I am having a really hard time understanding how umask works.

How is something that is 666 masked with 001 still 666 ?

  • Why do you think it is? What commands did you run and what happened?
    – Mikel
    Jan 27, 2016 at 1:57

1 Answer 1


A umask value of 001 says that it is preventing the creation of files with other executable permissions. (Actually not preventing the creation, as preventing the executable-permissions).

A 666 mode in an open statement only permits user+group+other for read and write permissions. So the umask has no effect on that.

However umask does not affect chmod.


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