shodowsjedi shodowsjedi - 19 days ago 4x
Linux Question

What is a .pid file and what does it contain?

I recently come across a file with the extension .pid and explored inside it but didn't find much. The documentation says:

A Pid-File is a file containing the process identification number (pid) that is stored in a well-defined location of the filesystem thus allowing other programs to find out the pid of a running script.

Can anyone shed more light on this, or guide me to details of what's contained in the pid file?


The pid files contains the process id (a number) of a given program. For example, Apache HTTPD may write it's main process number to a pid file - which is a regular text file, nothing more than that - and later use the information there contained to stop itself. You can also use that information (just do a cat to kill the process yourself, using echo | xargs kill