providing input with subprocess module

Question

I am trying to lock screen in the ubuntu server using "gnome-screensaver-command" and then unlock it by pressing enter key. This is working fine when I am doing it manually and hence thought of automating the same with Python Subprocess module.

The problem I am facing is it is locking the screen and after the timer expiry the enter key("echo -ne \n", got to know this can be used to send enter through CLI) is not happening.

Below is the code snippet.

import subprocess
import time


cmd = subprocess.call(["/usr/bin/gnome-screensaver-command", "-l"])
time.sleep(10)
subprocess.call(["echo", "-ne", "\n"])

Tried another way of doing it:

#******THIS METHOD IS NOT LOCKING THE SCREEN AT ALL*******

cmd = subprocess.Popen(["/usr/bin/gnome-screensaver-command", "-l"], stdin = subprocess.PIPE, shell=True)
time.sleep(10)
cmd.communicate(input="\n")

What should be done to work it as per my requirement ?

score 0 · Answer 1 · answered Jun 15 '17 at 11:31

0

the problem is that the screensaver reads the keyboard but not through the process standard input.

Something that (maybe) would work would be to send a keyboard event to the desktop. There are programs (like caffeine on Windows) which do that to prevent the screensaver from activating, but let me propose a portable alternative which doesn't involve keyboard events:

run the process
wait 10 seconds
kill the screensaver process

like this:

import subprocess
import time


cmd = subprocess.Popen(["/usr/bin/gnome-screensaver-command", "-l"])
time.sleep(10)
cmd.terminate()

answered Jun 15 '17 at 11:31

Jean-François Fabre

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the process is not getting killed with terminate, as you have suggested. – Here_2_learn Jun 15 '17 at 11:47
arg... annoying. Does the script end or stays stuck? – Jean-François Fabre Jun 15 '17 at 11:51
try to replace `cmd.terminate()` by `os.kill(cmd.pid)`. But I have little hope. – Jean-François Fabre Jun 15 '17 at 16:10
1

true: `os.kill(pid, signal.SIGKILL)` then. https://stackoverflow.com/questions/6549669/how-to-kill-process-and-child-processes-from-python – Jean-François Fabre Jun 15 '17 at 16:20
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/146783/discussion-between-here-2-learn-and-jean-francois-fabre). – Here_2_learn Jun 15 '17 at 16:25

providing input with subprocess module

1 Answers1