Cannot kill process group when invoked by PHP

manpreet Best Answer 2 years ago

I have a script spawning two zombies. I can kill the group via kill -- -, but when invoked by the PHP interpreter, that won’t work although killing every single process manually will.

The script is

#!/bin/bash
sleep 1d&
sleep 1d

and the PHP file just invokes it:

From the shell directly:

$ ./spawn&
[1] 19871    
$ pstree -p 19871
spawn(19871)─┬─sleep(19872)
             └─sleep(19873)    
$ kill -- -19871    
$ pstree -p 19871
[1]+  Terminated                 ./spawn

... and via PHP:

$ php -f zomby.php &
[1] 19935    
$ pstree -p 19935
php(19935)───sh(19936)───spawn(19937)─┬─sleep(19938)
                                      └─sleep(19939)
$ kill -- -19937
bash: kill: (-19937) - No matching process found
$ kill -- -19936
bash: kill: (-19936) - No matching process found
$ kill 19939 19938 19937     
$ Terminated    
[1]+  Fertig                  php -f zomby.php

only killing the PHP parent process will work:

$ php -f zomby.php &
[1] 20021

$ pstree -p 20021
php(20021)───sh(20022)───spawn(20023)─┬─sleep(20024)
                                      └─sleep(20025)
$ kill -- -20021

$ pstree -p 20021
[1]+  Terminated                 php -f zomby.php

Any ideas on that?

manpreet 2 years ago

 ‘PID < -1’
      The process group whose identifier is −PID.

$ pstree -p 19935
php(19935)───sh(19936)───spawn(19937)─┬─sleep(19938)
                                      └─sleep(19939)

$ php -f ./zombie.php &
[2] 12882
$ ps  -o pid,ppid,pgid,command | grep -E '[P]GID|[1]2882'
  PID  PPID  PGID COMMAND
12882  1133 12882 php -f ./zombie.php
12883 12882 12882 /bin/bash ./spawn
12884 12883 12882 sleep 1d
12885 12883 12882 sleep 1d

$ ./spawn &
[3] 14213
terdon@tpad foo $ ps  -o pid,ppid,pgid,command | grep -E '[P]GID|[1]4213'
  PID  PPID  PGID COMMAND
14213  1133 14213 /bin/bash ./spawn
14214 14213 14213 sleep 1d
14215 14213 14213 sleep 1d