I am attempting to do something that is a little risky. Its a private script, but i want to add some security so I don’t accidentally enter an invalid PID.
Currently if a script hangs it will lock up the port it uses, i need to kill the PID and then restart it. I want to add a new argument to this script so i can pass in the old PID and the script will kill that PID before starting again. Using netstat -tulpen i see that there is a program name tied to a PID. I want to make sure that the program name is PHP so i dont shut down a different process by accident. E.g. check that PID 15498 was created by PHP (15498/php)
tcp 0 0 0.0.0.0:1067 0.0.0.0:* LISTEN 0 201425 15498/php
I had a look on the file system and i found a directory for the PID, but all of the files within this directory are empty. /proc/15498
Once i can validate that this is a relatively safe PID to kill i can then run the command to kill it.
exec("kill -SIGKILL 15498");
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Answer
Get the command line from /proc/PID/cmdline, and remove the trailing null byte.
$cmd = trim(file_get_contents("/proc/$pid/cmdline"), " ");