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Umask
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Q: Why are file and directory permissions different for the same umask?

The umask is subtracted from a base of 666 for files and 777 for directories. Files never get the execute bit by default, which is why a file maxes out at 666.

Q: How do I set a umask permanently?

Add a line like umask 027 to your shell profile (~/.bashrc or ~/.profile), or to /etc/profile for all users.

Q: What umask is most secure?

077 gives new files 600 and directories 700 — only the owner has any access. Use it for private servers and sensitive data.

A umask masks bits off the default permissions. Enter a umask and instantly see the resulting permissions for new files and directories.

File perms

Dir perms

Symbolic

# umask 022 (typical)
file 666 - 022 = 644
dir 777 - 022 = 755

# umask 077 (private)
file 600 dir 700

Umask Value

New Files (base 666)

644

-rw-r--r--

New Dirs (base 777)

755

drwxr-xr-x

Common Umask Values

Frequently Asked Questions

What does umask 022 do?

It removes write permission for group and others. New files become 644 (rw-r--r--) and new directories become 755 (rwxr-xr-x). This is the default on most Linux systems.

Why are file and directory permissions different for the same umask?

The umask is subtracted from a base of 666 for files and 777 for directories. Files never get the execute bit by default, which is why a file maxes out at 666.

How do I set a umask permanently?

Add a line like umask 027 to your shell profile (~/.bashrc or ~/.profile), or to /etc/profile for all users.

What umask is most secure?

077 gives new files 600 and directories 700 — only the owner has any access. Use it for private servers and sensitive data.