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Re: [vox-tech] how does umask work?
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Re: [vox-tech] how does umask work?



Notice that you're not subtracting, but taking AND of the NOT of the
UMASK.  So there are two inputs involved:

   1. UMASK (i.e. - 022)
   2. Program creating the file/directory -- this program will request
      a desired file/directory mode (i.e. - 0777).

And the output is the AND of the requested mode and the NOT of the UMASK:

   mode = ~UMASK & requested
        = ~022 & 0777
        = 0755 & 0777
        = 0722

As Foo pointed out, most programs that create files (ie - touch) do not
request execution bits (they usually request 0666).  Programs that create
directories (ie - mkdir) generally do, however (they generally request
0777).

The desired mode is requested via "creat" and "open" system calls.  `man
creat` for more info.  BTW, the manpage also has a little blurb about
large file support flags, too.

-Mark

---
Mark K. Kim
http://www.cbreak.org/mark/
PGP key available upon request.


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