Chmod Calculator
Calculate Unix file permissions interactively. Toggle checkboxes or enter an octal value.
Octal Input
Permission Matrix
Owner
Group
Others
Read
Write
Execute
Special Permissions
Setuid
Setgid
Sticky
Enable
Common Presets
777rwx all
755owner rwx, others rx
644owner rw, others r
600owner rw only
444read-only all
700owner only
666rw all
4755setuid
2755setgid
1777sticky (/tmp)
Results
Octal
0755
Symbolic
rwxr-xr-x
chmod Command
chmod 0755 filename
ls -l Style
-rwxr-xr-x
About chmod and Unix file permissions
Every file on a Unix/Linux system has three permission groups: Owner (user who owns the file), Group (users in the file's group), and Others (everyone else). Each group can have Read (4), Write (2), and Execute (1) permissions.
The octal notation sums these values per group. For example, 755 means owner has 7 (4+2+1 = rwx), group has 5 (4+1 = r-x), and others have 5 (r-x).
Special permissions: Setuid (4) runs a file as its owner, Setgid (2) runs it as its group or inherits directory group, and the Sticky bit (1) restricts deletion in shared directories like /tmp. These form a fourth leading octal digit.