ps

Overview

The ps command displays information about active processes. It provides a snapshot of current processes and their status.

Syntax

ps [options]

Common Options

Option Description
-e All processes
-f Full format
-l Long format
-u user User processes
-p pid Process ID
-C cmd Command name
-o format Output format
--sort key Sort output
-H Process hierarchy
-L Thread info
-m Memory info
aux BSD style

Output Fields

Field Description
PID Process ID
PPID Parent PID
%CPU CPU usage
%MEM Memory usage
VSZ Virtual size
RSS Resident size
TTY Terminal
STAT Process state
START Start time
TIME CPU time
COMMAND Command line

Key Use Cases

  1. Process monitoring
  2. Resource usage
  3. System analysis
  4. Troubleshooting
  5. Performance tuning

Examples with Explanations

Example 1: All Processes

ps -ef

Full process list

Example 2: Process Tree

ps -ejH

Show process hierarchy

Example 3: Custom Format

ps -eo pid,ppid,cmd

Select output fields

Common Usage Patterns

  1. User processes:

    ps -u username

  2. Sort by memory:

    ps aux --sort=-%mem

  3. Process search:

    ps -C processname

Process States

State Description
R Running
S Sleeping
D Uninterruptible
Z Zombie
T Stopped
W Paging
X Dead
< High priority
N Low priority

Additional Resources

Best Practices

  1. Use filters
  2. Check resources
  3. Monitor states
  4. Regular checks
  5. Document findings

Security Considerations

  1. Process visibility
  2. User permissions
  3. System impact
  4. Information leak
  5. Resource usage

Troubleshooting

  1. Missing processes
  2. High resource use
  3. Zombie processes
  4. State issues
  5. Performance problems

Common Formats

  1. Default
  2. BSD style
  3. System V
  4. Custom
  5. Thread view