Linux Commands Tutorial

What it does

Lists files and directories. Use -l for detailed view, -a for hidden files, -h for readable sizes.

Output

drwxr-xr-x 5 user group 4.0K Jan 11 15:00 Documents
-rw-r--r-- 1 user group  2.1M Jan 11 14:30 report.pdf

What it does

Changes directory. Use .. for parent, ~ for home, - for previous directory.

Output

(changes directory)

What it does

Prints current working directory path.

Output

/home/user/projects/my-app

What it does

Creates new directories. Use -p to create parent directories.

Output

(creates directories)

What it does

Removes files/directories. Use -r for recursive, -f to force. BE CAREFUL!

Output

(removes files)

What it does

Copies files/directories. Use -r for directories, -i for interactive.

Output

(copies files)

What it does

Moves or renames files and directories.

Output

(renames file)

What it does

Creates empty files or updates timestamps.

Output

(creates files)

What it does

Displays file contents. Can concatenate multiple files.

Output

{
  "port": 3000,
  "host": "localhost"
}

What it does

Views files page by page. Space to scroll, q to quit.

Output

(opens interactive viewer)

What it does

Shows first N lines of file (default 10).

Output

[2026-01-11] ERROR: Connection failed
[2026-01-11] ERROR: Timeout

What it does

Shows last N lines. Use -f to follow updates in real-time.

Output

192.168.1.1 - "GET /api HTTP/1.1" 200

What it does

Creates links. Use -s for symbolic (soft) links.

Output

(creates symbolic link)

What it does

Determines file type based on content.

Output

archive.tar.gz: gzip compressed data

What it does

Displays detailed file/filesystem status.

Output

Size: 1024	Blocks: 8
Access: 2026-01-11 15:30:00

What it does

Displays directory structure as tree. Install separately.

Output

.
├── src
│   ├── components
│   └── utils
└── package.json

What it does

Extracts filename from path.

Output

file.txt

What it does

Extracts directory path from full path.

Output

/path/to

What it does

Shows target of symbolic link.

Output

/usr/bin/python3.10

What it does

Resolves absolute path of file.

Output

/home/user/file.txt

What it does

Prints system information. Use -a for all details.

Output

Linux server 5.15.0-91-generic x86_64 GNU/Linux

What it does

Shows current username.

Output

ubuntu

What it does

Shows or sets system hostname. Use -I for IPs.

Output

web-server-01

What it does

Shows system uptime and load averages.

Output

15:30:12 up 7 days, 3:42, 2 users, load: 0.45, 0.38, 0.32

What it does

Shows/sets date and time. Supports custom formatting.

Output

2026-01-11 15:30:45

What it does

Shows memory usage. Use -h for human-readable.

Output

Mem:   7.8Gi   2.1Gi   3.2Gi

What it does

Shows command history. Use !number to re-execute.

Output

1001  cd /var/www
1002  ls -la
1003  vim index.html

What it does

Displays manual pages for commands.

Output

(opens manual page)

What it does

Prints text. Use > to write, >> to append to files.

Output

Hello World

What it does

Creates command shortcuts. Add to ~/.bashrc for permanent.

Output

(creates alias)

What it does

Shows environment variables.

Output

PATH=/usr/local/bin:/usr/bin:/bin

What it does

Sets environment variables.

Output

(sets variable)

What it does

Shuts down system. Use -h for halt, -r for reboot.

Output

(system shutting down)

What it does

Reboots the system immediately.

Output

(system rebooting)

What it does

Manages systemd services. start/stop/restart/status.

Output

● nginx.service - running

What it does

Lists running processes. Use aux for all processes.

Output

www-data  1234  0.0  0.5  nginx: master

What it does

Real-time process viewer. Press q to quit.

Output

(interactive display)

What it does

Enhanced top with colors. Must install separately.

Output

(colorful interactive display)

What it does

Terminates process by PID. Use -9 for force kill.

Output

(terminates process)

What it does

Kills all processes by name.

Output

(terminates all node processes)

What it does

Signals processes by pattern.

Output

(terminates matching processes)

What it does

Finds process IDs by name pattern.

Output

1234
1235
1236

What it does

Puts suspended job in background.

Output

[1]+ running	sleep 100 &

What it does

Brings background job to foreground.

Output

sleep 100

What it does

Lists active background jobs.

Output

[1]+ Running	sleep 100 &

What it does

Runs command immune to hangups, with output to nohup.out.

Output

nohup: ignoring input and appending output

What it does

Executes command periodically and displays output.

Output

(refreshes every 1 second)

What it does

Tests network connectivity. Use -c for count.

Output

64 bytes from 142.250.185.46: time=12.4 ms
4 packets, 0% loss

What it does

Transfers data from/to servers. Use -I for headers.

Output

HTTP/2 200
server: GitHub.com

What it does

Downloads files from web. Supports resume.

Output

file.zip saved [45234/45234]

What it does

Securely connects to remote servers.

Output

user@192.168.1.100's password:

What it does

Securely copies files over SSH. Use -r for directories.

Output

file.txt  100%  1024KB/s

What it does

Syncs files efficiently. Only transfers differences.

Output

sent 1,234 bytes  received 56 bytes

What it does

Modern network configuration tool. Replaces ifconfig.

Output

inet 192.168.1.100/24 brd 192.168.1.255

What it does

Legacy network interface configuration tool.

Output

inet 192.168.1.100  netmask 255.255.255.0

What it does

Shows network connections and statistics.

