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In Linux-based operating systems, there is support for both foreground and background job processing. A job in this context is just a command launched from a terminal window, and any running command is a process.
Why Manage Jobs?
By default, all jobs in Linux execute in the foreground. Foreground jobs run directly from the shell. When you run one foreground job, you must wait for shell access until the job completes before running other jobs. While this is fine for quick jobs, it becomes challenging when a job takes hours to complete – especially when working with a single terminal window (SSH session or web console).
In such cases, you can run the job in the background, which executes at low priority and frees the shell for other tasks while the job continues running.
You Should Know:
Basic Process Management Commands:
Run a command in the foreground (default) $ long_running_command Send a foreground process to background Ctrl+Z Suspend the process bg Resume it in background Start a command directly in background $ long_running_command & List all jobs $ jobs -l Bring background job to foreground $ fg %jobnumber Disown a process to keep it running after terminal closes $ disown -h %jobnumber Use nohup to prevent SIGHUP $ nohup long_running_command &
Advanced Process Control:
View all running processes $ ps aux Kill a process by PID $ kill -9 PID Kill a process by name $ pkill process_name Change process priority $ nice -n 10 long_running_command & Lower priority $ renice -n -5 PID Increase priority Monitor system processes $ top $ htop $ glances
Persistent Process Management:
Use screen for persistent sessions $ screen -S session_name $ long_running_command Ctrl+A then D Detach $ screen -r session_name Reattach Alternative using tmux $ tmux new -s session_name $ long_running_command Ctrl+B then D Detach $ tmux attach -t session_name Reattach Systemd service management (for persistent services) $ sudo systemctl start service_name $ sudo systemctl enable service_name $ sudo journalctl -u service_name -f View logs
What Undercode Say:
Mastering foreground and background processes is essential for efficient Linux system administration. The key is knowing when to use each approach – foreground for interactive tasks requiring attention, background for long-running processes, and tools like screen/tmux for persistent sessions.
Additional useful commands for process management include:
Find process using specific port $ sudo lsof -i :port_number $ sudo netstat -tulnp | grep port_number Monitor disk I/O by process $ iotop View process tree $ pstree -p Check process memory usage $ pmap PID Limit process resources $ ulimit -a View limits $ prlimit --pid PID --nproc=100 Set limit Process timing information $ time command $ /usr/bin/time -v command Process signals overview $ kill -l Continuous process monitoring $ watch -n 1 'ps aux | grep process_name'
Expected Output:
When properly managing foreground and background processes, you should see:
– Immediate terminal availability when using `&` or `bg`
– Continued process execution after terminal closure when using nohup, disown, or terminal multiplexers
– Proper job listings when using `jobs -l`
– Clean process termination when using appropriate `kill` signals
– Persistent sessions that survive network interruptions when using `screen` or `tmux`
References:
Reported By: Divine Odazie – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
