Convert three-digit Unix permissions between octal, symbolic, and decimal forms.
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About Chmod Calculator
Work out Unix file permissions by toggling read, write and execute for owner, group and others, or by typing an octal mode; both stay in sync. Setuid, setgid and sticky bits are supported. The result is shown in octal, symbolic (rwxr-xr-x), ls -l style, symbolic assignment (u=rwx,g=rx,o=rx), binary and decimal, with ready-to-copy chmod commands, an optional -R flag and common presets such as 755, 644 and 600.
Common uses
- Find the right mode for a script, web root or SSH key
- Translate rwxr-xr-x from ls -l into an octal number
- Build a chmod command with setgid or the sticky bit
- Spot world-writable permissions before deploying
FAQ
- What does chmod 755 mean?
- 755 is rwxr-xr-x: the owner can read, write and execute, while the group and others can read and execute. It is common for directories and executable scripts.
- What does chmod 644 mean?
- 644 is rw-r--r--: the owner can read and write, and everyone else can only read. It is the usual mode for regular files.
- How are octal permissions calculated?
- Each digit is the sum of read (4), write (2) and execute (1) for owner, group and others in that order. An optional leading digit adds setuid (4), setgid (2) and sticky (1).
- What permissions should an SSH private key have?
- 600 (rw-------), so only the owner can read and write it. OpenSSH refuses to use a private key that other users can read.