Linux Permission Calculator - Advanced chmod & Permission Analyzer

Special Permissions

SetUID (SUID)

When set, the file executes with the privileges of the file owner, regardless of who runs it.

Set User ID on execution 4000

SetGID (SGID)

For files: execute with group privileges. For directories: new files inherit directory's group.

Set Group ID on execution 2000

Sticky Bit

When set on a directory, only the file owner can delete or rename files within that directory.

Restricted deletion flag 1000

Quick Permission Presets

Web Server Files Common

0755

rwxr-xr-x

Owner: full, Group/Others: read & execute

Configuration Files

0644

rw-r--r--

Owner: read/write, Group/Others: read only

Private Scripts

0700

rwx------

Owner only: full access

Public Directory Warning

0777

rwxrwxrwx

Everyone: full access (insecure)

SUID Executable

4755

rwsr-xr-x

SetUID + normal executable

Sticky Temp Directory

1777

rwxrwxrwt

World-writable with sticky bit

Private Files

0600

rw-------

Owner only: read/write

SGID Directory

2755

rwxr-sr-x

SetGID + normal directory

Permission Reference Guide

Numeric Values

Symbolic Notation

Common Examples

Special Bits

Octal Value	Binary	Permissions	Description
0 000	000	---	No permissions
1 001	001	--x	Execute only
2 010	010	-w-	Write only
3 011	011	-wx	Write & Execute
4 100	100	r--	Read only
5 101	101	r-x	Read & Execute
6 110	110	rw-	Read & Write
7 111	111	rwx	Read, Write & Execute

Symbol	Meaning	Octal	Description
r	Read	4	Read file or list directory
w	Write	2	Modify file or directory contents
x	Execute	1	Execute file or enter directory
s	SetUID/SetGID	4/2	Special execute with owner/group privileges
t	Sticky	1	Restricted deletion in directories
-	None	0	Permission not granted

Use Case	Octal	Symbolic	chmod Command
Secure configuration file	600	rw-------	chmod 600 config.conf
Public web directory	755	rwxr-xr-x	chmod 755 public_html/
Shared group directory	775	rwxrwxr-x	chmod 775 shared/
Read-only documentation	444	r--r--r--	chmod 444 README.md
SUID root binary	4755	rwsr-xr-x	chmod 4755 /usr/bin/passwd
Sticky temp directory	1777	rwxrwxrwt	chmod 1777 /tmp

Special Bit	Octal	Symbol	Effect
SetUID (SUID)	4000	s in user execute	File runs with owner's privileges
SetGID (SGID)	2000	s in group execute	File runs with group's privileges
Sticky Bit	1000	t in others execute	Only owner can delete files in directory
SetUID + SetGID	6000	s in both	Both special bits set (rare)
All Special Bits	7000	all special	SUID + SGID + Sticky (rare)

Advanced Linux Permission Calculator

Numeric (Octal) Input