Here is the problem:

Parent redirects STDOUT and STDERR to something else and then fork.

The child process needs to exec an external problem, e.g., "tar -cf - something". But the external problem relies on the fact that stdout and stderr are with file descriptor 1 and 2.

Since stdin is not redirected yet, I can get the tty name and reopen STDOUT and STDERR in the child process to the tty before exec(). However this seems not working, because the new STDOUT and STDERR will have fds different from 1 and 2.

In essence, I need to have dup2(oldfd, newfd) functionality in Perl. I wonder if there is anyway to do this? I looked at the Perl source code and it seems not possible.

Fred Xia

In reply to dup2 exact file descriptor by fxia

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