Autokey - Focus App Window If Running, Launch App If Not

Question

I'm trying to obtain the processID of pcmanfm like this:

pgrep -f "pcmanfm"

When pcmanfm is not running, the command above returns nothing (as I expect).

However, when I run the command from python, it returns a process ID even when pcmanfm is not running:

processID = os.system('pgrep -f "pcmanfm"')

Furthermore, if you run the command above multiple times at a python3 prompt, it returns a different processID each time. All the while, pcmanfm has been closed prior to these commands.

>>> processID = os.system('pgrep -f "pcmanfm"')
17412
>>> processID = os.system('pgrep -f "pcmanfm"')
17414
>>> processID = os.system('pgrep -f "pcmanfm"')
17416

This is really messing up my ability to launch pcmanfm if it isn't currently running. My script thinks it is running when it isn't.

Why is this happening?

I'm actually encountering this issue in an Autokey script that I've attempted to write based on this video I watched. Here's my current script:

processID = system.exec_command('pgrep -f "pcmanfm" | head -1',True)
dialog.info_dialog("info",processID)

if (processID):
    cmd = "wmctrl -lp | grep " + processID + " | awk '{print $1}'"
    windowID = system.exec_command(cmd,True)
    # dialog.info_dialog("info",windowID)
    cmd = "wmctrl -iR " + windowID
    #dialog.info_dialog("info",cmd)
    system.exec_command(cmd,False)
else:
    #os.system("pcmanfm /home/user/Downloads")
    cmd = "/usr/bin/pcmanfm /home/user/Downloads"
    system.exec_command(cmd,False)

The problem is, I keep getting processIDs even when pcmanfm isn't running. The script properly focuses pcmanfm if it is running, but it won't launch it if it isn't.

Update: I finally got this script to work by taking out -f and replacing it with -nx (from @they 's advice). Also, I added some exception handling to ignore autokey exceptions caused by empty output that's expected. Additionally, I converted it to a (more flexible) function so that it will service a wider variety of commands/applications:

import re
def focusOrLaunch(launchCommand):
    appName = re.findall('[^\s/]+(?=\s|$)',launchCommand)[0]
    processID = None
    try:
        processID = system.exec_command('pgrep -nx "' + appName + '"',True)
    except Exception as e:
        #dialog.info_dialog("ERROR",str(e))
        pass

    #dialog.info_dialog("info",processID)
    if (processID):
        cmd = "wmctrl -lp | grep " + processID + " | awk '{print $1}'"
        windowID = system.exec_command(cmd,True)
        # dialog.info_dialog("info",windowID)
        cmd = "wmctrl -iR " + windowID
        #dialog.info_dialog("info",cmd)
        system.exec_command(cmd,False)
    else:
        system.exec_command(launchCommand,False)
    
cmd = "/usr/bin/pcmanfm ~/Downloads"
focusOrLaunch(cmd)

Answer 1

Proposed solution:

Remove the -f option from your pgrep command.

---

Explanation:

You probably get the process ID of the shell that is executed to run your command. A new shell process with a new PID will be created for every system.exec_command.

Run e.g. sh -c 'pgrep -af nonexistent' and check the output. You will probably get something like

11300 sh -c pgrep -af nonexistent

With an existing command I also get a line for the shell

sh -c 'pgrep -af sshd'
695 /usr/sbin/sshd -D
11207 sshd: pi [priv]
11224 sshd: pi@pts/0
11331 sshd: [accepted]
11343 sh -c pgrep -af sshd

Depending on the PID values, your head command might extract the PID of a process you are looking for or the PID of the shell process.

With option -f you explicitly tell pgrep to search the whole command line instead of the process name only. This way it will find the string in the shell's command line argument.

Without -f you won't get the shell process.

$ sh -c 'pgrep -a sshd'
695 /usr/sbin/sshd -D
11207 sshd: pi [priv]
11224 sshd: pi@pts/0
11364 sshd: [accepted]

Answer 2

Here's my take on focusing a program's window if it's running or launching the program if it's not. I used Firefox in the example, but I'm hoping it would work the same way for your pcmanfm if you made the appropriate edits to remove Firefox from the example code and replace it with the equivalent PCManFM information.

Note that I used the subprocess.Popen function because it allows you to execute other code and/or interact with the process with the subprocess.communicate function while the process is running. If that isn't needed, you can use the subprocess.run function instead.

output = system.exec_command("wmctrl -l", getOutput=True)
if "Firefox" in output:
    window.activate("Firefox",switchDesktop=True)
else:
    subprocess.Popen(["firefox"])