chmod calculator
Tick the permissions, or type an octal code or symbolic notation.
Read (r)
Write (w)
Execute (x)
Owner
Group
Others
Special bits
Command
chmod 644 file
The chmod command on Linux and macOS sets file permissions for three classes: owner (user), group and others. Each class can be allowed to read (r = 4), write (w = 2) and execute (x = 1). The sum gives one octal digit: 7 = rwx, 6 = rw-, 5 = r-x, 4 = r--.
Common values: 644 for files (owner reads and writes, everyone else reads), 755 for directories and scripts, 600 for private keys and configs with passwords. The special bits setuid, setgid and sticky add a fourth leading digit: 4755, 2775, 1777.