About Linux Permissions and Umask Calculator

Converts Linux permission modes in both directions and makes every bit directly editable. It handles owner, group, and other read/write/execute permissions plus setuid, setgid, and sticky bits, including the uppercase symbolic forms used when the matching execute bit is absent. The umask calculator applies the actual 0666 file and 0777 directory creation bases.

• Accepts three-digit or four-digit octal notation and nine-character symbolic notation.
• Explains how special bits differ between regular files and directories.
• Calculates umask results with bit removal, not decimal subtraction.
• Does not read a filesystem path or retain any permission value.

Frequently Asked Questions

Why does umask 022 produce 0644 for files but 0755 for directories?

New regular files start without execute bits at 0666, while directories start at 0777. The same umask removes group and other write permission from each base.

What do uppercase S and T mean?

The special bit is set while the matching execute bit is not. Lowercase s or t means both the special bit and execute bit are set.