Chmod Calculator

How permissions are numbered

Each of the three groups (owner, group, others) gets a digit that is the sum of read (4), write (2) and execute (1). So 7 is read+write+execute, 5 is read+execute and 4 is read only. A mode of 755 means the owner can do everything and everyone else can read and run.

Common modes

• 644 (rw-r--r--): regular files such as web pages.
• 755 (rwxr-xr-x): executables and directories.
• 600 (rw-------): private files such as SSH keys.
• 700 (rwx------): private directories such as ~/.ssh.

Special bits

setuid and setgid run an executable as its owner or group. The sticky bit on a directory such as /tmp stops users from deleting each other's files. A capital S or T in the symbolic form means the special bit is set but the execute bit is not.