Advanced Linux Commands

This guide covers advanced usage of common Linux commands with practical examples.

ls - List Directory Contents

Explore the Linux ls command and its practical applications for managing files and directories. Learn how to utilize various options to retrieve detailed file information and navigate directory structures effectively.

Demos

1. Basic Usage List files and folders in the current directory.

ls

Output:

file1.txt  file2.txt  folder1  folder2

2. Long Format Listing Provides detailed information including permissions, owner, size, and modification date.

ls -l

Output:

total 8
-rw-r--r-- 1 labex labex 0 Apr 12 12:34 file1.txt
-rw-r--r-- 1 labex labex 0 Apr 12 12:34 file2.txt
drwxr-xr-x 2 labex labex 4096 Apr 12 12:34 folder1
drwxr-xr-x 2 labex labex 4096 Apr 12 12:34 folder2

---

cd - Change Directory

Explore the Linux cd command, learn how to navigate the file system, and understand the difference between relative and absolute paths.

Demos

1. Absolute Path Navigate to a specific directory using its full path.

cd /home/labex/project

Output:

labex@ubuntu:/home/labex/project$

2. Parent Directory Navigate up one level to the parent directory.

cd ..

Output:

labex@ubuntu:/home/labex$

---

pwd - Print Working Directory

Explore the Linux pwd command, its purpose, and practical examples of using it with other commands to manage files and directories.

Demos

1. Basic Usage Display the current working directory.

pwd

Output:

/home/labex/project

2. In Subdirectory Show path when inside a subdirectory.

pwd

Output:

/home/labex/project/subdirectory

---

cat - Concatenate Files

Connects and prints the content of files to standard output.

Demos

1. Display File Content View the contents of a text file.

cat filename.txt

Output:

This is the content of the file.

2. Create File Create a new file and add content (press Ctrl+D to save).

cat > newfile.txt

---

echo - Display Line of Text

Displays a line of text or variable value to standard output.

Demos

1. Print Text Print a simple string to the terminal.

echo "Hello World"

Output:

Hello World

---

touch - Change File Timestamps

Update the access and modification times of a file, or create an empty file if it doesn't exist.

Demos

1. Create Empty File Create a new empty file.

touch newfile.txt

---

mkdir - Make Directories

Create new directories.

Demos

1. Create Directory Create a single directory.

mkdir myfolder

2. Create Nested Directories Create a directory structure with parent directories.

mkdir -p parent/child/grandchild

---

rm - Remove Files or Directories

Remove files or directories. Use with caution.

Demos

1. Remove File Delete a specific file.

rm file.txt

2. Remove Directory Recursive Delete a directory and its contents.

rm -rf directory_name

---

rmdir - Remove Empty Directories

Remove empty directories.

Demos

1. Remove Directory Delete an empty directory.

rmdir empty_folder

---

cp - Copy Files

Copy files and directories.

Demos

1. Copy File Copy a file to a new location.

cp source.txt destination.txt

2. Copy Directory Copy a directory recursively.

cp -r source_dir destination_dir

---

mv - Move or Rename Files

Move or rename files and directories.

Demos

1. Rename File Rename a file in place.

mv oldname.txt newname.txt

2. Move File Move a file to a different directory.

mv file.txt /path/to/directory/

---

head - Output First Part of File

Output the first part of files.

Demos

1. First 10 Lines Display the first 10 lines (default).

head file.txt

2. First N Lines Display the first 5 lines.

head -n 5 file.txt

---

tail - Output Last Part of File

Output the last part of files.

Demos

1. Last 10 Lines Display the last 10 lines (default).

tail file.txt

2. Follow File Output appended data as the file grows (useful for logs).

tail -f access.log

---

wc - Word, Line, Character Count

Print newline, word, and byte counts for each file.

Demos

1. Count Lines Count the number of lines in a file.

wc -l file.txt

Output:

125 file.txt

---

grep - Print Lines Matching a Pattern

Search for specific patterns within files.

Demos

1. Basic Search Search for a string in a file.

grep "error" log.txt

2. Case Insensitive Search without regarding case.

grep -i "error" log.txt

---

sort - Sort Lines of Text Files

Sort lines of text files.

Demos

1. Alphabetical Sort Sort lines alphabetically.

sort names.txt

2. Numeric Sort Sort lines numerically.

sort -n numbers.txt

---

uniq - Report or Omit Repeated Lines

Filter adjacent matching lines.

Demos

1. Remove Duplicates Remove consecutive duplicate lines.

sort file.txt | uniq

2. Count Occurrences Count the number of occurrences of each line.

sort file.txt | uniq -c

---

rev - Reverse Lines

Reverse lines characterwise.

