Default permissions for umask- to create files or directories

The default permissions of files under linux are determined by the umask value.

Umask defines the default permissions for users to create files or directories through octal values.

Umask corresponds to a value that indicates prohibited permissions. The specific details, files and directories are slightly different.

The default umask for root is 0022

The default umask for the average user is 0002

Files: setting default permissions for users to create files

When umask is even, the default permission to create a file is: file maximum permission minus umask permission

For example, if umask is set to 044, the default permission of the file is 666-044room622, i.e.-rw--w--w-

When umask is odd, the default permission for creating a file is: the maximum permission of the file minus the umask permission, and the resulting odd digit plus 1

Example 1: if umask is set to 045, the default permission of the file is 666-045mm 621, odd digits plus 1, that is, 622, that is,-rw--w--w-

Example 2: if umask is set to 035, the default permission of the file is 666-035mm 631, odd digits plus 1, that is, 642, that is,-rw-r---w-

Directories: setting default permissions for users to create directories

Whether umask is even or odd, using 777-umask directly is the permission of the default directory.