Umask: Difference between revisions
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The mask itself is applied as a bitwise AND operation then a bitwise NOT of that with the default 777 permisions eg., | The mask itself is applied as a bitwise AND operation then a bitwise NOT of that with the default 777 permisions eg., | ||
777 | |||
AND NOT 022 | AND NOT 022 | ||
= 755 | |||
The three popular [[umask]]s are 022, 002 and 000. | The three popular [[umask]]s are 022, 002 and 000. | ||
Revision as of 17:36, 16 June 2008
umask is the way the UNIX operating system determines what default permissions that files and directories are created with.
The mask itself is applied as a bitwise AND operation then a bitwise NOT of that with the default 777 permisions eg.,
777
AND NOT 022
= 755
The three popular umasks are 022, 002 and 000.
022
This as the example shows above that you will get full rwx for the user, r-x for the group and r-x for other. This is the default in almost all of our operating systems.
002
This would give full rwx for the user, full rwx for the group and give only r-x for other. This is helpful when you want your default group (or a SetGID directory) to have full control over the files and directories you create while allowing everyone else read and execute permissions.
000
This is the most restrictive umask and gives no permissions