Random unix permissions with open (using C)

son_t · 07-30-2007, 05:00 AM

Hello

I use the following C code (compiled with gcc on various platforms):

outFd=open(fname,O_RDWR | O_CREAT | O_TRUNC);

to create a file to write to, and I seem to get random Unix permissions:

Code:

----r-----   1 Son  Son          1G Jul 28 09:19 12061823-Lunar_Jim.ts
--w-------   1 Son  Son       1010M Jul 28 09:04 01061822-Lunar_Jim.ts
--w-r-----   1 Son  Son        973M Jul 28 08:23 31051822-Lunar_Jim.ts
--wx------   1 Son  Son       1000M Jul 28 08:11 30051822-Lunar_Jim.ts
--wxr-----   1 Son  Son        719M Jul 27 22:10 29051827-Lunar_Jim.ts
-rwxr-----   1 Son  Son          1G Jul 27 22:01 14061822-Lunar_Jim.ts

Anyone know why this is, and how I can make the permissions more consistent?

Thanks

jlliagre · 07-30-2007, 05:27 AM

Your code is missing a third argument to the open() call, which states precisely the file permissions.

son_t · 07-30-2007, 06:35 AM

Hko · 07-30-2007, 06:55 AM

Quote:

Originally Posted by son_t

Yes, correct.
I would do just this myself though:

Code:

outFd=open(fname, O_RDWR|O_CREAT|O_TRUNC, 0755);

(BTW what happened when you tried?)

son_t · 07-30-2007, 07:59 AM

Thanks, I didn't know you could just type the chmod octets there! It works a treat with the or-ing of the constants...