Derived external process

dateCmd := exec.Command("date")
dateOut, err := dateCmd.Output()
if err != nil {
    
	panic(err)
}
fmt.Println("> date")
fmt.Println(string(dateOut))

> date
2022 year 4 month 20 Japan Wednesday 19 when 16 branch 44 second CST

exec.Command The results of the implementation of , Consistent with the results executed on the command line .

grepCmd := exec.Command("grep", "hello")
grepIn, _ := grepCmd.StdinPipe()
grepOut, _ := grepCmd.StdoutPipe()
grepCmd.Start()
grepIn.Write([]byte("hello grep\ngoodbye grep"))
grepIn.Close()
grepBytes, _ := io.ReadAll(grepOut)
grepCmd.Wait()
fmt.Println("> grep hello")
fmt.Println(string(grepBytes))

> grep hello
hello grep

Different from the above code , Here, the input is explicitly obtained / Output pipe , Start the process , Enter data into the pipeline , Read pipeline output , Finally, wait for the process to end .

lsCmd := exec.Command("bash", "-c", "ls -a -l -h")
lsOut, err := lsCmd.Output()
if err != nil {
    
	panic(err)
}
fmt.Println("> ls -a -l -h")
fmt.Println(string(lsOut))

> ls -a -l -h
total 3992
drwxr-xr-x 4 baiye staff 128B 4 20 19:16 .
drwxr-xr-x 83 baiye staff 2.6K 4 2 10:38 …
-rwxr-xr-x 1 baiye staff 1.9M 4 20 19:16 spawning-processes
-rw-r–r-- 1 baiye staff 703B 3 28 18:11 spawning-processes.go

When generating commands , An array of commands and parameters that need to be explicitly described , You can't just pass in a command line string . If you need to execute the full command of string style , have access to bash -c Options .

Replace current process

binary, lookErr := exec.LookPath("ls")
if lookErr != nil {
    
	panic(lookErr)
}
args := []string{
    "ls", "-a", "-l", "-h"}
env := os.Environ()
execErr := syscall.Exec(binary, args, env)
if execErr != nil {
    
	panic(execErr)
}

total 3016
drwxr-xr-x 4 baiye staff 128B 4 20 20:20 .
drwxr-xr-x 83 baiye staff 2.6K 4 2 10:38 …
-rwxr-xr-x 1 baiye staff 1.5M 4 20 20:20 execing-processes
-rw-r–r-- 1 baiye staff 300B 3 28 18:53 execing-processes.go