What is "umask" and how does it work?
- by Lekensteyn
I believe that umask is something that controls file permissions, but do not fully understand it.
After running umask 0644 in a terminal, I cannot read the files I create with the command-line text editor nano. I noticed that the permissions of that file are set to 0022 instead of the default 0755.
How does umask work? I thought I could just remove the each digit in the umask from 0777, 7 - 6 = 1 and 7 - 4 = 3, so I expect the permissions to be 0133, but apparently, this is not the case.
What is umask exactly? Explain it to me like I was a "Linux noob"
How do I calculate with umask?
What are use cases for umask?