๐Chmod Calculator
chmod (change mode) is the Unix/Linux command for setting file and directory access permissions. Permissions are defined for three entities โ owner, group, and other โ each with read (r=4), write (w=2), and execute (x=1) bits. The sum of the set bits for each entity gives one octal digit; for example rwx=7, rw-=6, r--=4. This tool lets you set permissions visually with checkboxes, or enter an octal value directly to reverse-calculate the symbolic notation, then copy the resulting chmod command in one click.
How to Use
- 1Choose a preset or set checkboxes
Click a common preset (644, 755, etc.) or check individual read/write/execute boxes for owner, group, and other in the permission table.
- 2Enter an octal value directly (reverse lookup)
Type any octal number (0โ7777) into the octal input field and the checkboxes and symbolic notation will update automatically.
- 3Set special bits (optional)
Enable setuid, setgid, or sticky bit if needed. The execute column shows s/S or t/T depending on whether the execute bit is also set.
- 4Copy the command
Click the copy button in the terminal area at the bottom to copy the ready-to-use chmod command to your clipboard.
Tips
- ๐กWeb server config files are typically set to 644 (owner read/write, group/other read-only).
- ๐กExecutable scripts and directories are commonly set to 755 (owner full, group/other read+execute).
- ๐กSSH private key files (.pem) must be 600 (owner read/write only) or SSH will refuse to use them.
- ๐กsetuid (4xxx) runs the file as its owner, setgid (2xxx) runs it as its group, sticky (1xxx) prevents others from deleting files in a shared directory like /tmp.
- ๐กClick any row in the reference table to apply that permission immediately.