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Monday, 18 May 2015

umask command in unix

umask command in unix

What is umask?
It is a number which define the default permissions which are not given on a file or directory.

Calculation of Umask:
You can simply subtract the umask from the base permissions to determine the final permission for file as follows.

Suppose umask 000
It means User has 0, Group has 0 and other has also 0
It means folder permission
User permission is      7-0 =7 (Read, Write and Execute)
Group Permission is   7-0 =7 (Read, Write and Execute)
Other Permission is    7-0 =7 (Read, Write and Execute)


Suppose umask 002
It means User has 0, Group has 0 and other has 2
It means folder permission
User permission is     7-0 =7 (Read, Write and Execute)
Group Permission is   7-0 =7 (Read, Write and Execute)
Other Permission is    7-2 =5 (Read and Execute)


Suppose umask 022

It means User has 0, Group has 2 and other has 2
It means folder permission
User permission is      7-0 =7 (Read, Write and Execute)
Group Permission is   7-2 =5 (Read and Execute)
Other Permission is    7-2 =5 (Read and Execute)


Suppose umask 027

It means User has 0, Group has 2 and other has 2
It means folder permission
User permission is      7-0 =7 (Read, Write and Execute)
Group Permission is   7-2 =5 (Read and Execute)
Other Permission is    7-7 =0 (No permission)


UmaskUser permissionGroup permissionOthers permission
000allallall
002allallread & execute
022allread / executeread / execute
027allread / executeNo permission

How to find out the umask value?

$ umask
0022

How to change the Umask?

$ umask 002


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