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 dd”.
> 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
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