find all ocurrences for a command (in this case python) :

awk '{for(i = 11; i <= NF; i++) printf $i " "; printf "n"}' < <(ps aux | grep python)

kill all ocurrences for a command (python again) :

ps aux | grep python | awk {'print "kill " $2'} | bash

also can be added the -9 signal

ps aux | grep python | awk {'print "kill -9 " $2'} | bash

If you need a process to survive your logging out of the system (or being knocked off of it), you can either screen it or wrap it with nohup. If you nohup, you'll lose control of it entirely, but the output will be written to nohup.out. With screen you can re-attach and take control later:

# nohup program -opts args &

-or-

# screen (press 'ctrl+a d' to detach after you've run the proc)

Ever been on a machine that was ailing and just wouldn't respond? As soon as you're root, lower the priority of the offending process ID(s) (in this example, 1103) by using the 'renice' command:

# renice -19 1103

If you need to find the process hogging your CPU, try this:

$ ps aux | awk '!/root|nobody/ { if ($4>2) {print $2}}'

You can use the lsof (LiSt Open Files) utility to view information about which processes own file handles on a system. Since sockets map to file descriptors, lsof will show you which processes own socket connections. If you see that your machine is connected to another on TCP port 6234 (source or dest) and you want to find out which process(es) are responsible for the connection, run:

# lsof -ni tcp:6234

Note that when run as an unprivileged user, lsof will only show you file descriptors that you have permission to see. You must run lsof as root to see everything in the kernel.

Zsh can run a command and let you do things with a temporary file with the resulting output:

$ emacs -nw =(ps aux)

This will create a temporary file with the output of ps aux and let you edit it in Emacs. Or:

$ diff =(ls) =(ls -F)

Will run diff on the output of the two commands.

If you need to discover on which paths a binary depends, you can sometimes run strings on it and grep for everything starting with a slash:

# strings /usr/sbin/named | grep ^/
/lib/ld-linux.so.2
/etc/named.conf
/etc/rndc.key
/etc/lwresd.conf
/etc/resolv.conf
/var/run/named/named.pid
/var/run/named/lwresd.pid
/dev/null