ps — report process status

Brief:
- ps shows information about running processes.
- Often combined with options to display all processes and their details.

Syntax:
- ps
- ps aux             # show all processes for all users with extended info (BSD style)
- ps -ef             # show all processes in full-format listing (SysV style)
- ps aux | grep ssh  # find processes related to 'ssh'

Examples:
- ps aux | grep python
- ps -ef | grep nginx

Tips:
- ps aux vs ps -ef are similar but from different conventions (BSD vs SysV).
- Use top or htop for a dynamic, real-time view.
- Combine with grep to quickly filter by command or user.
