Beginner’s Guide to Linux Basic Commands for DevOps

 

When you step into the world of DevOps, cloud computing, or software development, the graphical user interface (GUI) takes a backseat. The terminal becomes your primary steering wheel, and Linux commands are the fuel.

Navigating a terminal can feel like learning a foreign language at first, but it boils down to a core set of foundational commands. Let's break down the essential Linux commands you need to master, grouped by what they actually do.

1. Navigation & File Management

pwd (Print Working Directory)

Shows you exactly which folder you are currently standing in.

$ pwd
/home/ubuntu/devops_project

ls (List)

Lists files and folders. Use -la to show detailed information and hidden files (files starting with a dot).

# Basic list
$ ls
app.py  config.ini  logs

# Detailed list (shows permissions, size, owner)
$ ls -la
drwxr-xr-x  3 ubuntu ubuntu 4096 Jul 16 10:00 .
-rw-r--r--  1 ubuntu ubuntu  245 Jul 16 10:05 app.py
-rw-r--r--  1 ubuntu ubuntu 1024 Jul 16 10:02 .env

cd (Change Directory)

Moves you around the file system.

# Move into a folder
$ cd logs

# Move up one level (backwards)
$ cd ..

# Jump straight to your user's home directory
$ cd ~

mkdir (Make Directory)

Creates a new folder. Use -p to create nested parent folders at once.

# Create a single folder
$ mkdir scripts

# Create nested folders (e.g., source/assets/images)
$ mkdir -p src/assets/images

rm (Remove)

Deletes files or directories. Be careful: Linux doesn't have a recycle bin!

# Delete a single file
$ rm temp.log

# Force delete an entire folder and everything inside it safely (-r recursive, -f force)
$ rm -rf old_project/

cp (Copy)

Copies files or directories. Use -r to copy folders.

# Copy a file and give it a new name
$ cp config.yaml config.yaml.bak

# Copy an entire folder to a backup destination
$ cp -r src/ src_backup/

mv (Move / Rename)

Moves a file to another location, or renames it if kept in the same folder.

# Rename a file
$ mv deployment.txt live-deployment.yaml

# Move a file into a specific directory
$ mv script.sh scripts/

2. Reading & Inspecting Files

cat (Concatenate)

Dumps the entire content of a file into the terminal screen.

$ cat version.txt
v2.4.1-build-882

less

Opens large files interactively without breaking your terminal page or clogging system memory.

$ less system.log
# [Opens an interactive view. Press the Arrow keys to scroll up/down, press 'q' to exit]

head

Shows the very top (first 10 lines) of a file.

$ head configuration.conf
# Displaying the first 10 lines of the file...
server {
    listen 80;
    server_name localhost;

tail

Shows the bottom (last 10 lines) of a file. Use -f to watch logs update in real time.

# Show last 10 lines
$ tail application.log

# Live stream incoming logs (ideal for debugging running applications)
$ tail -f application.log

3. Finding Files & Binaries

find

Walks through directories to find specific files based on criteria like names or extensions

# Search for all files ending in ".json" inside the current folder (".")
$ find . -name "*.json"
./package.json
./config/settings.json

locate

Finds files instantly using a pre-indexed background database (much faster than find).

$ locate nginx.conf
/etc/nginx/nginx.conf
/usr/share/doc/nginx/nginx.conf

which

Tells you the exact system path of an executable/binary program you are running.

$ which docker
/usr/bin/docker

4. Text Processing & Data Manipulation

grep (Global Regular Expression Print)

Searches for a specific word or pattern inside a text stream or file.

# Find all lines containing the word "CRITICAL" inside an application log
$ grep "CRITICAL" application.log
2026-07-16 12:00:05 [CRITICAL] Database connection lost!

awk

Slices structured text outputs into columns. By default, it uses spaces to separate columns.

# Imagine running a command that outputs columns, and you only want the 2nd column ($2)
$ echo "John 25 Engineer" | awk '{print $2}'
25

sed (Stream Editor)

Finds and replaces text inside a file instantly without opening an editor.

# Replace "localhost" with "10.0.0.5" inside settings.txt
$ sed -i 's/localhost/10.0.0.5/g' settings.txt

sort & uniq

sort arranges lines alphabetically/numerically. uniq filters out identical consecutive lines. They are almost always used together.

# Suppose names.txt contains: Charlie, Alpha, Charlie
$ sort names.txt
Alpha
Charlie
Charlie

# Sort them and extract only the unique values
$ sort names.txt | uniq
Alpha
Charlie

cut

Slices out specific parts of lines based on a delimiter character.

# Split by a hyphen (-) delimiter (-d) and take the first field (-f1)
$ echo "prod-web-server-01" | cut -d'-' -f1
prod

xargs

Takes the output of a command and loops it into another command as arguments.

# Find all files ending in ".tmp" and delete them using xargs
$ find . -name "*.tmp" | xargs rm