Output

tcp 0 0.0.0.0:80 LISTEN 1234/nginx

What it does

Modern replacement for netstat. Faster.

Output

tcp   LISTEN  0.0.0.0:80

What it does

DNS lookup utility with detailed output.

Output

;; ANSWER SECTION:
google.com. 142.250.185.46

What it does

Queries DNS servers interactively.

Output

Address: 142.250.185.46

What it does

Traces packet route to network host.

Output

1  192.168.1.1  1.234 ms
2  10.0.0.1  5.678 ms

What it does

Netcat - arbitrary TCP/UDP connections.

Output

Connection to 127.0.0.1 80 port succeeded!

What it does

Shows or sets system hostname.

Output

192.168.1.100 172.17.0.1

What it does

Views/modifies ARP cache (IP-MAC mappings).

Output

192.168.1.1 at aa:bb:cc:dd:ee:ff

What it does

Changes file permissions. Read=4, Write=2, Execute=1.

Output

(changes permissions)

What it does

Changes file owner and group.

Output

(changes ownership)

What it does

Changes group ownership only.

Output

(changes group)

What it does

Sets default file creation permissions mask.

Output

(sets umask)

What it does

Executes command as superuser. Requires password.

Output

[sudo] password:
Hit:1 http://archive.ubuntu.com

What it does

Switches user. Use - for login shell.

Output

Password:

What it does

Changes user password.

Output

Enter new password:
passwd: password updated

What it does

Searches for patterns. Use -r for recursive, -i for case-insensitive.

Output

/var/log/app.log:42: ERROR: Database failed

What it does

Searches files by name, type, size, permissions, etc.

Output

/home/user/app.log
/home/user/error.log

What it does

Finds files by name using database. Very fast.

Output

/etc/nginx/nginx.conf

What it does

Locates command executable path.

Output

/usr/bin/python3

What it does

Locates binary, source, and manual pages.

Output

ls: /bin/ls /usr/share/man/man1/ls.1.gz

What it does

Stream editor for text transformation.

Output

(shows file with old→new)

What it does

Pattern scanning and text processing language.

Output

john 25
mary 30

What it does

Sorts lines. Use -n for numeric, -r for reverse.

Output

1
5
10
23
100

What it does

Removes duplicate adjacent lines. Often used after sort.

Output

(unique lines only)

What it does

Extracts sections from lines. Great for CSV.

Output

name
john
mary

What it does

Counts lines, words, bytes. Use -l for lines only.

Output

1247 app.log

What it does

Compares files line by line.

Output

< old line
> new line

What it does

Translates or deletes characters.

Output

HELLO

What it does

Formats input into columns.

Output

name  age  city
john  25   NY

What it does

Reads stdin and writes to stdout AND files.

Output

log
(also appends to log.txt)

What it does

Archives files. -c create, -x extract, -z gzip, -v verbose.

Output

(creates archive)

What it does

Compresses files using gzip algorithm.

Output

(creates largefile.txt.gz)

What it does

Decompresses gzip files.

Output

(extracts to file.txt)

What it does

Compresses to ZIP format. Use -r for directories.

Output

adding: project/index.js (deflated 65%)

What it does

Extracts ZIP archives. Use -l to list contents.

Output

inflating: file1.txt
inflating: file2.txt

What it does

Compresses using bzip2 (better compression than gzip).

Output

(creates largefile.txt.bz2)

What it does

Compresses using LZMA (best compression).

Output

(creates largefile.txt.xz)

What it does

7-Zip archiver with high compression. Install separately.

Output

Everything is Ok

What it does

Shows disk space usage for filesystems. Use -h for readable.

Output

Filesystem   Size  Used Avail Use%
/dev/sda1     50G   35G   13G  74%

What it does

Estimates file/directory space usage.

Output

2.3G    /var/log

What it does

Partition table manipulator. Use -l to list.

Output

Disk /dev/sda: 50 GiB

What it does

Mounts filesystems.

Output

(mounts device)

What it does

Unmounts filesystems.

Output

(unmounts device)

What it does

Lists block devices (disks, partitions).

Output

sda      8:0    0   50G  0 disk
├─sda1   8:1    0   49G  0 part /

What it does

Shows block device attributes (UUID, type).

Output

/dev/sda1: UUID="abc-123" TYPE="ext4"

What it does

Creates new user. Use -m for home dir, -s for shell.

Output

(creates user)

What it does

Modifies user account. Use -aG to add to groups.

Output

(adds user to docker group)

What it does

Deletes user. Use -r to remove home directory.

Output

(deletes user and home)

What it does

Creates new group.

Output

(creates group)

What it does

Deletes group.

Output

(deletes group)

What it does

Prints user and group IDs.

Output

uid=1001(john) gid=1001(john) groups=1001(john),27(sudo)

What it does

Shows last logged in users.

Output

john  pts/0  192.168.1.50  Sat Jan 11 14:30 - 15:00

What it does

Debian package manager. update/install/remove packages.

Output

Reading package lists... Done
Upgrading 42 packages

What it does

Older Debian package manager. Still widely used.

Output

Setting up nginx...
Done.

What it does

Searches apt package database.

Output

python3 - Interactive high-level language

What it does

Low-level Debian package tool.

Output

ii  nginx  1.18.0  high performance web server

What it does

Red Hat package manager.

Output

Installing nginx...
Complete!

What it does

Modern Red Hat package manager (replaces yum).

Output

Installing nginx...
Complete!

What it does

Universal Linux package manager.

Output

code installed

What it does

Cross-distro app distribution system.

Output

Installing GIMP...
Done.