CODEWITHSUNDEEP
linuxbashredhat
aviad
aviad

Reputation: 8278

pkill kills sshd process started by other user in parent shell

I have a script that runs from a newly created shell. OS is Red Hat Enterprise Linux Server release 5.4 (Tikanga). In certain point when the script detects that some application (started by the script) is hanging the script tries to terminate all the procesess it started. I assumed that the correct command for terminating all processes started by current user in current shell is: 

pkill /?

The problem is that it kills sshd that is started in parent shell (by init.d) and the putty console disconnects showing error message.

I wonder:

  1. How is it possible for specific user in specific shell to terminate process started by other user in parent shell?
  2. What would be correct command to terminate all processes started by the script currently running?

I have found some solution where i store all the PIDs and when the script needs to terminate them I run in the loop the following:

[ws@RHDev ~]# pkill $(ps aux | grep $pid | awk '{print $2}')

However, I am looking for one-liner that simply terminates all the processes started by the current script.

Upvotes: 0

Views: 2724

Answers (2)

Maxim Egorushkin
Maxim Egorushkin

Reputation: 136256

I assumed that the correct command for terminating all processes started by current user in current shell is:

pkill /?

This command matches every single process in the system because it effectively requires only 0 symbols from process name to match. pgrep -l /? demonstrates that.

How is it possible for specific user in specific shell to terminate process started by other user in parent shell?

From man kill(2):

   For  a  process  to  have permission to send a signal it must either be
   privileged (under Linux: have the CAP_KILL capability), or the real  or
   effective  user  ID of the sending process must equal the real or saved
   set-user-ID of the target process.  In the case of SIGCONT it  suffices
   when the sending and receiving processes belong to the same session.

Do you invoke pkill from user root?

What would be correct command to terminate all processes started by the script currently running?

When bash starts it creates its own process group. Child processes it creates are put in the same process group. Hence:

kill -- -$$

Kills all processes started by the current script. Provided that those processes didn't become group leaders.

Upvotes: 1

core1024
core1024

Reputation: 1882

You can filter subprocesses by the current process pid. The ps command can do this using the --ppid parameter.

ps opid --ppid=7051 | tail -n +2 | xargs kill

here tail -n +2 is to strip the ps headers.

Upvotes: 1

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