DevOps for Beginners: Linux Basics You Can Understand

Hey there! 👋
If you've ever felt like Linux is some scary dark screen full of hacker code, don't worry — you’re not alone. Today, we're diving into a few beginner-friendly Linux tasks that are actually super fun and powerful. And yes, you can do this even if you’ve never used a terminal before.

Let’s go step by step. We’ll cover:

1. User & Group Management

2. File & Directory Permissions

3. Log File Analysis using AWK, Grep & Sed

Let’s gooo! 🚀

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1️. User & Group Management: Who’s Allowed to Do What?

Think of Linux like a shared apartment. Every person (user) has their own keys, and groups of people can share access to certain rooms (directories).

🧠 What’s What?

• User – a person using the system.

• Group – a collection of users (like a team).

• Permissions – control what users/groups can read/write/execute.

All of this info lives in special files:

• /etc/passwd – stores user info.

• /etc/group – stores group info.

✅ Task: Create a User & Give Sudo Powers

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

• Set a password and grant sudo acces

Steps:

# Create a user
sudo useradd -m devops_user

# Create a group
sudo groupadd devops_team

# Add user to group
sudo gpasswd -a devops_user devops_team

# Set a password
sudo passwd devops_user

# Give sudo access (admin powers)
sudo gpasswd -a devops_user sudo

🔒 Sudo = Superpowers. It allows a user to run admin-level commands.

✅ Done! You’ve created a user, added them to a group, and handed them some serious power (responsibly, of course).

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2️. File & Directory Permissions: Who Can Access What?

Imagine a file cabinet:

• Owner – the person who created the file.

• Group – their team.

• Others – everyone else.

✅ Task: Create Folder & Set Permissions

Step 1: Create /devops_workspace and a file project_notes.txt.

# Create Group
mkdir devops_workspace

# Create File
touch project_notes.txt

Step 2: Set permissions: - Owner can edit, group can read, others have no access.

# Changing the permission of file
chmod 240 project_notes.txt

• 2 = Owner can write

• 4 = Group can read

• 0 = Others have no access

Step 3: Check it worked

ls -l

You’ll see something like:

--w-r----- 1 devops_user devops_team 0 Apr 15 12:00 project_notes.txt

🔍 Quick Breakdown:
rw- → Owner can read/write
r-- → Group can read
--- → Others get nada

Nice! You've officially locked it down like a pro.

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3️. Log File Analysis: Becoming a Mini Sherlock 🕵️‍♂️

Logs are like the system’s diary. DevOps folks love logs — they help find problems, patterns, and performance issues.

Let’s analyze a log file using the most useful Linux command trio: grep, awk, and sed.

🗂️ Get the Log File

First, download the file (from LogHub GitHub repo, or wherever the Linux_2k.log lives):

get https://your-repo-path/Linux_2k.log

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🔎 Step 1: Find All Errors with grep

grep "authentication failure" Linux_2k.log

grep searches for specific words or patterns. Here, we’re hunting for the word error.

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🕒 Step 2: Extract Timestamps & Log Levels with awk

awk '/authentication failure/ {print $1, $2, $3}' Linux_2k.log

This grabs the first three columns — typically timestamps and log level (like INFO, ERROR).

Want both time & log type? Try:

awk '/authentication failure/ {print $1, $2, $3, $12, $13, $14}' Linux_2k.log

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🛡️ Step 3: Hide IP Addresses with sed

sed -E 's/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/[REDACTED]/g' Linux_2k.log > secure_log.log

This replaces every IP address with [REDACTED] to keep things private.

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💥 Bonus: Find the Most Frequent Log Entry

cat Linux_2k.log | sort | uniq -c | sort -nr | head -10

• sort – arranges lines.

• uniq -c – counts duplicates.

• sort -nr – sorts by count, highest first.

• head -10 – shows top 10.

Boom 💣 — now you know what’s happening most often in your logs.

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👨‍🏫 Final Thoughts

If you made it this far, you’ve done:

• User and group management 🧑‍🤝‍🧑

• File permissions like a gatekeeper 🔐

• Log file analysis like a detective 🕵️

Not bad for someone who thought Linux was all "matrix" stuff, huh?

📌 Pro Tip: Practice these in a safe environment (like a virtual machine or online Linux lab). You’ll get the hang of it faster.

Want more beginner-friendly DevOps magic? Let me know what topic you want next! 💬