get process id through Perl script

Question

In my script, I am executing cat, then trying to grep to get the process id.

I used this :

ps | grep -e \'cat$\' | cut -d\' \' -f2 | head -n 1

but it's not returning anything.

Answer 1

When you start a background process in a shell with program & you can access the PID of the child process through $!.

For example:

bash-4.2.37$ cat &
[1] 9664
bash-4.2.37$ CAT_PID=$!
...time passes...
bash-4.2.37$ echo $CAT_PID
9664