On 8 Mar, Devin Teske wrote: > Problem we had found was: > > Executing dd with a closed stdout and stderr would cause the summary > messages printed at the end to go into the destination output file. > > For example, > > dd if=/dev/zero of=/tmp/foo bs=1m count=1 > > Works fine, but the following: > > dd if=/dev/zero of=/tmp/foo bs=1m count=1 >&- 2>&- > > Will cause the summary statistics of dd to appear in /tmp/foo instead > of on the console. > > The issue is that the summary statistics are send to fd1, which if you > close down stdout and stdin, fd1 is actually the output file since it > got the lowest file descriptor available when open(2) was called on > the output file. > > This was never fixed because it was deemed ´silly developer, don˙t > close stdout and stderr before invoking ddˇ. > > The argument has been made by Jilles T. that it is generally a bad > idea to close down any of the standard file descriptors because it > cannot be predicted how a particular UNIX utility will react (e.g., in > the case of dd, causing a simple printf(3) to go to an unexpected > location). Shades of: - From our Harris VOS system. JOBCNTRL ER 2211 : IT'S NOT NICE TO FOOL POP! >he 2211 YOU JUST TRIED TO FAKE-OUT MOTHER NATURE, AND SHE CAUGHT YOU! SUPER- VULCAN NOW HAS YOUR NAME ON HIS ENEMY LIST, AND YOU CAN BE CERTAIN THAT FUTURE ATTEMPTS TO RESOURCE LFN 0,3,OR 6 WILL RESULT IN YOUR BEING ABORTED, SPINDLED, MANGLED, FOLDED, PUNCHED, DELETED, AND DEALLOCATED.Received on Wed Mar 08 2017 - 23:20:00 UTC
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