Linux System Administration & Automation

This is the 2nd week of 90 Days of DevOps - 2025 Edition! by Shubham Londe. Where I explored Linux system administration and automation, covering essential topics such as user management, file permissions, log analysis, process control, volume mounts, and shell scripting.

I loved this challenge because I had to explore and learn the new commands and concepts like htop, mount or loop devices. which enhanced my knowledge and widened the my knowledge over linux. I have provide a the screen shots of my task below

1️⃣ User & Group Management

• Create a user devops_user and add them to a group devops_team.

• Create a user devops_user and add them to a group devops_team.

  → command for this task would be sudo usermod -aG devops_team devops_user

• Restrict SSH login for certain users in /etc/ssh/sshd_config.

  → Add this line DenyUsers <username>

2️⃣ File & Directory Permissions

• Create /devops_workspace and a file project_notes.txt.

• Set permissions:

  • Owner can edit, group can read, others have no access.

• Use ls -l to verify permissions.

3️⃣ Log File Analysis with AWK, Grep & Sed

• Use grep to find all occurrences of the word "error" ( there was no error word in the log file )

• Use awk to extract timestamps and log levels.

  

• Use sed to replace all IP addresses with [REDACTED] for security.

  → sed -E 's/([0-9]{1,3}\.){3}[0-9]{1,3}/[REDACTED]/g' Linux_2k.log

  

4️⃣ Volume Management & Disk Usage

• Create a directory /mnt/devops_data.

• Mount a new volume (or loop device for local practice).

• Verify using df -h and mount | grep devops_data.

5️⃣ Process Management & Monitoring

• Start a background process (ping google.com > ping_test.log &).

• Use ps, top, and htop to monitor it

• → PS

  

  → TOP

  

  → HTOP

  

  6️⃣ Automate Backups with Shell Scripting

  • Write a shell script to back up /devops_workspace as backup_$(date +%F).tar.gz.

  • Save it in /backups and schedule it using cron.

  • Make the script display a success message in green text using echo -e.