Using linux 'screen' command from python

Question

I am running several processes over a cluster. I start every process separately using screen command. It allows me to disconnect from the cluster and when connected view my processes. Starting all the screens one by one is a painful job. I am wondering if we could do it with a python script. The scrip opens the new shell creates the screen runs the process and disconnects. Writes info about all the started processes in a text file like process id starting commands etc.

Secondly, I would like to stop the processes, I would like to put the pid to file and just run a command which will kill all the mentioned processes.

for example

the smaple inut file looks like

   process_name      command
      123            python batch_training.py

I would like to start the screen with the name given in process_name and the commend will be executed in the corresponding frame.

Thanks

Answer 1

Try to use "os.system()" with standart Linux commands. e.g.:

os.system("screen nano")

Answer 2

Can you give the screen object a command in python?

Like:

from os import system

command = 'screen ' + '/dev/ttyUSB0 38400'
result = system(command)

result('ATZ')???

Answer 3

In general, in python, you can run system commands by running

from os import system

and then

system('whatever_shell_command')

So in your case you would type:

from os import system
system('screen')

Unfortunately (this is only sort of related) you can't run more then one command together, so

system('shell_command ', argument)

will not work.

so if you want to do that, you will need to concatenate the two strings:

full_command = 'shell_command ' + argument 
system(full_command)`

Answer 4

If you want to run your command without opening screen session, you should also use -dmS options with screen. So if you want to do that with python, Your code could look like this:

import subprocess

subprocess.call(["screen", "-dmS", "screen_name_1", "top"])
subprocess.call(["screen", "-dmS", "screen_name_2", "top"])
subprocess.call(["screen", "-r"])