Chmod Calculator
Toggle permission bits or type an octal mode to see the equivalent Unix permission string. Special bits are shown alongside the ordinary read, write, and execute settings.
Symbolic permissions
rw-r--r--
- Octal mode
- 644
- Regular file command
- chmod 644 example.txt
- Owner permissions
- rw-
- Group permissions
- r--
- Other permissions
- r--
Why 644 and 755 differ
Each ordinary digit adds read (4), write (2), and execute (1) permissions for one class of user. In 644, the owner gets 6, or read plus write. Group members and everyone else get read access only. With 755, the owner can also execute, and the remaining classes receive read plus execute.
Directory permissions have distinct effects: read lists names, execute permits searching or traversing the directory, and write permits directory-entry changes subject to other checks. A permission that is suitable for a script may not be suitable for a private configuration file.
Interpreting s, S, t, and T
The optional leading octal digit holds setuid (4), setgid (2), and sticky (1). In the symbolic display, lowercase s or t means the corresponding execute bit is also enabled. Uppercase S or T means the special bit is enabled without execute.
This widget describes mode bits; it does not inspect ownership or access-control lists on your machine. Its example command targets a regular file named example.txt. GNU chmod can preserve directory setuid or setgid bits in some numeric-mode operations, so consult its directory rules when applying a mode to a folder.