chmod / Permission Calculator
Convert Unix file permissions between octal, symbolic and plain English.
What you provide
Result
755 = rwxr-xr-x
Owner, group and others each get read, write and execute independently. On a directory, execute means the right to enter it.
Mode 755
Owner 7 · Group 5 · Others 5 — a set bit is granted, a dash is denied
- Owner
- Group
- Others
- Octal
- 755
- Symbolic
- rwxr-xr-x
- Owner
- read, write, execute
- Group
- read, execute
- Others
- read, execute
What this cannot tell you
- Pure arithmetic on the permission bits. It does not read or change any real file.
- Special bits (setuid, setgid, sticky) are the 4-digit octal form; a 3-digit chmod clears them.
Take this with you
How this calculation works
Enter a mode in either octal or symbolic form and the tool shows all representations and spells out what each of owner, group and others can do. Read is 4, write 2, execute 1, added together per group; a leading fourth octal digit carries the special bits.
What the results mean
- Owner / group / others
- Three independent sets of read, write and execute. On a directory, execute is the right to enter it.
- Special bits
- The fourth octal digit: setuid (4), setgid (2), sticky (1). A 3-digit chmod like 755 sets them to zero — use 0755 or 1777 to be explicit.
Frequently asked questions
What does 755 mean?
Owner can read, write and execute (7 = 4+2+1); group and others can read and execute but not write (5 = 4+1). It is the standard mode for a script or a directory you want everyone to use but only yourself to change.
Why did my setuid bit disappear?
Because you used a 3-digit chmod. The special bits live in a fourth leading digit, and a 3-digit mode clears them. Use the 4-digit form — 4755 for setuid, 1777 for the sticky bit — to keep them.
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