Linux Basics¶

Essential Commands¶

Command	Purpose
`ls`	Lists the contents of the current directory
`ls -sS`	Lists files sorted by size and shows their sizes
`ls -l`	Displays detailed information about files
`ls -a`	Shows hidden files (files starting with a dot)
`ls -lh`	Lists files with human-readable sizes

Command	Purpose
`cd <name>`	Navigate to a specified directory
`cd ..`	Move up one directory level
`cd -`	Switch to the previous directory
`cd ~`	Return to the home directory
`cd /path/to/directory`	Jump directly to an absolute path

Command	Purpose
`pwd`	Displays the current directory path

Command	Purpose
`echo <text>`	Prints the specified text
`echo $PWD`	Displays the current directory environment variable
`echo $USER`	Displays the current user's username
`echo "Hello" > file.txt`	Writes text to a file

Command	Purpose
`mkdir <directory_name>`	Creates a new directory
`mkdir -p <path/to/dir>`	Creates nested directories as needed
`mkdir -p projects/{project1,project2}`	Creates structured directories

Command	Purpose
`touch <file_name>`	Creates an empty file
`touch existing_file.txt`	Updates the timestamp of an existing file
`touch file1.txt file2.txt`	Creates multiple files at once

Command	Purpose
`rm <file_name>`	Deletes a specified file
`rm -i`	Prompts for confirmation before deletion
`rm -rf <directory_name>`	Forcefully deletes a directory and its contents
`rm *.log`	Deletes all `.log` files in the directory
`find . -name "*.tmp" -exec rm {} +`	Deletes files by criteria

Command	Purpose
`cat <file_name>`	Displays the contents of a file
`cat <file_name> -n`	Displays file contents with line numbers
`cat file1 file2 > combined.txt`	Combines multiple files into one
`cat /var/log/syslog \| grep error`	Example of searching for logs

Command	Purpose
`cp <source> <destination>`	Copies a file to a new location
`cp -r src_dir dest_dir`	Copies directories recursively
`cp -u <file> backup/`	Copies only newer files

Command	Purpose
`mv <source> <destination>`	Moves or renames a file
`mv <file1> <file2> <destination_directory>`	Moves multiple files
`mv old_dir new_dir`	Renames a directory
`mv *.txt documents/`	Organizes files by type

Command	Purpose
`which <command>`	Shows where a command is located

Command	Purpose
`chmod <options> <file>`	Modifies file permissions

Command	Purpose
`chown <owner>:<group> <file>`	Changes the owner and group of a file

Command	Purpose
`sudo <command>`	Runs a command with administrative privileges

Command	Purpose
`grep <pattern> <file>`	Searches for a pattern in a file

Command	Purpose
`sed 's/pattern/replace/' <file>`	Replace text in a file

Command	Purpose
`realpath <file>`	Displays the absolute path of a file