Basic-Commands.md

Basic Linux Commands

pwd

Prints the current working directory.

Example:

pwd

ls

Lists files and directories in the current directory.
Syntax:

ls [options] [directory]

Examples:

• Current location available file/directory list

  ls
  

• Detailed view

  ls -l
  

• Show hidden files

  ls -a
  

• Human-readable sizes

  ls -lh
  

• Recursive listing

  ls -R
  

cd

Changes the current directory.
Syntax:

cd [directory]

Examples:

• Go to a specific folder

  cd /home/user/documents
  

• Move up one level

  cd ..
  

• Go to root

  cd /
  

mkdir

Creates a new directory.
Syntax:

mkdir [directory_name]

Examples:

• Create a single directory

  mkdir new_folder
  

• Create nested directories

  mkdir -p parent/child/grandchild
  

rmdir

Deletes an empty directory.
Syntax:

rmdir [directory_name]

Example:

rmdir old_folder

rm

Removes files or directories.
Syntax:

rm [options] [file/directory]

Examples:

• Remove a file

  rm file.txt
  

• Remove a folder and its contents

  rm -rf foldername
  

File Operations

touch

Creates an empty file.
Syntax:

touch [filename]

Example:

touch myfile.txt

cat

Displays the contents of a file.
Syntax:

cat [filename]

Example:

cat file.txt

cp

Copies files and directories.
Syntax:

cp [options] source destination

Examples:

• Copy a file

  cp file.txt /backup/
  

• Copy a directory

  cp -r myfolder newfolder
  

mv

Moves or renames files and directories.
Syntax:

mv [source] [destination]

Examples:

• Rename a file

  mv oldname.txt newname.txt
  

• Move a file

  mv file.txt /new/location/
  

ln

Creates links between files.
Syntax:

ln [options] target link_name

Examples:

• Symbolic link

  ln -s /path/to/file symlink
  

• Hard link

  ln /path/to/file hardlink
  

System Information

date

Displays the current date and time.
Syntax:

date

Example:

date

uptime

Shows how long the system has been running.
Syntax:

uptime

Example:

uptime

uname -a

Displays system and kernel information.
Example:

uname -a

User and Session Information

whoami

Displays the currently logged-in user.
Example:

whoami

who

Lists all logged-in users.
Example:

who

id

Displays user ID and group information.
Syntax:

id [username]

Example:

id user

Process and Memory Information

ps -aux

Lists all running processes.
Example:

ps -aux

top

Shows real-time system statistics.
Syntax:

top

Example:

top

free -h

Displays memory and swap usage in a human-readable format.
Example:

free -h

System Shutdown and Reboot

shutdown

Shuts down or reboots the system.
Syntax:

shutdown [options] [time]

Examples:

• Power off immediately

  shutdown -P now
  

• Restart immediately

  shutdown -r now
  

• Cancel scheduled shutdown

  shutdown -c
  

reboot

Reboots the system.
Example:

reboot