Linux commands form the backbone of using and managing a Linux system. This guide covers the most essential commands every Linux user should know.

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1. File and Directory Management

List Files and Directories

ls
Options:

• ls -l for detailed listing.
• ls -a to include hidden files.

Change Directory

cd
Use cd .. to move up one level.

Print Current Directory

pwd

Create a Directory

mkdir

Remove a Directory

rmdir
Use rm -r <directory_name> for non-empty directories.

Copy Files or Directories

cp
Use cp -r for directories.

Move or Rename Files

mv

Delete Files

rm

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2. File Viewing and Editing

View File Content

cat
Use tac <file_name> to display content in reverse.

Display File Content Page-by-Page

less

Display First or Last Lines of a File

head
tail

Edit Files

nano
Use vi <file_name> or vim <file_name> for advanced editing.

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3. File Permissions and Ownership

View File Permissions

ls -l

Change Permissions

chmod
Examples:

• chmod 755 <file_name>
• chmod +x <file_name> to make a file executable.

Change Ownership

chown :

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4. Process Management

View Running Processes

ps aux
Use top or htop for an interactive process viewer.

Kill a Process

kill
Use kill -9 <process_id> for a forced termination.

Check System Resource Usage

free -h for memory usage.
df -h for disk usage.

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5. Networking Commands

Check Network Interfaces and IP Address

ip a
Use ifconfig if ip is unavailable.

Test Network Connectivity

ping

Download Files from the Internet

wget
curl -O

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6. Search and Find Commands

Search for Files

find -name

Search Inside Files

grep
Use grep -r <pattern> <directory> for recursive searches.

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7. User Management

Add a New User

sudo adduser

Switch Users

su

Check Current User

whoami

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8. System Monitoring

Display System Uptime

uptime

View System Logs

journalctl
Use dmesg for kernel logs.

Check Disk Space Usage

df -h

Check Inode Usage

df -i

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9. Archiving and Compression

Create a Tar Archive

tar -cvf .tar

Extract a Tar Archive

tar -xvf .tar

Compress Files with Gzip

gzip

Decompress Gzip Files

gunzip .gz

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10. Package Management

Debian/Ubuntu-Based Systems

sudo apt-get update
sudo apt-get install

Red Hat/CentOS-Based Systems

sudo yum update
sudo yum install

Arch-Based Systems

sudo pacman -Syu
sudo pacman -S

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Learning these commands will help you become proficient in navigating and managing a Linux system.
Use the man command (e.g., man ls) for detailed information about any command.