What is umask in Linux?
Umask is a C-shell built-in command which allows you to determine or specify the default access (protection) mode for new files you create. (See the help page for chmod for more information on access modes and how to change modes for existing files.)
What does umask 22 mean?
Brief summary of umask value meanings: umask 022 – Assigns permissions so that only you have read/write access for files, and read/write/search for directories you own. All others have read access only to your files, and read/search access to your directories.
What does umask 777 mean?
As you have set the umask to remove the read/write bits for the owner and the read bits for others, a default such as 777 in applications would result in the file permissions being 133 . This would mean that you (and others) could execute the file, and others would be able to write to it.
Where is umask?
On most of the Linux distributions, the default system-wide value is set in pam_umask.so or in /etc/profile file. By adding the value in ~/. bashrc file in the user’s home directory, we can make a umask value specific for the user.
How is umask calculated?
For example, if umask is set to 022, 22 is displayed. To determine the umask value you want to set, subtract the value of the permissions you want from 666 (for a file) or 777 (for a directory)….Default File Permissions ( umask )
| umask Octal Value | File Permissions | Directory Permissions |
|---|---|---|
| 3 | r– | r– |
| 4 | -w- | -wx |
| 5 | -w- | -w- |
| 6 | –x | –x |
What is a umask value?
The umask value contains the permission bits that will NOT be set on the newly created files and directories. As we have already mentioned, the default creation permissions for files are 666 and for directories 777 . To calculate the permission bits of the new files, subtract the umask value from the default value.