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About this tool
See the exact file and directory permissions any umask value produces, with symbolic form, a reverse calculator and safety warnings.
This calculator shows the exact permissions any umask value produces, using the POSIX rule that new files get 666 & ~umask and new directories get 777 & ~umask. It is built for Linux and Unix administrators tuning /etc/login.defs, shell profiles or systemd UMask= settings, and it also works backwards — enter the directory mode you want and get the umask that produces it.
Open Umask Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Shows both results at once, since the 666 and 777 bases give different outcomes for the same umask.
Enter the directory mode you want and get the umask that yields it, plus the file mode that follows.
Warns when a umask leaves files world-writable or strips permissions from the owner.
New files get 644 (rw-r--r--) and new directories get 755 (rwxr-xr-x). The mask clears the write bit for group and others: 666 & ~022 = 644 for files, 777 & ~022 = 755 for directories. 022 is the default on most Linux distributions.
Because programs request mode 666, not 777, when creating regular files — the execute bit is absent before the umask is even applied, and a umask can only remove bits, never add them. Directories are requested at 777, which is why they do end up executable (searchable).
022 removes group write, giving files 644 and directories 755; 002 keeps group write, giving 664 and 775. Distributions using user-private groups (Debian, Ubuntu, Fedora) often default to 002 because each user has their own primary group, making group write harmless for personal files.
Yes for confidentiality — 077 gives files 600 and directories 700, so only the owner has any access. It is common on hardened servers and for service accounts, but on shared project machines it breaks group collaboration, so teams usually pick 027 as a middle ground.
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