Check if second script is running or already finished

Question

I need to check if a scriptA.py is still running, in scriptB.py . Both are started individually, but scriptB.py may only continue if scriptA.py is still running.

I know I could use

import subprocess

process = subprocess.Popen(['pgrep', 'scriptA.py'], stdout=subprocess.PIPE)

process.wait()

if not process.returncode:
    print "Process running"
else:
    print "Process not running"

But script a runs in a tmux session. Which is called like tmux new -d -s scriptA_2014-12-09-10-54-02-697559 'cd /home/user/scriptA; python scriptA.py -flag; echo $? > /tmp/scriptA_2014-12-09-10-54-02-697559' tmux new -d -s scriptA_2014-12-09-10-54-02-697559 'cd /home/user/scriptA; python scriptA.py -flag; echo $? > /tmp/scriptA_2014-12-09-10-54-02-697559'

If i pgrep scriptA.py it doesn't return the PID . pgrep tmux would work, but that there might be other tmux sessions, so I can't use that.

I could do something like ps aux | grep scriptA.py | wc -l ps aux | grep scriptA.py | wc -l ps aux | grep scriptA.py | wc -l and check the line count - but this feels like it's very variable.

How else could I verify if scriptA.py is running?

Answer 1

I'm now using the PID , written to a file at script execution.. The code I use seems to work for my case:

In scriptA , at execution start:

pidf = open("./scriptA_pid.tmp","w")
pidf.write(str(os.getpid()))
pidf.close()

In scriptB , at the beginning of the loop that needs to be executed until scriptA is done.

with open("./scriptA_pid.tmp","r") as f:
    scriptA_pid = f.read()
chk_sA = subprocess.Popen(['kill -0 '+str(scriptA_pid)+' > /dev/null 2>&1; echo $?'],stdout=subprocess.PIPE,stderr=devnull,shell=True)
chk_sA.wait()
sA_status = chk_sA.stdout.read()

if int(sA_status) == 0:
    #ScriptA is still running
    pass
else:
    #ScriptA is not running
    sys.exit(0)