DevOps Day 3 - Exploring Linux Permissions & Users

Jayanth BJayanth B
2 min read

Hey folks! Sharing my Day 3 journey as part of my DevOps learning adventure. Today, I got hands-on with one of the core building blocks for anyone working in backend, automation, or cloud environments: Linux users, groups, and permissions. Here’s how my exploration went—and what I learned!

What I Practiced

Understanding Users & Groups

  • Learned that every action on a Linux system happens as a specific user—either a regular user, root, or a service account.

  • Groups are just collections of users to help manage permission settings for teams or projects.

Commands I tried:

bashwhoami             # Shows current user
groups             # Lists groups the user belongs to
cut -d: -f1 /etc/passwd   # Quick list of all users

Permissions: The rwx Model

I found out how crucial proper permissions are—not just for security, but also for teamwork. Linux breaks file and folder permissions into three chunks:

  • User (owner)

  • Group

  • Others

And each chunk is represented as:

  • r = read (4)

  • w = write (2)

  • x = execute (1)

For example, -rw-r--r-- means the user can read/write, group and others can only read.

Modifying Permissions and Ownership

chmod – Changing Permissions

bashchmod 755 script.sh      # User can rwx, group/others can rx
chmod o-w secret.txt     # Remove write for others

chown – Changing Ownership

bashsudo chown jayanth myfile.txt   # Set myself as owner

chgrp – Changing Group

bashsudo chgrp devops myfile.txt    # Change group to 'devops'

My Mini-Exercises

  • Created a file, messed around with chmod and chown.

  • Made a quick script to practice:

      bashtouch explore.txt
      chmod 600 explore.txt
      sudo chown $USER explore.txt
      ls -l explore.txt
    

    This let me see how only the owner has read/write, and practice switching ownership.


Reflections & Tips

  • Even simple permission mistakes can create big security gaps or block workflows—so always check before changing to 777!

  • Knowing which user/group needs access helps me set up safer automation scripts and shared folders.

  • Planning to make a quick cheatsheet of chmod, chown, and chgrp (needed this more than once today!).


What’s Next?

Tomorrow, I’ll be tackling file handling and redirection—using powerful Linux commands to view, filter, and manage output/input. It’s getting more interesting!

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Jayanth B
Jayanth B