Every server you will ever SSH into runs Linux. Every Docker container, every Kubernetes node, every cloud VM — the ground beneath every DevOps tool is a Linux filesystem with permissions, users, and packages. Engineers at Zerodha, Razorpay, and PhonePe spend their careers on Linux servers, and this pillar covers the foundation they build on every day.
What This Pillar Covers
- Navigating the Linux Filesystem Hierarchy Standard — what lives in /etc, /var, /proc, and why
- Reading and setting file permissions with chmod, chown, and ACLs in production contexts
- Managing users, groups, and sudo access for least-privilege server access control
- Installing, updating, and pinning package versions with apt, yum, and dnf across distributions
Who This Is For
DevOps engineers, backend developers, and anyone who SSHs into production servers and needs to work confidently at the command line without guessing.
Why This Matters in Production
At PhonePe, a misconfigured file permission on a secrets file exposed database credentials to every process on the server. Understanding Linux permissions is not optional — it is the first line of defence for every production system.
Prerequisites
- Basic familiarity with a terminal or command prompt
- Understanding of what a file and directory are
- No prior Linux experience required