Sudo Mastery: The Linux Essentials Every DevOps Engineer Needs

Hey everyone,in this blog I am going to revisit all the needful commands one should definitely know before starting their devops journey,not only their functions I will also state how they are used in this very domain. So be ready with your terminal running.

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🔹 1. Shell Navigation & File Operations

These commands are your basic survival toolkit in the Linux shell. They help you move around, list, create, and manage files and directories.

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Making a directory and navigating through it

mkdir Linux_Basics
cd Linux_Basics
touch shellcommands.txt

🧠Explaination

mkdir→ creates a directory named Linux_Basics

cd → changes current directory to Linux_Basics in terminal

touch → creates a file named shellcommands.txt

🧠Bonus

cd .. can be used to move to previous directory
files can be created using many commands like cat,echo and nano where echo expects the content of the file beforehand

echo "Hello, DevOps World!" > greeting.txt

and nano lets you edit the file in the terminal itself.

Removing files

Often devs like me mess up with project configuration files so irreversibly that its easier to start over rather than trying and fixing the issue.

rm -rf Vueproject/

🧠Explanation:

• Deletes the Vueproject/ directory and all its contents.

• -r: Recursive, -f: Force (no confirmation). Use with caution.

Example: Move all files from source_dir to target_dir

We often need to transfer all the files of code from a directory which was not intended for the project in that case this command comes in very handy

mv source_dir/* target_dir/

🧠What it does:

• mv — move command.

• source_dir/* — selects all files and folders inside source_dir.

• target_dir/ — the directory where you want to move them.

🔹 2. File Permissions & Ownership

Linux uses a permission model that controls who can read, write, or execute files. Let’s explore how to inspect and change those settings.

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Listing files and checking file permissions

ls -laht ~

🧠Explanation:

• ls → List directory contents

• -l → Use a long listing format permission bits (e.g., -rw-r--r--)

• -a → Show hidden files

• -h → Display sizes in human-readable format (e.g., KB, MB)

• -t → Sort by modification time (newest first)

• ~ → Home directory

Changing ownership and setting permissions

You’ve created a directory /opt/devops_logs that should only be accessed by a user named devops_user. No one else should have read or write access

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1️⃣ Create the directory:

sudo mkdir /opt/devops_logs

2️⃣ Change ownership to devops_user:

sudo chown devops_user:devops_user /opt/devops_logs

• chown — changes the owner and group of the directory.

• devops_user:devops_user — sets both the owner and group to devops_user.

• /opt/devops_logs — the target directory.

3️⃣ Restrict access using chmod:

sudo chmod 700 /opt/devops_logs

• chmod 700 — sets permissions to:

  • rwx------ → only the owner can read, write, and execute.

• This prevents all other users from accessing the directory.

🔹 3. Process Management and disk space monitoring

In Linux, processes represent running programs. Understanding how to monitor, prioritize, and control them is crucial for maintaining system health and performance and disk space.

Finding the total disk usage of the /var/log directory in human-readable format.

du -sh /var/log

🧠Explanation:

• du → Disk usage command

• -s → Summarize total size instead of listing all files

• -h → Human-readable format (e.g., KB, MB, GB)

Using top / htop

top is a built-in command-line tool that displays real-time system processes.htop is a more user friendly enhanced version.

Start it:

top|htop

What you'll see:

• CPU usage

• Memory usage

• Running processes

• Process IDs (PID), users, etc.

To find a specific process (e.g., python):

1. Press / → type the process name (e.g., python) → press Enter.

2. It will highlight the matching process.

Kill a Process Manually with kill

kill 1234         # Sends SIGTERM (soft kill)
kill -9 1234      # Sends SIGKILL (force kill)

replace 1234 with process id

🧠Bonus: Find PID with ps + grep

ps aux | grep python

Then use kill or htop as shown.

df – Disk Free Space

Usage:

df -h

Explanation:

• Displays available and used disk space for all mounted filesystems.

• -h makes the output human-readable (e.g., GB, MB).

• Useful to detect disk space issues quickly.

uptime – System Load and Uptime

Usage:

uptime

Explanation:

• Displays how long the system has been running, number of users, and system load averages for 1, 5, and 15 minutes.

• Useful for quick health checks.

vmstat – Virtual Memory Statistics

Usage:

vmstat 2 5

Explanation:

• Reports on memory, swap, I/O, system, and CPU usage.

• The above command prints stats every 2 seconds, 5 times.

• Helps diagnose CPU/memory performance issues.

iostat – I/O Statistics

Usage:

iostat -xz 1

Explanation:

• Reports CPU and device I/O stats.

• -x: Extended statistics

• -z: Suppress devices with no activity

• 1: Update every second

• Excellent for identifying disk bottlenecks.

🔹 4. Package Management (Debian/Ubuntu)

Managing software is one of the most important tasks for a DevOps engineer. Debian-based systems like Ubuntu use apt and dpkg to install, remove, and manage software packages.

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apt remove – Remove Installed Package

Usage:

sudo apt remove nginx

apt purge – Remove Package and Config Files

Usage:

sudo apt purge nginx

apt autoremove – Remove Unused Dependencies

Usage:

sudo apt autoremove

🔹 5. Remote Access & Transfer

DevOps engineers often manage remote servers and need to transfer files securely. These commands are essential for file transfers and interacting with web endpoints from the command line,let’s explore a few.

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wget – Download Files from the Web

wget https://example.com/file.zip

📘 Explanation:

• wget is a non-interactive command-line tool to download files from the internet.

• This command downloads file.zip from the specified URL.

• It works with HTTP, HTTPS, and FTP protocols.

ping – Test Network Connectivity

 ping -c 4 -w 5 google.com

📘 Explanation:

• Sends ICMP echo request packets to a host.

• Helps you test if a server or host is reachable.

• By default, it keeps sending packets until interrupted.

• -c 4: Send only 4 packets.

• -w 5: Ping for 5 seconds.

Using curl:

curl https://example.com

This will print the raw HTML content of the homepage of example.com directly to your terminal.

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That wraps up the Linux Essentials Every DevOps Engineer Needs!

You now have a working knowledge of:

✅ Shell navigation
✅ Filesystem hierarchy
✅ Permissions & ownership
✅ User/group management
✅ Process handling
✅ Monitoring systems
✅ Managing packages
✅ Connecting & transferring remotely

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