⚙️ What Is a Process in Linux?

A process is an active instance of a running program.
Every application or script you execute creates a process with a unique PID (Process ID).

Linux processes are categorized as:

Foreground (interactive):
Visible and directly controlled in the terminal.
Background (non-interactive):
Run silently without blocking your shell.

📌 Example:
firefox runs in the foreground, while cron jobs run in the background.

📋 Viewing Processes in Linux

The following commands help you inspect active processes and system load:

Common Process Viewing Commands

Command	Purpose	Example
`ps aux`	List all running processes	Shows PID, CPU%, MEM%
`top`	Real-time resource monitor	Interactive system view
`htop`	Enhanced top (if installed)	Color-coded, scrollable process list
`pgrep`	Search processes by name	`pgrep nginx`

🛑 Controlling Linux Processes

You can end, pause, or resume processes using these commands:

Process Control Commands

Command	Purpose	Example
`kill PID`	Send signal (default: SIGTERM)	`kill 2345`
`kill -9 PID`	Force kill (SIGKILL)	`kill -9 2345`
`pkill name`	Kill by process name	`pkill chrome`
`jobs`	View background jobs	Lists job IDs
`fg %1`	Bring job 1 to foreground	Used for suspended jobs
`bg %1`	Resume job in background	Runs silently

⚖️ Managing Process Priorities Using nice & renice

Linux uses nice values (−20 to +19) to adjust process priority.

Lower nice value = Higher priority
Higher nice value = Lower priority

Priority Tuning Commands

Command	Purpose	Example
`nice -n 10 command`	Start a process with lower priority	`nice -n 10 ./backup.sh`
`renice -n 5 -p 1234`	Change priority of running process	Adjusts process 1234 to nice value 5

🧠 Pro Tips for Process Management

✔ Use top or htop to quickly identify CPU/memory hogs
✔ Use kill -9 only as a last resort
✔ Avoid renicing system-critical services (e.g., sshd, systemd)
✔ Run long scripts in background:
./script.sh &

🚀 What’s Next?

Post #5:
We’ll dive into Linux package management — using apt, yum, and dnf to install, update, and remove software safely.

Managing Linux Processes: Monitor, Control, and Optimize with ps, top, kill, and nice