Guillaume Redoulès

How to check Linux process information?

  2. Linux
  3. Bash

How to check Linux process information (CPU usage, memory, user information, etc.)?

You need to use the ps command combined with the grep command. In the example, we want to check the information on the nginx process :

ps aux | grep  nginx

It would return the output :

root      9976  0.0  0.0  12272   108 ?        S<s  Aug12   0:00 nginx: master process /usr/bin/nginx -g pid /run/nginx.pid; daemon on; master_process on;
http     16780  0.0  0.0  12384   684 ?        S<   Aug12   4:11 nginx: worker process
http     16781  0.0  0.0  12556   708 ?        S<   Aug12   0:24 nginx: worker process
http     16782  0.0  0.1  12292   744 ?        S<   Aug12   2:43 nginx: worker process
http     16783  0.0  0.1  12276   872 ?        S<   Aug12   0:24 nginx: worker process
admin    17612  0.0  0.1   5120   864 pts/4    S+   11:22   0:00 grep --color=auto nginx

The columns have the following order : USER;PID;%CPU;%MEM;VSZ;RSS;TTY;STAT;START;TIME;COMMAND

  • USER = user owning the process
  • PID = process ID of the process
  • %CPU = It is the CPU time used divided by the time the process has been running.
  • %MEM = ratio of the process’s resident set size to the physical memory on the machine
  • VSZ = virtual memory usage of entire process (in KiB)
  • RSS = resident set size, the non-swapped physical memory that a task has used (in KiB)
  • TTY = controlling tty (terminal)
  • STAT = multi-character process state
  • START = starting time or date of the process
  • TIME = cumulative CPU time
  • COMMAND = command with all its arguments

Interactive display

If you want an interactive display showing in real time the statistics of the running process you can use the top command. If htop is available on you system, use this instead.