NEED HELP UNDERSTANDING UMASK.

From: Shel Sherman (ssherm32_at_sbcglobal.net)
Date: 07/22/05 

Date: Fri, 22 Jul 2005 13:39:39 GMT

I need help in understanding the following use of umask.

I ran several values of umask, created empty files using "touch" called
foo1, foo2, etc. and
 looked at the resulting permissions via ls -l for each value of umask. The
results are tabulated
below. Some results were as expected. Others leave me scratching my head.

UMASK RESULT OCTAL EQUIV. EXPECTED
0022 rwxr_xr_x 755 yes
0777 --------- 000
yes
 0321 r__r__rw_ 446 NO
0210 r__rw_rw_ 466 NO
0111 rw_rw_rw_ 666 yes
0123 rw_r__r__ 644 NO

Note that three of the six masks used did not yield the expected results.
For example, using a mask
of 0321 (octal) and then creating an empty file I expected to find the
permissions as
r _ _ r _ x r w _. Instead what I got was r _ _ r _ _ r w _ which
corresponds to 446 instead of the expected 456.

So I remain.....confused. Help would be appreciated.

Shel Sherman

Relevant Pages

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