Linux Process Management Guide: Master ps, top, and kill Commands

Understanding process management is crucial for Linux system administration. This guide covers essential commands for monitoring and controlling processes.

Table of Contents

Viewing Processes

Using ps Command

ps aux

Output:

$ ps aux
USER       PID  %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1   0.0  0.0 225868  9288 ?        Ss   Oct30   0:08 /sbin/init
user      2451   0.1  0.2 3246504 42716 ?      Sl   10:00   0:12 firefox

Process Tree View

pstree

Process Monitoring

Using top Command

top

Output:

top - 12:00:00 up 2 days, 3:45, 2 users, load average: 0.52, 0.58, 0.59
Tasks: 180 total,   1 running, 179 sleeping,   0 stopped,   0 zombie
%Cpu(s):  5.9 us,  2.3 sy,  0.0 ni, 91.4 id,  0.3 wa,  0.0 hi,  0.1 si
MiB Mem :  15951.3 total,   7855.5 free,   4589.2 used,   3506.6 buff/cache

Interactive Quiz

Question 1

What command would you use to find the PID of a specific process?

pgrep process_name
# or
ps aux | grep process_name

Question 2

How do you terminate a process gracefully?

kill -15 PID
# or
killall process_name

Process Control

Kill Commands

kill -9 1234        # Force kill
kill -15 1234       # Graceful termination
killall firefox     # Kill all Firefox processes

Process Priority

nice -n 10 command  # Start with lower priority
renice +5 -p 1234   # Change priority

Best Practices

1. Always try graceful termination first
2. Monitor system resources regularly
3. Use appropriate nice values
4. Document critical processes
5. Set up process monitoring

Troubleshooting

Common Issues and Solutions

# Find zombie processes
ps aux | grep 'Z'

# Kill unresponsive process
kill -9 $(pgrep unresponsive_app)

Conclusion

Process management is essential for maintaining a healthy Linux system. Regular monitoring and proper control ensure optimal system performance.

What’s Next in the Series?

• Text Processing with Grep and Sed
• Network Commands Guide
• System Monitoring Tools
• Bash Scripting Basics