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In this video you'll learn about umask and
how it is used to set default permissions.

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So the umask is a shell setting that defines
a mask that will be subtracted from the default permissions.

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It's normally set from the shell
startup files, etc profile and etc bashrc.

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And to understand it, default permissions on directories
are 777 and default permissions on false are 666.

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Now if you use the umask
of 022, which is pretty common, it

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will set default permissions on false
to 644 and on directories to 755.

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And if you have the umask of 027, it will set default
permissions on directories to 750 and on valves to 6, 4, 0.

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Let
me demonstrate.

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I'm typing umask and now we can
see that umask in fact it's four digits.

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The first digit is for the
special permissions. You do not ever want

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to modify your special permissions through
a umask. It really doesn't make sense.

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So ignore it. Pretend
as if it's not here.

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Now the result is that when
I use touch file 1 LS

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L on file 1 has
a permission mode set to 644.

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Now when I change my
umask to 0 to 7, I

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verify using the umask, it's
set to 0 to 7.

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And I use touch file 2 and LS L on
file 2 is showing that others has no permissions anymore.

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If you want your umask to be effective, you need
to set it through one of these shell startup files.

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But be careful, because if
you set 0 to 7, for

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instance, that means that others
in no case will have read

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permissions to files anymore. And
that might seriously mess up stuff.

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If I may give you an advice, leave your umask alone.
Your distribution is setting the umask the right way in most

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cases. So leave it alone. Don't mess with it, because
you might be in for some nice troubleshooting if you do.