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LaTerral Williams
LaTerral Williams

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👩🏾‍💻 Welcome to devsrv01: Your First Day as a Linux Sysadmin

#cloudwhistler #linux #opensource #cloud

👩🏾‍💻 You’ve been hired as a junior sysadmin at a mid-sized company running RHEL 9 servers. You’re assigned to configure, manage, and troubleshoot a new development server called devsrv01.

You have one day to complete the tasks before the system is handed off to the developers.

📑 Table of Contents

🔧 1. System Initialization & Host Configuration 

hostnamectl set-hostname devsrv01
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Sets the system hostname.

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timedatectl set-timezone America/Chicago
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Sets system timezone.

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systemctl get-default
systemctl set-default multi-user.target
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Checks and sets the default systemd boot target. multi-user.target is equivalent to runlevel 3 (non-GUI, multi-user mode).

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👥 2. User and Group Management 

groupadd devteam
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Creates a group named devteam.

useradd -m -G devteam alice
useradd -m -G devteam bob
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Creates users alice and bob with home directories and adds them to devteam group.

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passwd alice
passwd bob
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Sets or updates user passwords.

🔐 3. Project Directory & Permissions 

mkdir -p /devproj/docs
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Creates the project directory and a subdirectory docs.

chown root:devteam /devproj
chmod 2775 /devproj
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Sets ownership to root:devteam, then applies 2775 permission:

  • 2: SGID bit (preserves group ID)
  • 7: Owner read/write/execute
  • 7: Group read/write/execute
  • 5: Others read/execute 
chmod +t /devproj/docs
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Applies the Sticky Bit so only file owners can delete their own files.

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🧝 4. ACLs for Fine-Grained Access 

touch /devproj/notes.txt
setfacl -m u:bob:rw /devproj/notes.txt
setfacl -m u:alice:r-- /devproj/notes.txt
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Adds read/write permission for Bob and read-only for Alice on notes.txt.

getfacl /devproj/notes.txt
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Displays the ACLs applied.

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📦 5. Archiving and Compression 

mkdir /backups
tar -czvf /backups/devproj.tar.gz /devproj
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Creates a compressed archive (.tar.gz) of /devproj into /backups.

  • -c: create archive
  • -z: use gzip
  • -v: verbose output
  • -f: filename

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tar -xzvf /backups/devproj.tar.gz -C /tmp
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Extracts the archive into /tmp.

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⏱️ 6. Schedule Daily Archival with Cron 

crontab -e
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Opens the crontab editor.

Example cron entry:

0 0 * * * /usr/bin/tar -czf /backups/devproj_logs_$(date +\%F).tar.gz /devproj/docs
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Runs a gzip backup of /devproj/docs every day at midnight.

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I added the second cronjob to run every minute for testing. Be sure to enable and start the cron service.

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Note: I had difficulty getting the cronjob to run. After troubleshooting I discovered the user account I used to create the cronjob did not have permissions to /backups because it belonged to root:root. You may resolve this by updating the permissions or create the cronjobs as root. I chose to create the cronjobs as root.


⚙️ 7. Manage Services and Background Processes 

systemctl enable sshd
systemctl start sshd
systemctl status sshd
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Enables, starts, and checks the status of the SSH service.

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echo -e '#!/bin/bash\nwhile true; do echo "Running..."; sleep 10; done' > loop.sh
chmod +x loop.sh
./loop.sh &
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Creates and runs a simple infinite loop script in the background.

If the previous fails due to permission denied; try the following:

Use sudo tee (Best Practice for Redirection)

echo -e '#!/bin/bash\nwhile true; do echo "Running..."; sleep 10; done' | sudo tee loop.sh > /dev/null
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  • tee receives the content from echo and writes it as root.

  • /dev/null prevents duplicate output to your screen.

The above script would still print to screen and did not seem to work as a single line. If you have the same issue try the following:

./loop.sh > /dev/null 2>&1 &


ps aux | grep loop.sh
pkill loop.sh
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ps aux shows all processes. pkill terminates the process.

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💾 8. Check Storage and Memory 

df -h
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Shows disk usage in human-readable format.

du -sh /devproj
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Shows the size of /devproj directory.

free -m
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Displays memory usage in megabytes.

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📘 9. Use Help and Documentation 

man chmod
tldr tar
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man provides manual pages. tldr shows simplified examples.

Need an assist with tldr? Check out my article on finding command info in Linux: Need Info on a Linux Command?

✅ Final Tips

  • Use sudo wisely when writing files or starting services; especially with redirection (>) where sudo tee is more reliable.

  • Practice creating users, groups, and directories in /tmp to avoid permission issues.

  • Enable and verify cron jobs:

sudo systemctl enable --now crond
cat /var/log/cron  # Check if jobs ran
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This scenario attempts to reflect real-world scenarios and can be repeated in a VM or lab environment.

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