in reply to O_RDWR, POSIX, OS, fs...
in thread open vs. sysopen

Perhaps you can supply some additional code, or a small test case that exhibits the behavior. The following two lines of code behave properly on my Slackware Linux box (2.4.18), assuming proper permissions on directories involved in the filepath.

open(DEST,'>',$ggg) or die $!; sysopen(DEST, $ggg, O_WRONLY | O_TRUNC | O_CREAT) or die $!;