🖥️ Linux Process Management for Beginners: A Day in the Life of a Junior Sysadmin

You're the new Junior Sysadmin at a small but busy tech startup. It's your first week on the job, and you've just been asked to monitor, troubleshoot, and control running processes on the company's servers.

In this guide, you’ll learn how to monitor and manage Linux processes through hands-on examples. We’ll create dummy processes, explore real-time tools, and learn how to gently—or forcefully—handle misbehaving tasks.

📚 Table of Contents

• 🔧 Setting Up Your Practice Environment
• 📊 Monitoring Processes in Real-Time
• 🔍 Viewing Detailed Process Info
• 🧼 Cleaning Up Processes
• 🎯 Managing Background Jobs
• ⚙️ Changing Process Priority
• 🧪 Bonus Tools to Try
• 🧠 Summary: Command Cheat Sheet

🔧 Setting Up Your Practice Environment

Simulate real-world tasks by launching test processes:

Create a working directory:

mkdir ~/process-lab && cd ~/process-lab

Create an infinite loop script:

echo -e '#!/bin/bash
while true; do echo "Working..."; sleep 5; done' > worker.sh

🔍 Breakdown of What It Does:

echo -e
echo: Prints text to the terminal or into a file.

-e: Enables interpretation of backslash escapes (like \n for newline).

#!/bin/bash
This is a shebang. It tells the system to execute the script using the Bash shell.

while true; do echo "Working..."; sleep 5; done
This is an infinite loop:

while true; means “loop forever.”

echo "Working..." prints the message to the screen.

sleep 5 pauses for 5 seconds between each print to avoid spamming.

done marks the end of the loop block.

worker.sh
Redirects the whole output into a file called worker.sh.

If the file exists, it will be overwritten.

Make it executable:

chmod +x worker.sh

Note: Review the kill cmd before proceeding, you'll thank yourself in a few moments.

Run it in the background:

./worker.sh &

Note: Record the process ID (PID)

By now you are annoyed because Working... continues to print to screen. But we can discard the output with /dev/null or redirect it to a log by editing the script. Example here:

#!/bin/bash
while true; do
  echo "Working..." >> ~/process-lab/worker.log
  sleep 5
done

I don't need the output for this example, so I will discard them.

#!/bin/bash
while true; do
  echo "Working..." >> /dev/null
  sleep 5
done

Create a CPU-intensive process:

yes > /dev/null &

• yes prints "y" repeatedly; /dev/null discards the output. This simulates high CPU usage.

📊 Monitoring Processes in Real-Time

top

top

• What it does: Shows real-time info on CPU, memory, and processes.
• Navigation tips: Use q to quit, P to sort by CPU, and M to sort by memory.

htop

htop

• What it does: A friendlier alternative to top with color and interactivity.
• Useful features: Scrollable list, search with /, kill with F9.
• Install it:

sudo dnf install htop

Note: If htop is not available by default, try these additional steps:

Enable EPEL repository:

sudo dnf install epel-release

Update your package index (optional):

sudo dnf update

🔍 Viewing Detailed Process Info

ps aux

ps aux | grep worker.sh

• ps: Shows process snapshot.
• a: Show processes from all users.
• u: Display in user-oriented format.
• x: Include background and non-terminal processes.
• grep worker.sh: Filter to find our script.

pstree -p

pstree -p

• What it does: Displays processes as a tree with PIDs.
• Great for spotting parent-child relationships.

🧼 Cleaning Up Processes

kill <PID>

kill 1234

• What it does: Sends signal (default: SIGTERM) to request graceful stop.

kill -9 <PID>

kill -9 1234

• -9 = SIGKILL: Forces termination without cleanup.
• Use only if normal kill doesn't work.

pkill <name>

pkill worker.sh

• Ends all processes matching the name worker.sh.
• Safer than hunting for PIDs manually.

🎯 Managing Background Jobs

Background a command with &

sleep 60 &

• Launches sleep as a background job.

Check jobs

jobs

• Shows background jobs for current session.

Bring job to foreground

fg %1

• %1: Refers to job number 1.

Send to background again

bg %1

⚙️ Changing Process Priority

nice

nice -n 10 ./worker.sh &

• -n 10: Starts the process with a niceness of 10 (lower priority).
• Range: -20 (high priority) to 19 (low priority).

renice

renice -n 5 -p 1234

• Changes priority of process 1234 to niceness 5.
• Requires root to decrease niceness (i.e., increase priority).

🧪 Bonus Tools to Try

systemctl status <service>

systemctl status sshd

• Checks if the sshd service is running.
• Useful for managing system-level daemons.

watch

watch -n 1 ps aux | grep worker

• Repeats a command every second.
• Great for monitoring state changes.

strace

strace -p <PID>

• Traces system calls for a process.
• Advanced troubleshooting tool.

🧠 Summary: Command Cheat Sheet

✅ Wrap Up

Linux process management isn't just about knowing commands—it's about understanding how and when to use them. Set up a test environment, try each command, and you'll gain confidence in keeping your systems stable and responsive.

Happy sysadmin-ing!