How do I check the current umask value?

Simply type 'umask' in your terminal to display the current umask value in octal notation. For example: umask will output something like 0022.

How do I set a new umask value?

Use 'umask XXX' where XXX is the octal value you want to set. For example: umask 002 will set the umask to 002. This change is usually temporary for the current session unless set in a shell configuration file.

umask Command

Q: What does the umask command do in Linux?

The umask (user file-creation mode mask) command is used to set the default file permissions for newly created files and directories. It specifies which permission bits are to be cleared (masked) when a new file or directory is created.

The umask (user file-creation mode mask) command in Linux is used to set the default file permissions for newly created files and directories. It specifies which permission bits are to be cleared (masked) from the maximum possible permissions (666 for files, 777 for directories) when a new file or directory is created.

Syntax

umask [-p] [-S] [mode]

Description

The umask command is a shell built-in that affects the permissions of files and directories created by the current user. The umask value is a three-digit octal number that represents the permissions that are *removed* from the default permissions. For files, the default is 666 (rw-rw-rw-), and for directories, it's 777 (rwxrwxrwx).

Common uses include:

Setting default permissions for new files and directories
Enhancing security by restricting default access
Ensuring consistent permissions across a user's session
Understanding how file permissions are derived

Common Options

Option	Description
`-p`	If the mode argument is omitted, the current umask is printed in a form that can be reused as input.
`-S`	If the mode argument is omitted, the current umask is printed in symbolic form.

Examples

Check current umask

umask

Displays the current umask value in octal notation (e.g., 0022).

Check current umask in symbolic mode

umask -S

Displays the current umask value in symbolic mode (e.g., u=rwx,g=rx,o=rx).

Set umask to 002

umask 002

Sets the umask to 002. New files will have 664 (rw-rw-r--) and new directories 775 (rwxrwxr-x) permissions.

Set umask to 077

umask 077

Sets the umask to 077. New files will have 600 (rw-------) and new directories 700 (rwx------) permissions, restricting access to the owner only.

Create a file and observe permissions

                        umask 022

                        touch newfile.txt

                        ls -l newfile.txt

Sets umask to 022, creates a file, and then lists its permissions to demonstrate the effect.