check whether a process is still running on remote hosts

[tina_zy_qian at yahoo.com]

I newly learned Python, and I need to wrap up a script to do following.

Env:
1: One launcher Linux VM (from where to run the Python script)
2. 100+ Linux VM

requirement:
In general, run a remote_script on remote 100 VMs and get the log files generated to remote hosts back to launcher.

steps
1. cp (pexpect.spawn('scp  ')) supporting files including the remote_script to remotehost:/remote_folder
2. run remote_script on remote host  ( pexpect.spawn('ssh %s@%s "%s"' % (user,host,cmd))
3. wait and check until the remote_script was run on remote host. (to check "ps -ef" result on remote hosts)
4. collect data from remote hosts -- reverse to step 1. 


I briefly implemented other steps expect step 3. Two options are below. 

option 1: run another script "ps -ef|grep remote_script and output result to a local file, then collected the files to launcher.

option 2: run pexect.spawn('ssh' ....'ps -e') to get the result directly to laucher console.
But how I can get only the output for "ps -ef" command only?

I must use the (users, passwords, and hosts) way to do ssh and scp because I may not be allowed to use ssh key on some hosts. Any suggestions or sample code for step 3 or the whole script are appreciated. Thanks.