Basic Commands

Navigating the CLI

As a DevOps engineer, you will spend most of your time in the Command Line Interface (CLI). Every server you deploy to, every container you manage, every log you tail — it all happens in the terminal. Mastering these core navigation commands is your first step.

In DevOps, you will commonly connect to remote Linux servers via SSH. All commands in this tutorial work on any Linux system — from a local VM to a cloud instance in the cloud.

Where Am I? — `pwd`

The pwd command (Print Working Directory) shows your current location in the filesystem.

$ pwd
/home/admin

Sample Output:

/home/admin

Why it matters in DevOps: When you SSH into a server, you often land in your home directory. Use pwd to confirm where you are before running commands that might affect the wrong location.

What is Here? — `ls`

The ls command lists files and directories.

Basic Listing

$ ls
Documents  Downloads  projects  config.yaml

Long Listing with Details

The -la flags show hidden files and detailed metadata:

Flag	Meaning
`-l`	Long format with permissions, owner, size, date
`-a`	Show hidden files (starting with `.`)

$ ls -la
total 48
drwxr-xr-x  5 admin admin 4096 Apr 10 09:15 .
drwxr-xr-x  3 root root 4096 Apr 10 08:00 ..
-rw-r--r--  1 admin admin  220 Apr  9 15:30 .bashrc
-rw-------  1 admin admin 3154 Apr 10 09:15 .bash_history
drwxr-xr-x  3 admin admin 4096 Apr  9 14:22 .ssh
drwxr-xr-x  3 admin admin 4096 Apr 10 09:00 projects
-rw-r--r--  1 admin admin  894 Apr 10 08:45 config.yaml

Column meanings in long listing:

Column	Example	Meaning
Permissions	`drwxr-xr-x`	Type + read/write/execute for owner/group/other
Hard links	`5`	Number of hard links to this file
Owner	`admin`	Who owns the file
Group	`admin`	Group assigned to the file
Size	`4096`	File size in bytes
Date	`Apr 10 09:15`	Last modification time
Name	`projects`	File or directory name

Useful `ls` Variations for DevOps

# List files sorted by size (largest first) — useful for finding large files
ls -lhS
 
# List files by modification time (newest first) — useful for finding recent changes
ls -lht
 
# Append indicator for file types (/ for directories, * for executables)
ls -laF
 
# Recursive listing — see entire directory tree
ls -laR /var/log

Moving Around — `cd`

The cd command (Change Directory) navigates between folders.

Essential Navigation

# Navigate to a specific path
$ cd /var/log
$ pwd
/var/log
 
# Go up one level
$ cd ..
$ pwd
/var
 
# Go to your home directory immediately
$ cd ~
$ pwd
/home/admin
 
# Go back to previous directory
$ cd -
/var/log

Quick shortcuts:

Shortcut	Meaning
`cd`	Go home
`cd ~`	Go home
`cd -`	Go to previous directory
`cd ..`	Go up one level
`cd ../..`	Go up two levels

In Bash, . means "current directory" and .. means "parent directory". These are relative to your current position.

File and Folder Operations

Create a File — `touch`

Creates an empty file or updates timestamp of existing file.

$ touch newfile.txt
$ ls -la newfile.txt
-rw-r--r-- 1 admin admin    0 Apr 10 10:30 newfile.txt

DevOps use case: Touch is useful for creating placeholder config files or marker files for deployment scripts.

Create a Directory — `mkdir`

# Create a single directory
$ mkdir configs
 
# Create nested directories (-p is essential for production scripts)
$ mkdir -p /tmp/app/deploy/logs/$(date +%Y%m%d)
$ ls -la /tmp/app/deploy/logs/
total 8
drwxr-xr-x  3 root root 4096 Apr 10 10:30 .
drwxr-xr-x  3 root root 4096 Apr  9 14:00 ..
drwxr-xr-x  3 root root 4096 Apr 10 10:30 20260410

The -p flag is critical — without it, mkdir fails if parent directories don't exist.

Copy a File — `cp`

# Backup a config file
$ cp config.yaml config.yaml.bak
$ ls -la config.yaml*
-rw-r--r-- 1 admin admin  894 Apr 10 08:45 config.yaml
-rw-r--r--  1 admin admin  894 Apr 10 10:35 config.yaml.bak

Useful flags:

Flag	Meaning
`-r`	Copy directories recursively
`-p`	Preserve file attributes (permissions, timestamps)
`-v`	Verbose — show what is being copied

# Copy directory with preserved permissions
cp -rp /etc/nginx /tmp/nginx-backup

Move or Rename — `mv`

# Rename a file
$ mv oldname.txt newname.txt
 
# Move a file to another directory
$ mv report.pdf /home/admin/Documents/
 
# Move with verification
$ mv -v site.conf /etc/nginx/site.conf
renamed 'site.conf' -> '/etc/nginx/site.conf'

Remove — `rm`

# Remove a single file
$ rm oldfile.txt
 
# Remove with confirmation
$ rm -i config.yaml
rm: remove regular file 'config.yaml'? y
 
# Recursively remove a directory and all contents
$ rm -rf /tmp/deploy-archive

There is no "Trash Bin" or "Recycle Bin" in the Linux CLI. When you run rm -rf, the files are permanently deleted instantly. There is no undo. Always double-check your path before executing.

Safe practice: Use rm -i for interactive deletion or test your path with ls first:

# Verify what you are about to delete
$ ls /tmp/old-deploy
total 48
drwxr-xr-x  3 admin admin 4096 Apr 10 09:00 .
drwxr-xr-x  3 root root 4096 Apr 10 08:00 ..
-rw-r--r--  1 admin admin 1024 Apr 10 09:00 app.log
-rw-r--r--  1 admin admin 2048 Apr 10 09:00 deploy.sh
 
# Now delete with confidence
$ rm -rf /tmp/old-deploy

Quick Reference Card

Task	Command
Show current directory	`pwd`
List files	`ls`
List with details	`ls -la`
List hidden files	`ls -a`
Change directory	`cd /path`
Go home	`cd ~`
Go up one level	`cd ..`
Go to previous dir	`cd -`
Create empty file	`touch file.txt`
Create directory	`mkdir dir`
Create nested dirs	`mkdir -p path/to/deep/dir`
Copy file	`cp src dst`
Copy directory	`cp -r src dst`
Move/Rename	`mv src dst`
Remove file	`rm file.txt`
Remove directory	`rm -rf dir`

Practice Challenge

Try these on a Linux system to build muscle memory:

Navigate to /tmp and create a directory structure: projects/app/backend/logs
Create a file README.md in the backend directory
Copy the README to README.bak
List all files including hidden ones
Remove the backup file and the entire directory structure you just created

Once comfortable with these commands, you are ready to move on to File Permissions and Text Processing — the two skills that separate basic users from effective DevOps engineers.

Navigating the CLI

Where Am I? — pwd

What is Here? — ls

Basic Listing

Long Listing with Details

Useful ls Variations for DevOps

Moving Around — cd