LWM-Linux/01 - Introduction to Linux/Basic Linux Commands.md

Basic Linux Commands

1. Navigation and File Management:

a) pwd (Print Working Directory)

• Shows the current directory path
• Usage: pwd

b) ls (List)

• Lists files and directories in the current directory
• Usage: ls [options] [directory]

Common options:

• l: Long format with details
• a: Show hidden files
• h: Human-readable file sizes

c) cd (Change Directory)

• Changes the current directory
• Usage:
• cd [directory]

d) mkdir (Make Directory)

• Creates a new directory
• Usage: mkdir [directory_name]

e) rmdir (Remove Directory)

• Removes an empty directory
• Usage: rmdir [directory_name]

f) touch

• Creates an empty file or updates timestamps
• Usage: touch [filename]

g) cp (Copy)

• Copies files or directories
• Usage: cp [source] [destination]

Common Options:

 -r: Recursive (for directories)

h) mv (Move)

• Moves or renames files and directories
• Usage: mv [source] [destination]

i) rm (Remove)

• Deletes files or directories
• Usage: rm [options] [file/directory]

Options:

 -r: Recursive (for directories)
 -f: Force deletion without prompting

2. File Viewing and Editing:

a) cat (Concatenate)

• Displays file contents
• Usage: cat [filename]

b) less

• Views file contents page by page
• Usage: less [filename]

c) head

• Displays the first few lines of a file
• Usage: head [options] [filename]

Common Options:

 -n [number]: Specify number of lines

d) tail

• Displays the last few lines of a file
• Usage: tail [options] [filename]

Common Options:

 -n [number]: Specify number of lines
 -f: Follow file updates in real-time

e) nano

• Simple text editor
• Usage: nano [filename]

3. File Permissions and Ownership:

a) chmod (Change Mode)

• Modifies file permissions
• Usage: chmod [options] [mode] [file/directory]

b) chown (Change Owner)

• Changes file ownership
• Usage: chown [user]:[group] [file/directory]

4. System Information:

a) uname

• Displays system information
• Usage: uname [options]

Common Options:

 -a: All information

b) df (Disk Free)

• Shows disk space usage
• Usage: df [options]

Common Options:

 -h: Human-readable sizes

c) du (Disk Usage)

• Estimates file and directory space usage
• Usage: du [options] [directory]

Common Options:

 -h: Human-readable sizes
 -s: Summary for directory

5. Process Management:

a) ps (Process Status)

• Lists running processes
• Usage: ps [options]

Common options:

 -aux: Detailed information for all processes

b) top

• Displays real-time system process information
• Usage: top -u [user]

Common Options:

 -u: active apps for specified user

c) kill

• Terminates processes
• Usage: kill [options] [PID]

Common Options:

 -9: Force kill

6. Network Commands:

a) ping

• Tests network connectivity
• Usage: ping [options] [destination]

b) ifconfig

• Displays network interface information
• Usage: ifconfig

c) ssh (Secure Shell)

• Connects to remote systems securely
• Usage: ssh [user]@[host]

Common Options:

 -p: Specify a port

7. Package Management (for Debian-based systems):

a) apt-get update

• Updates package lists
• Usage: sudo apt-get update

b) apt-get upgrade

• Upgrades installed packages
• Usage: sudo apt-get upgrade

c) apt-get install

• Installs new packages
• Usage: sudo apt-get install [package_name]

8. File Compression:

a) tar

• Archives files
• Usage: tar [options] [archive_name] [files/directories]
• Usage: tar -cvf archive.tar files/ "compress files from 'files' directory into archive.tar"

Common options:

 -c: Create archive
 -x: Extract archive
 -v: Verbose
 -f: Specify archive file
 -t: List the contents inside the tar file
 -z: Gzip the file after tar'ing it. "Double compressed"

b) gzip

• Compresses files
• Usage: gzip [filename]

c) gunzip

• Decompresses gzip files
• Usage: gunzip [filename.gz]