Chmod Calculator.
Translate Unix file permissions between octal (755) and symbolic (rwxr-xr-x) notation. Tick the read / write / execute boxes for owner, group, and other — or type an octal value — and get a copy-ready chmod command, including the setuid, setgid, and sticky bits. Everything runs in your browser.
| Read 4 | Write 2 | Execute 1 | |
|---|---|---|---|
| Owner u | |||
| Group g | |||
| Other o |
How to read these.
Three digits, three audiences. An octal mode like 755 is one digit each for owner, group, and other. Each digit is the sum of read (4), write (2), and execute (1). So 7 = 4+2+1 (read, write, execute), 5 = 4+1 (read, execute), 6 = 4+2 (read, write). 755 is "owner can do everything; everyone else can read and run."
The symbolic form spells it out. rwxr-xr-x is the same thing in nine characters: rwx for owner, r-x for group, r-x for other, with a dash wherever a permission is absent. Directories reuse the bits with different meaning — x on a directory means "may enter / traverse," and r means "may list."
The fourth digit is special. A leading digit carries setuid (4), setgid (2), and the sticky bit (1). chmod 4755 sets setuid; the symbolic form shows it as an s in the execute slot (rwsr-xr-x). A capital S or T means the special bit is set without the matching execute bit — usually a mistake worth noticing.