Demos

1. Reverse String Reverse the characters in each line.

echo "Hello" | rev

Output:

olleH

---

base64 - Base64 Encode/Decode

Base64 encode or decode data.

Demos

1. Encode Encode a string.

echo "Linux" | base64

Output:

TGludXgK

2. Decode Decode a base64 string.

echo "TGludXgK" | base64 -d

Output:

Linux

---

strings - Print Printable Characters

Print the sequences of printable characters in files.

Demos

1. Extract Strings Find readable strings in a binary file.

strings /bin/ls | head

---

xxd - Make a Hex Dump

Make a hexdump or do the reverse.

Demos

1. Hex Dump Create a hex dump of a file.

xxd file.txt

---

file - Determine File Type

Determine the type of a file.

Demos

1. Check File Type Identify the type of data in a file.

file image.png

Output:

image.png: PNG image data, 800 x 600, 8-bit/color RGBA, non-interlaced

---

stat - Display File Status

Display detailed file or file system status.

Demos

1. File Info Show detailed statistics about a file.

stat file.txt

---

find - Search for Files

Search for files in a directory hierarchy.

Demos

1. Find by Name Find files with a specific name.

find . -name "*.txt"

2. Find by Size Find files larger than 10MB.

find /var/log -size +10M

---

tree - List Contents in Tree

List directory contents in a tree-like format.

Demos

1. Show Tree Display directory structure.

tree

---

du - Disk Usage

Estimate file space usage.

Demos

1. Directory Size Show size of current directory in human-readable format.

du -sh .

---

which - Locate a Command

Locate a command.

Demos

1. Find Executable Show the full path of a shell command.

which python3

Output:

/usr/bin/python3

---

whereis - Locate Binary, Source, and Manual

Locate the binary, source, and manual page files for a command.

Demos

1. Locate Command Info Find binary and man pages.

whereis ls

---

type - Describe a Command

Display information about command type.

Demos

1. Check Command See if a command is a built-in, alias, or executable.

type cd

Output:

cd is a shell builtin

---

display - Display Image (ImageMagick)

Display an image or image sequence.

Demos

1. Open Image Open an image file in a GUI window.

display image.png

---

evince - Document Viewer

View PDF, PostScript, chemical, DJVU, DVI and TIFF documents.

Demos

1. Open PDF Open a PDF file.

evince document.pdf

---

uname - Print System Information

Print system information.

Demos

1. Kernel Info Print all system information.

uname -a

---

hostname - Show/Set System Name

Show or set the system's host name.

Demos

1. Show Hostname Display the current hostname.

hostname

---

id - Print User and Group IDs

Print user and group IDs.

Demos

1. User Info Show user ID, group ID, and groups.

id

---

uptime - Tell How Long System Has Been Running

Tell how long the system has been running.

Demos

1. Show Uptime Display system uptime and load average.

uptime

---

date - Print or Set System Date and Time

Print or set the system date and time.

Demos

1. Show Date Display current date and time.

date

---

cal - Display a Calendar

Display a calendar.

Demos

1. Current Month Show calendar for current month.

cal

---

df - Report File System Disk Space Usage

Report file system disk space usage.

Demos

1. Disk Space Show disk usage in human-readable format.

df -h

---

free - Display Amount of Free and Used Memory

Display amount of free and used memory in the system.

Demos

1. Memory Usage Show memory usage in standard format.

free -h

---

ps - Report a Snapshot of the Current Processes

Report a snapshot of the current processes.

Demos

1. Active Processes Show all running processes.

ps aux

---

env - Run a Program in a Modified Environment

Run a program in a modified environment or print environment variables.

Demos

1. Print Env Display all environment variables.

env

---

neofetch - System Information Tool

A command-line system information tool written in bash 3.2+.

Demos

1. Show Info Display system info with logo.

neofetch

---

dmesg - Print or Control the Kernel Ring Buffer

Print or control the kernel ring buffer.

Demos

1. Kernel Logs Show kernel messages.

dmesg | tail

---

lsblk - List Block Devices

List information about all available or the specified block devices.

Demos

1. List Devices Show all block devices.

lsblk

---

tty - Print File Name of Terminal Connected to Standard Input

Print the file name of the terminal connected to standard input.

Demos

1. Check TTY Display current terminal name.

tty

---

w - Show Who Is Logged On and What They Are Doing

Show who is logged on and what they are doing.

Demos

1. User Activity Detailed info about currently logged-in users.

w

---

who - Show Who Is Logged On

Show who is logged on.

