Default read/write/execute permissions - UNIX for Dummies Questions & Answers

joeyg · #1 08-25-2008

I am perplexed that my script execution is not always consistent in creating new files. Specifically, my group read/write/execute permissions. For instance, take a look at the following:

Code:

-rw-rw----   1 jg   dp  18648 Aug 22 10:06 nx081508.txt
-rw-rw----   1 jg   dp  22422 Aug 22 10:06 nx081808.txt
-rw-rw----   1 jg   dp   6993 Aug 22 10:06 nx081908.txt
-rw-rw----   1 jg   dp  25308 Aug 22 10:06 nx082008.txt
-rw-rw----   1 jg   dp  15873 Aug 22 10:06 nx082108.txt
-rw-rw----   1 jg   dp  95319 Aug 22 10:06 nx082208.all
-rw-r-----   1 jg   dp  88911 Aug 22 10:06 nx082208.txt
-rw-rw----   1 jg   dp  94518 Aug 22 10:06 nx082208.uid

One of my .txt files does not have group 'w' access. And this can become a problem is another user needs to do something with that file.

I know, I could have my script do a chmod to the *.txt files after it is done, but that seems silly.

So, any idea where this might be set such that users sometimes set correctly and sometimes not?

jim mcnamara · #2 08-25-2008

When you created the file, some app (example: an editor on another PC or on your unix box), writes the file for the first time and the umask value is different from your default umask. The protections persist unless you overwrite them.

apps may call umask, so that while running and creating files in your name, the protections are different.

man 2 umask

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