Killing multiple processes at once in Linux

Requirement 1:  Kill all the running processes owned by a particular user.

List all the Process IDs of user

# pgrep -u <username>         

Find Real UID of user
# id <username>

Kill all the processes owned by user with Real UID specified.
# pkill -U <Real UID>           

Example:

Killing all the processes owned by userid 'nagios'

# pgrep -u nagios

# id nagios 

   uid=510(nagios) gid=510(nagios) groups=510(nagios)

# pkill –U 510

Requirement 2:  Kill all processes that are running with some process-name or string (from ps output)

Using "For" loop:

[root@hostxyz ~]# for i in `ps -ef | grep -v grep | grep [username/some string] | awk '{print $2}'`; do kill -9 $i; echo “process id $i is killed”; done

Using "Xargs":
[root@hostxyz ~]# ps aux | grep -v grep | grep [username/some string] | awk '{print $2}' | xargs kill -9

Sample execution:  

To kill all processes that has string "jboss" in it 

[root@hostxyz ~]# for i in `ps -ef | grep -v grep | grep jboss | awk '{print $2}'`; do kill -9 $i; echo "Process id $i is killed"; done

[root@hostxyz ~]# ps aux | grep -v grep | grep jboss | awk '{print $2} | xargs kill -9