10 Linux Commands Every Pune DevOps Fresher Should Master (2026)

The list

1. 1

   grep + ripgrep — searching files

   grep searches text by pattern: `grep -r 'ERROR' /var/log/` (recursive), `grep -i` (case-insensitive), `grep -v` (invert), `grep -E` (extended regex), `grep -A 5 -B 2` (5 lines after, 2 before). Modern alternative: rg (ripgrep) — faster, respects .gitignore by default, sane defaults.

   Why it matters: Asked at ~90% of Pune DevOps interviews. Walking through log inspection with grep flags signals operational fluency.

   Best for: Foundation; you'll use this every day in production.

2. 2

   find + locate — finding files

   find searches by attributes: `find /var/log -name '*.log' -mtime -7` (modified in last 7 days), `find . -size +100M` (over 100MB), `find / -user www-data` (owned by user), `find . -exec rm {} \;` (delete matched files — careful!). locate uses a prebuilt index for fast name-only searches.

   Why it matters: Asked at ~60% of Pune rounds. Walk through 'how would you find files modified by a specific user yesterday over a certain size' to demonstrate depth.

   Best for: File system inspection; auditing + cleanup work.

3. 3

   ps + top + htop — process inspection

   ps aux: snapshot of all processes; ps aux --sort=-%mem | head: top memory consumers. top: live updating process view; htop: nicer interactive top. Look for high CPU, high memory, runaway processes. Press k in htop to kill; SHIFT+F to filter.

   Why it matters: Asked at ~75% of Pune rounds. 'Server is slow, what do you check?' is the canonical question — ps + top + htop is part of the answer.

   Best for: Performance troubleshooting; expected at every tier.

4. 4

   df + du — disk usage

   df -h: filesystem disk usage (human-readable). du -sh /var/log/*: size of each item in a directory. `du -sh . | sort -h` (sort by size). Quickly find what's filling a disk. Common production issue: log files growing unbounded.

   Why it matters: Asked at ~60% of Pune rounds. 'Disk is at 95%, what do you do?' → df + du + investigate + truncate or rotate logs.

   Best for: Production troubleshooting; disk-space alerts are common.

5. 5

   netstat + ss + lsof — network + open files

   ss -tulnp: listening ports + processes (modern replacement for netstat). lsof -i :8080: what process holds port 8080. lsof -p PID: all files opened by a process (network sockets count). Use these to debug 'port already in use' errors + identify zombie listeners.

   Why it matters: Asked at ~50% of Pune rounds. Networking interview questions often involve walking through these commands.

   Best for: Networking + connection troubleshooting.

6. 6

   curl + wget — HTTP testing + downloads

   curl -i URL: show response headers + body. curl -X POST -H 'Content-Type: application/json' -d '{json}' URL: POST request. curl --resolve example.com:443:1.2.3.4 URL: test DNS routing. wget: focused on file download with retries. Both are essential for API debugging + scripted downloads.

   Why it matters: Asked at ~55% of Pune rounds. Knowing curl flags fluently signals API + debugging maturity.

   Best for: API + network debugging.

7. 7

   chmod + chown + chgrp — permissions + ownership

   chmod 755 file: rwxr-xr-x (owner full, others read+execute). chmod +x script.sh: make executable. chown user:group file: change owner + group. chmod -R 644 dir: recursive (use carefully). Understand the octal notation (read=4, write=2, execute=1, sum permissions).

   Why it matters: Asked at ~50% of Pune rounds. Pune BFSI + security-conscious interviews probe permissions depth.

   Best for: Security + filesystem permissions; foundational.

8. 8

   systemctl + journalctl — service + log management

   systemctl status nginx: service status. systemctl restart nginx: restart. systemctl enable nginx: start on boot. journalctl -u nginx -f: tail nginx logs (-f = follow). journalctl --since '1 hour ago': time-filtered logs. systemd is the universal Linux init system since ~2015.

   Why it matters: Asked at ~70% of Pune rounds. Production server work assumes systemctl + journalctl fluency.

   Best for: Service management + log diagnosis.

9. 9

   sed + awk — text transformation in pipelines

   sed for find-and-replace: `sed -i 's/old/new/g' file.txt` (in-place edit). awk for column-aware text processing: `awk '{print $2}' file.txt` (2nd column), `awk -F',' '{sum+=$3} END {print sum}'` (sum CSV 3rd column). Combine with grep + cut + sort + uniq for log analysis pipelines.

   Why it matters: Asked at ~40% of Pune rounds. Log-analysis questions often expect sed/awk fluency at fresher tier.

   Best for: Data manipulation in pipelines; senior-fresher signal.

10. 10

    tar + gzip + zip — archives + compression

    tar -czf archive.tar.gz dir/: create gzipped tar. tar -xzf archive.tar.gz: extract. tar -tzf archive.tar.gz: list contents without extracting. gzip file: compress in place. zip -r archive.zip dir/: cross-platform-friendly archive. Backup + transfer workflows depend on these.

    Why it matters: Asked at ~30% of Pune rounds. Backup workflows + log rotation patterns assume tar fluency.

    Best for: Backup + transfer workflows.