Linux file permissions

Chmod table

Example: bash chmod 600 file.txt

• With chmod you can set file permissions using a numerical value or a combination of symbols which represents the 3 permissions which can be assigned to the user, users group , or the “others” group.

Each of the permissions in the 3 digits you see above translate to the following

chmod Numerical Permission Settings

Numerical Value	Symbolic Representation	Permissions for Owner	Permissions for Group	Permissions for Others	Example Usage
0	—	None	None	None	chmod 000 file (no access)
1	–x	Execute	None	None	chmod 100 file
2	-w-	Write	None	None	chmod 200 file
3	-wx	Write & Execute	None	None	chmod 300 file
4	r–	Read	None	None	chmod 400 file
5	r-x	Read & Execute	None	None	chmod 500 file
6	rw-	Read & Write	None	None	chmod 600 file
7	rwx	Read, Write & Execute	None	None	chmod 700 file (full access for owner)

Common Full chmod Examples

Command	Numerical Value	Owner Permissions	Group Permissions	Other Permissions	Description
chmod 644 file	644	rw-	r–	r–	Owner can read/write, others can read.
chmod 755 file	755	rwx	r-x	r-x	Owner has full access, others can read/execute.
chmod 700 file	700	rwx	—	—	Owner has full access, others have no access.
chmod 600 file	600	rw-	—	—	Owner can read/write, others have no access.
chmod 777 file	777	rwx	rwx	rwx	Everyone has full access (read, write, execute).

Explanation of Permissions

• r: Read
• w: Write
• x: Execute

The numerical value is represented as a combination of three numbers (e.g., 755), each specifying the permissions for the owner, group, and others.

• The first digit is for owner.
• The second digit is for group.
• The third digit is for others.

Numerical Values:

• 0: No permissions
• 1: Execute (--x)
• 2: Write (-w-)
• 3: Write & Execute (-wx)
• 4: Read (r--)
• 5: Read & Execute (r-x)
• 6: Read & Write (rw-)
• 7: Read, Write & Execute (rwx)