ps

Overview

The ps command displays information about active processes running on the system. It provides a snapshot of the current processes.

Syntax

ps [options]

Common Options

Option Description
-e Show all processes
-f Full format listing
-l Long format
-u username Show processes for specified username
aux Show all processes in BSD format
-C cmdname Select by command name
--sort Sort by specified criteria

Key Use Cases

  1. Monitor system processes
  2. Troubleshoot performance issues
  3. Find resource-intensive processes
  4. Check process status and details

Examples with Explanations

Example 1: Show all processes

ps -ef

Shows all processes in full format

Example 2: Show process tree

ps -ejH

Displays process hierarchy in a tree format

Example 3: Show processes by user

ps -u username

Shows processes owned by specified user

Understanding Output

Standard columns in ps output: - PID: Process ID - TTY: Terminal type - TIME: CPU time used - CMD: Command name - %CPU: CPU usage - %MEM: Memory usage - VSZ: Virtual memory size - RSS: Resident set size

Common Usage Patterns

  1. Find all processes using a lot of CPU:

    ps aux --sort=-%cpu

  2. Find process by name:

    ps -C processname

  3. Show process hierarchy:

    ps -ejH

Performance Analysis

  • Use ps with top or htop for real-time monitoring
  • Combine with grep to filter specific processes
  • Use sorting options to identify resource-intensive processes

Additional Resources