Running a linux command from python

I usually use subprocess for running an external command. For your case, you can do something like the following

from subprocess import Popen, PIPE

p = Popen('ps -ef | grep rtptransmit | grep -v grep', shell=True,
          stdout=PIPE, stderr=PIPE)
out, err = p.communicate()

The output will be in out variable.

commands is deprecated, you should not use it. Use subprocess instead

import subprocess
a = subprocess.check_output('ps -ef | grep rtptransmit | grep -v grep', shell=True)

ps apparently limits its output to fit into the presumed width of the terminal. You can override this width with the $COLUMNS environment variable or with the --columns option to ps.

The commands module is deprecated. Use subprocess to get the output of ps -ef and filter the output in Python. Do not use shell=True as suggested by other answers, it is simply superfluous in this case:

ps = subprocess.Popen(['ps', '-ef', '--columns', '1000'], stdout=subprocess.PIPE)
output = ps.communicate()[0]
for line in output.splitlines():
    if 'rtptransmit' in line:
        print(line)

You may also want to take a look the pgrep command by which you can directly search for specific processes.