ChmodTest Guides & Examples
Practical, no-fluff documentation for ChmodTest — written by people who hit the problems first.
About ChmodTest
What chmodtest computes from an octal or symbolic mode, how it handles special bits and invalid input, and the two companion tools for umask and symbolic changes.
ChmodTest Changelog
Dated changes to chmodtest.net — what the measured edge cases found, and which ones were documented rather than silently changed.
chmod Special Bits and Directories: setuid, setgid, sticky and x on a Directory
What the fourth octal digit means, how s and t appear in the symbolic form, what execute means on a directory, and the GNU chmod rules the symbolic calculator applies.
umask Explained: Why 022 Gives 644 and Directories 755
How a umask removes permission bits at creation time, why files never get execute from it, how to pick a umask for a target mode, and why chmod ignores it.
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