umask — Default File Creation Permissions

umask controls the default permissions used when new files and directories are created. It does not change existing files; it only affects new ones created by the current shell or process.

Check the current umask

umask

A common output is:

0022

This usually means new files are created without write permission for group and others.

Temporarily change umask

umask 0027

This makes newly created files and directories more restrictive for users outside the owner and group.

Simple way to remember it

The umask removes permissions from the default. A stricter umask usually means fewer permissions on new files.