Some common Files in /proc

1. pid/ holds information about process number pid. The kernel maintains a directory holding process information for every process
2. pid/cmdline holds the command which was used to begin the process (using null characters to divided arguments)
3. pid/environ holds a list of the environment variables which are available to the process
4. pid/exe holds a link to the program which is running in the process
5. pid/fd/ is a directory holding a link to each of the files in which the process has opened
6. pid/mem holds the memory contents of the process
7. pid/stat holds the process status information
8. pid/statm holds the process memory usage information

The /proc file system is not a file system in the standard sense. The huge files found in /proc are the address spaces of running processes, only just the PID of the running processes. The owner and group owner of every file are the real-UID and primary group of the process's owner.

A sample listing from /proc is as given below

ls -l /proc

total 43384

-rw---       1 root         root                  0               Apr  3             20:07 00000

-rw---       1 root         root           393216            Apr  3              20:07 00001

-rw---       1 root         root                  0              Apr  3              20:07 00002

-rw---       1 root         root                  0               Apr  3              20:07 00003

-rw---       1 root         root         1695744            Apr  3             20:07 00081

-rw---       1 root         root         1597440            Apr  3             20:07 00083

-rw---       1 root         root         1777664             Apr  3             20:08 00096