topic "kill -0" to a process owned by a different user. in Operating System - HP-UX

"kill -0" to a process owned by a different user.

skt_skt — Fri, 19 Mar 2010 10:59:33 GMT

HP-UX 11.11/ PARISC

I have a process [pid] owned by user AAA and I want to access the pid [kill -0 pid ] from another user BBB.

I get a permission denied error when i tried it. Is there a way to get this "process access check" get working by any method??.

I have a custom code which does this stuff and need to get a exit code zero for the program to go further.

Re: "kill -0" to a process owned by a different user.

James R. Ferguson — Fri, 19 Mar 2010 11:07:57 GMT

Hi:

Instead of testing the pid with 'kill -0' I would suggest a simple interrogation with 'ps':

For example, by process name:

# PIDS=$(UNIX95= ps -C myprocess -opid=)

# [ -z "${PIDS}" ] && echo "dead" || echo "alive"

Regards!

...JRF...

Re: "kill -0" to a process owned by a different user.

Horia Chirculescu — Fri, 19 Mar 2010 12:28:31 GMT

Hello,

#-------------------
PID=other_user_pid_no
test=`ps -e | awk '{print $1}' |grep $PID`

if [ "$test" != "$PID" ] ; then echo "We can not test the validity of $PID.";
exit 1;
else
# whatever...
exit 0;
fi
#-------------------

Best regards,
Horia.

Re: "kill -0" to a process owned by a different user.

James R. Ferguson — Fri, 19 Mar 2010 12:42:24 GMT

HI (again):

Too, if you know the pid and don't want to fiddle with the process name, you could do:

# PID=$(UNIX95= ps -p 1234 -opid=)

# [ -z "${PID}" ] && echo "dead" || echo "alive"

Obviously, substitute the actual pid in question for the "1234" value.

Once again, we leverage the UNIX95 behavior of 'ps' to create a custom output of *only* the pid *if* the pid can in fact be found. The '-opid=' says that the output should be the pid and that the normal 'ps' header line should be suppressed.

Regards!

...JRF...

Re: "kill -0" to a process owned by a different user.

skt_skt — Fri, 19 Mar 2010 13:44:45 GMT

I am not lloking for a code modify, rather any other possible changes we could get the same thing working.some unix tricks such as setuid, sticky bit , acl ...

Re: "kill -0" to a process owned by a different user.

James R. Ferguson — Fri, 19 Mar 2010 13:52:49 GMT

Hi (again):

> I am not lloking for a code modify, rather any other possible changes we could get the same thing working.some unix tricks such as setuid, sticky bit , acl

Then create a 'setuid' executable that runs with an effective uid of zero.

Regards!

...JRF...

Re: "kill -0" to a process owned by a different user.

Matti_Kurkela — Fri, 19 Mar 2010 13:58:36 GMT

kill -0 tests if you may send a signal to the target process. If you are not the owner of the process or root, the answer will always be "no".

If you have the PID and just want to know if the process exists or not, you should use the ps command with the -p option. If you want only the information about the existence of the process, throw the ps output away and use only the result code returned by the ps command.

Example:

#!/bin/sh
pid=1 # or whatever

if ps -p $pid >/dev/null; then
echo "process $pid exists"
else
echo "process $pid does not exist"
fi

MK

Re: "kill -0" to a process owned by a different user.

Horia Chirculescu — Mon, 22 Mar 2010 06:15:10 GMT

>Then create a 'setuid' executable that runs with an effective uid of zero.

... or with the uid corresponding to user BBB.

Horia.