Golang processes: Difference between revisions
From wikinotes
Line 61: | Line 61: | ||
stdout, err := cmd.Output() | stdout, err := cmd.Output() | ||
// must be read-from/written-to in go routine! (can be anonymous) | |||
// ex. go func() { defer stdin.Close(); stdin.Write([]byte("foo")); }() | |||
reader, err := cmd.StderrPipe() | reader, err := cmd.StderrPipe() | ||
reader, err := cmd.StdoutPipe() | reader, err := cmd.StdoutPipe() |
Revision as of 13:22, 1 July 2022
Start/Manage a process, or get information about system processes.
Documentation
os
https://pkg.go.dev/os@go1.18.3
Current Process
import "os" import "os/user" os.Executable() os.Getpid() os.Getppid() os.Getuid() os.Getgid() os.Exit(1) // exit process with exitcode '1' // environment envvars := os.Environ() // ["FOO=bar", "BAR=baz", ...] pwd, err := os.Getwd() // get current pwd/cwd user.Current() // 'will'
Manage Processes
import "syscall" import "os" import "os/signal" proc := os.Process.FindProcess(1234) // find process with pid proc.Kill() // kill process (-9/SIGKILL) proc.Signal(os.Iterrupt) // send SIGINT to process (looks like you can use any syscall.SIG*) proc.Wait() // wait for process to end syscall.Kill(1234, syscall.SIGINT) // send SIGINT to pid 1234
Subprocess
high-level/friendly
// 1. create command, // 2. modify it's exec.Cmd struct (ex. stdin,stdout) // 3. run process // 4. cmd.ProcessState has info about process, including exitcode import "os" import "os/exec" cmd := exec.Command("netstat", "-an") stdout, err := cmd.Output() // must be read-from/written-to in go routine! (can be anonymous) // ex. go func() { defer stdin.Close(); stdin.Write([]byte("foo")); }() reader, err := cmd.StderrPipe() reader, err := cmd.StdoutPipe() writer, err := cmd.StdinPipe() cmd.Process.Pid // get pid (after starting process) err := cmd.Run() // run and wait err := cmd.Start() // run, don't wait err := cmd.Wait() // wait for proces to finishlow-level
// 1. create ProcAttr // 2. start process // 3. wait for process // 4. get info from it's ProcessState import "os" import "os/exec" psAttr := os.ProcAttr{ Dir: "/var/tmp", Env: []string{"FOO=BAR"}, } ps := os.StartProcess("netstat", []string{"-a", "-n"}, psAttr) pstate, err := ps.Wait() pstate.ExitCode()
Reading from STDIN
stat, _ := os.Stdin.Stat() if (stat.Mode() & os.ModeNamedPipe) == 0 { fmt.Println("Nothing to read on stdin") os.Exit(1) } else { var reader = bufio.NewReader(os.Stdin) for { line, err := reader.ReadString('\n') if err == io.EOF { break } fmt.Print(line) time.Sleep(1 * time.Second) } }