The /proc Filesystem

If you need to gather information about the processes running on your machine, you can use the /proc filesystem. There's a section about it in the Processes chapter of the QNX Neutrino Programmer's Guide. This appendix describes the main features of the /proc filesystem so you can use it in your own utilities.

CAUTION:

This interface is intended for gathering information and debugging. Don't use it in production systems to control the behavior of processes and threads.

First of all, the /proc filesystem is a virtual filesystem — it doesn't actually exist on disk; it exists only as a figment of the process manager's imagination.

The /proc filesystem contains a number of entities:

directories, one per process, for every process running in the system
the boot subdirectory — a “mini” filesystem that contains the files from the startup image
the (hidden) mount subdirectory.

Our main focus in this chapter is the first item, the directories describing each process in the system. We'll describe the functions available to get information about the processes (and their threads).

For completeness, however, we'll just briefly mention the other two items.