Demos

1. Users List currently logged-in users.

who

---

arch - Print Machine Architecture

Print machine architecture.

Demos

1. Architecture Show system architecture (e.g., x86_64).

arch

---

nproc - Print Number of Processing Units

Print the number of processing units available.

Demos

1. CPU Count Show number of CPU cores.

nproc

---

ping - Send ICMP ECHO_REQUEST to Network Hosts

Send ICMP ECHO_REQUEST to network hosts.

Demos

1. Ping Host Check connectivity to a host.

ping google.com

2. Limit Count Send only 4 packets.

ping -c 4 google.com

---

ifconfig - Configure a Network Interface

Configure a network interface.

Demos

1. Show Interfaces Display all network interfaces.

ifconfig

---

netstat - Print Network Connections

Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships.

Demos

1. Listening Ports Show all listening ports.

netstat -tuln

---

ss - Another Utility to Investigate Sockets

Another utility to investigate sockets.

Demos

1. All Sockets Display all TCP/UDP sockets.

ss -tuln

---

nslookup - Query Internet Name Servers

Query Internet name servers interactively.

Demos

1. Lookup Domain Find IP address of a domain.

nslookup google.com

---

traceroute - Print the Route Packets Trace to Network Host

Print the route packets trace to network host.

Demos

1. Trace Route Show path to a host.

traceroute google.com

---

dig - DNS Lookup Utility

DNS lookup utility.

Demos

1. DNS Query Perform a DNS lookup.

dig google.com

---

clear - Clear the Terminal Screen

Clear the terminal screen.

Demos

1. Clear Screen Clear the text from the terminal window.

clear

---

history - Display Command History

Display or manipulate the history list.

Demos

1. Show History List previously executed commands.

history

---

man - Interface to the System Reference Manuals

Interface to the system reference manuals.

Demos

1. Manual Page Read the manual for a command.

man ls

---

alias - Define or Display Aliases

Define or display aliases.

Demos

1. Create Alias Create a shortcut for a command.

alias ll='ls -l'

---

expr - Evaluate Expressions

Evaluate expressions.

Demos

1. Math Perform integer arithmetic.

expr 10 + 20

Output:

30

---

seq - Print a Sequence of Numbers

Print a sequence of numbers.

Demos

1. Sequence Print numbers from 1 to 5.

seq 1 5

Output:

1
2
3
4
5

---

factor - Print Prime Factors

Print prime factors.

Demos

1. Factorize Find prime factors of a number.

factor 100

Output:

100: 2 2 5 5

---

sleep - Delay for a Specified Amount of Time

Delay for a specified amount of time.

Demos

1. Pause Pause execution for 5 seconds.

sleep 5

---

bc - An Arbitrary Precision Calculator Language

An arbitrary precision calculator language.

Demos

1. Calculation Perform calculation.

echo "10 + 20" | bc

Output:

30

---

exit - Cause the Shell to Exit

Cause the shell to exit.

Demos

1. Close Shell Exit the current terminal session.

exit

---

logout - Exit a Login Shell

Exit a login shell.

Demos

1. Logout Log out of the current session.

logout

---

poweroff - Power Off the System

Power off the system.

Demos

1. Shutdown Turn off the computer immediately.

poweroff

---

reboot - Reboot the System

Reboot the system.

Demos

1. Restart Restart the computer immediately.

reboot

---

halt - Stop the System

Stop the system.

Demos

1. Stop Halt the system immediately.

halt

---

reset - Reset Terminal

Reset terminal.

Demos

1. Reset Reset terminal settings.

reset

---

cowsay - Configurable Speaking Cow

Configurable speaking cow.

Demos

1. Say Hello Make the cow say something.

cowsay "Hello Linux"

Output:

 _____________
< Hello Linux >
 -------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

---

fortune - Print a Random, Hopefully Interesting, Adage

Print a random, hopefully interesting, adage.

Demos

1. Tell Fortune Display a random quote.

fortune

---

cmatrix - Terminal Matrix Rain

Terminal Matrix rain.

Demos

1. Start Matrix Show the scrolling Matrix effect.

cmatrix

---

sl - Steam Locomotive

Steam Locomotive.

Demos

1. Run Train Show an animation of a steam locomotive (often run by typo when meaning ls).

sl

---

figlet - Display Large Characters

Display large characters.

Demos

1. Banner Create a text banner.

figlet Linux

Output:

 _     _
| |   (_)_ __  _   ___  __
| |   | | '_ \| | | \ \/ /
| |___| | | | | |_| |>  <
|_____|_|_| |_|\__,_/_/\_\