package main

import (
	"fmt"
	"os/exec"
)

/*
  To see the PID, command, and current working directory for all processes, you can run:

   1 ps -eo pid,cmd,cwd

  Explanation

   * -e: Selects every process on the system.
   * -o pid,cmd,cwd: Specifies a user-defined format.
       * pid: Shows the Process ID.
       * cmd: Shows the command with its arguments.
       * cwd: Shows the current working directory of the process.

  Alternative for a Specific Process (Linux)

  If you already know the PID and just want to find its working directory, there are two even more direct methods on Linux:

   1. Using the `pwdx` command:
   1     pwdx <PID>
      This will print only the CWD for that specific process.

   2. Checking the `/proc` filesystem:
      The CWD is exposed as a symbolic link. You can read it with ls or readlink:

   1     ls -l /proc/<PID>/cwd
      This will show you where the cwd link points.
*/

func main() {
	fmt.Println("Starting a 'sleep 15' command...")

	// 1. Create the command.
	cmd := exec.Command("sleep", "15")

	// 2. Start the command. This is non-blocking.
	err := cmd.Start()
	if err != nil {
		fmt.Printf("Error starting command: %v\n", err)
		return
	}

	// 3. If Start() succeeded, the PID is now available.
	// The check for err != nil above is critical to prevent a panic
	// from a nil pointer dereference on cmd.Process.
	pid := cmd.Process.Pid
	fmt.Printf("--> Successfully started process with PID: %d\n", pid)
	fmt.Println("--> You can verify this with 'ps aux | grep", pid, "'")

	fmt.Println("Waiting for the process to finish in the background...")

	// 4. Wait for the command to complete and release its resources.
	err = cmd.Wait()
	if err != nil {
		fmt.Printf("Command finished with error: %v\n", err)
	} else {
		fmt.Println("Command finished successfully.")
	}
}