How to terminate a python subprocess launched with shell True

Question

I m launching a subprocess with the following command   p   subprocess Popen cmd  stdout subprocess PIPE  shell True    However  when I try to kill using   p terminate     or   p kill     The command keeps running in the background  so I was wondering how can I actually terminate the process    Note that when I run the command with   p   subprocess Popen cmd split    stdout subprocess PIPE    It does terminate successfully when issuing the p terminate

User · Answer

what i feel like we could use   import os import signal import subprocess p   subprocess Popen cmd  stdout subprocess PIPE  shell True   os killpg os getpgid pro pid   signal SIGINT    this will not kill all your task but the process with the p pid

User · Answer

I have not seen this mentioned here  so I am putting it out there in case someone needs it  If all you want to do is to make sure that your subprocess terminates successfully  you could put it in a context manager  For example  I wanted my standard printer to print an out image and using the context manager ensured that the subprocess terminated   import subprocess  with open filename  rb   as f      img f read   with subprocess Popen   usr bin lpr   stdin subprocess PIPE  as lpr      lpr stdin write img  print  Printed image        I believe this method is also cross-platform

User · Answer

I know this is an old question but this may help someone looking for a different method  This is what I use on windows to kill processes that I ve called        si   subprocess STARTUPINFO   si dwFlags    subprocess STARTF USESHOWWINDOW subprocess call   taskkill     IM    robocopy exe     T     F    startupinfo si     IM is the image name  you can also do  PID if you want   T kills the process as well as the child processes   F force terminates it  si  as I have it set  is how you do this without showing a CMD window  This code is used in python 3

User · Answer

If you can use psutil  then this works perfectly   import subprocess  import psutil   def kill proc pid       process   psutil Process proc pid      for proc in process children recursive True           proc kill       process kill     proc   subprocess Popen   infinite app    param    shell True  try      proc wait timeout 3  except subprocess TimeoutExpired      kill proc pid

User · Answer

None of these answers worked for me so Im leaving the code that did work  In my case even after killing the process with  kill   and getting a  poll   return code the process didn t terminate  Following the subprocess Popen documentation    quot    in order to cleanup properly a well-behaved application should kill the child process and finish communication    quot   proc   subprocess Popen      try      outs  errs   proc communicate timeout 15  except TimeoutExpired      proc kill       outs  errs   proc communicate    In my case I was missing the proc communicate   after calling proc kill    This cleans the process stdin  stdout     and does terminate the process

User · Answer

When shell True the shell is the child process  and the commands are its children  So any SIGTERM or SIGKILL will kill the shell but not its child processes  and I don t remember a good way to do it   The best way I can think of is to use shell False  otherwise when you kill the parent shell process  it will leave a defunct shell process

User · Answer

I could do it using   from subprocess import Popen  process   Popen command  shell True  Popen  TASKKILL  F  PID  pid   T  format pid process pid     it killed the cmd exe and the program that i gave the command for    On Windows

User · Answer

Send the signal to all the processes in group      self proc   Popen commands               stdout PIPE               stderr STDOUT               universal newlines True               preexec fn os setsid       os killpg os getpgid self proc pid   signal SIGHUP      os killpg os getpgid self proc pid   signal SIGTERM

User · Answer

There is a very simple way for Python 3 5 or    Actually tested on Python 3 8  import subprocess  signal  time p   subprocess Popen   cmd    shell True  time sleep 5   Wait 5 secs before killing p send signal signal CTRL C EVENT   Then  your code may crash at some point if you have a keyboard input detection  or sth like this  In this case  on the line of code function where the error is given  just use  try      FailingCode  here goes the code which is raising KeyboardInterrupt except KeyboardInterrupt      pass  What this code is doing is just sending a  quot CTRL C quot  signal to the running process  what will cause the process to get killed

User · Answer

Although it is an old question  it has a high google rank  so I decided to post an answer with the new method someone can use in python 3 to manage this easily and with confidence  as of python 3 5 you there is a new method added to subprocess package called run    As the documentation says   It is the recommended approach to invoking sub processes for all use cases it can handle  For more advanced use cases  the underlying Popen interface can be used directly   The subprocess run     Runs a command described by args  Wait for the command to complete  then return a CompletedProcess instance   for example one can run this snippet within a python console   gt  gt  gt  subprocess run   quot ls quot    quot -l quot       doesn t capture output CompletedProcess args   ls    -l    returncode 0   P S  In case of the OP s specific question  I wasn t able to reproduce his problem  commands I run with popen   are terminating properly

User · Answer

Use a process group so as to enable sending a signal to all the process in the groups  For that  you should attach a session id to the parent process of the spawned child processes  which is a shell in your case  This will make it the group leader of the processes  So now  when a signal is sent to the process group leader  it s transmitted to all of the child processes of this group   Here s the code   import os import signal import subprocess    The os setsid   is passed in the argument preexec fn so   it s run after the fork   and before  exec   to run the shell  pro   subprocess Popen cmd  stdout subprocess PIPE                          shell True  preexec fn os setsid    os killpg os getpgid pro pid   signal SIGTERM     Send the signal to all the process groups

User · Answer

As Sai said  the shell is the child  so signals are intercepted by it -- best way I ve found is to use shell False and use shlex to split the command line   if isinstance command  unicode       cmd   command encode  utf8   args   shlex split cmd   p   subprocess Popen args  stdout subprocess PIPE  stderr subprocess STDOUT    Then p kill   and p terminate   should work how you expect

User · Answer

p   subprocess Popen cmd  stdout subprocess PIPE  shell True  p kill     p kill   ends up killing the shell process and cmd is still running   I found a convenient fix this by   p   subprocess Popen  exec     cmd  stdout subprocess PIPE  shell True    This will cause cmd to inherit the shell process  instead of having the shell launch a child process  which does not get killed   p pid will be the id of your cmd process then   p kill   should work   I don t know what effect this will have on your pipe though

[python] How to terminate a python subprocess launched with shell=True

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