umask: What it means and how to calculateLots of people are confused by umask and why we have to subtract the desired permissions (755, for example) from 777 to get the desired result (022, in this case).
Think of is as unwanted mask as it removes the permissions you don't want. Using the example above, if we don't want group and world write access (rwxr-xr-x), we take out the ---w--w- giving us 022. If we want to take away all group and world permissions (---rwxrwx) then our umask is 077.
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