Symbolic Permission Calculator
Convert symbolic permission strings like rwxr-xr-- into octal chmod values.
Inputs
9-character string like rwxr-xr--, or with special bits like rwsr-xr-x
Octal Permission
754
chmod Command
chmod 754
Owner
7
Group
5
Others
4
Special Bits
0
Step by step
Owner triplet
rwx → 7
= 7
Group triplet
r-x → 5
= 5
Others triplet
r-- → 4
= 4
Special bits
None
= 0
Octal result
754
= 754
How it works
Symbolic permissions (the rwxrwxrwx string from ls -l) map directly to octal: each triplet (owner, group, others) converts by summing r=4, w=2, x=1. Special bits (SUID=4, SGID=2, sticky=1) form an optional leading digit. This calculator converts the human-readable ls -l output to the numeric form needed for chmod commands.
Formula
Triplet to octal
octal_digit = (r?4:0) + (w?2:0) + (x?1:0)
- r
- read bit present
- w
- write bit present
- x
- execute bit present
Frequently Asked Questions
What does 's' mean in a permission string?
Lowercase 's' in the owner's execute position means SUID is set AND execute is set. In the group position it means SGID+execute. Uppercase 'S' means the special bit is set but execute is NOT — which is usually a mistake.
What does 't' mean in the others position?
The sticky bit ('t' when execute is also set, 'T' without execute) on a directory means only the file owner, directory owner, or root can delete files within it — the classic example being /tmp with permissions 1777.