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Quick Guide to Changing Permissions in Linux

This guide explains how to change file and folder permissions in Linux using the chmod command, including recursive operations. This guide also includes a permission cheat sheet.

Changing Permissions for Files and Folders

Basic Syntax for chmod:

chmod [permissions] filename

Replace [permissions] with the desired permission values and filename with the actual file or folder name.

Using chmod Recursively: To change permissions for a folder and all its subdirectories and files, use the -R option:

chmod -R [permissions] foldername

Running chmod as Root: If a file or folder is owned by root or another user, you may need sudo to change its permissions:

sudo chmod [permissions] filename

Numeric vs. Symbolic Permissions:

Numeric: Permissions are specified with a three-digit number.
Symbolic: Permissions are set with symbols like u, g, o, a, combined with +, -, or = to add, remove, or set permissions.

Cheat Sheet: Permission Codes

Permission	Numeric	Symbolic	Meaning
`r`	4	`r`	Read
`w`	2	`w`	Write
`x`	1	`x`	Execute
`-`	0	`-`	No permission

Common Permission Values

Numeric Code	Symbol	Permissions for `user`, `group`, `others`
`777`	`rwxrwxrwx`	Read, write, and execute for all
`755`	`rwxr-xr-x`	Full for user, read/execute for group and others
`644`	`rw-r--r--`	Read/write for user, read for group and others
`700`	`rwx------`	Full for user, none for group and others

Examples

Change File Permissions to 644:

chmod 644 myfile.txt

This gives the owner read and write permissions, while others have read-only access.

Change Folder Permissions Recursively to 755:

chmod -R 755 myfolder/

This sets full permissions for the owner, and read/execute for everyone else on all files and subfolders.

Set Permissions Symbolically:

chmod u+rwx,go+rx myfile.txt

This grants the user full permissions, and read/execute permissions to group and others.

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