/proc file system contains the informations about,

  • Kernel
  • Hardware
  • Running Process

All the files under /proc can be viewed by the cat command.
/proc/<PID> file  contains the information about the running process which holds that Process ID –

These informations used by  the commands like ps and top to display the running process

For example, If you run the httpd service and it has 3992 process ID, Its information will be located in   /proc/ <3992 >

Some Important files under /Proc:

/proc/cpuinfo  – contains the information about CPU.

/prc/mdstat – contains the information about RAID about md devices (used by  mdadm command) 

/proc/meminfo and /proc/swaps – Contain the information about memory usage and swap  usage (used by free and vmstat commands)

/proc/modules – Contains the list of modules. It can be viewed by the lsmod command.

/proc/mounts contain the mounted file system information 

/proc/partitions – Contains the partitions information 

/proc/net – contains the information about networking (Used by ifconfig and netstat ) 

/proc/version – Contains Linux kernel version (uname –v)

/proc/sys/kernel/hostname – contains system hostname

/proc/sys/net/ipv4/ip_forward –  You can make IP forwarding ON or OFF by editing this file. the same can be done with sysctl -w as well