Process ID

Timok · 10-04-2005, 09:05 AM

Hello,

I would like to do something like that in a shell script

MyProcessA &
MyProcessB &
MyProcessC &
echo "My processes started"
wait MyProcessA
wait MyProcessB
wait MyProcessC
echo "My processes finished"

The wait command can receive a PID and wait for its completion. But I do not know how to get the PID of MyProcessA when I start it. I do not want to use the ps command because MyProcessA may be finished then. All I want is the PID that you have when you type "MyProcessA &". Ex:

/users/timok/tests/shell>mkdir toto &
[1] 1058

So I would like to get the value '1058' in a variable.

Thanks for any help,
Timok

kjordan · 10-04-2005, 10:11 AM

$! will give the pid of the most recently executed background process in your script. So just get the pid of it after you execute it and put it in a variable.

druuna · 10-04-2005, 10:15 AM

Hi,

Use $!

Code:

#!/bin/bash

ls -l >/dev/null &
echo "\$! : $!"

ls -l >/dev/null &
echo "\$! : $!"

ls -l >/dev/null &
echo "\$! : $!"

Hope this helps.

Timok · 10-04-2005, 11:54 AM

Thank you both for this quick reply. It works just like I wanted.

Timok