how to get PID's of linux commands executed through python modules?

[buran]

i am not able to read this output through subprocess.Popen, os.popen and commands.getstatusoutput. commands give error as "syntax error near unexpected token '&' and others give empty string as output and command is running the background successfully though.

Maybe show your code...

subprocess.Popen gives a pid but when killed or terminated i could still see the tail and egrep pid's staying alive.

Do you pass shell=True? in which case as docs state:

Note that if you set the shell argument to True, this is the process ID of the spawned shell.