: = Strings. Split (Line,"|") S1: = Strings. Fields (cmds[0]) S2: = Strings. Fields (cmds[1]) FMT. Println (S1) fmt. PRINTLN (S2) r, W: = Io. Pipe () Cmd1: = Exec.command (s1[0], s1[1:]...) CMD2: = Exec.command (s2[0], s2[1:]...)//cmd1: = Exec.command ("ls")   //CMD2: = Exec.command ("grep", "F")Cmd1. Stdin = OS. Stdin cmd1. Stdout = w cmd2. Stdin = R cmd2. Stdout = OS. Stdout cmd1. Start () cmd2. Start () log. Print ("Start") cmd1. Wait () cmd2. Wait ()}

5.shell.go

Https://github.com/ningxin1718/gosubshell

Golang Linux Shell Programming (i)