Opens a pair of connected pipes like the corresponding system call.
Note that if you set up a loop of piped processes, deadlock can occur
unless you are very careful. In addition, note that Perl's pipes use
IO buffering, so you may need to set
to flush your WRITEHANDLE
after each command, depending on the application.
On systems that support a close-on-exec flag on files, the flag will be set for the newly opened file descriptors as determined by the value of $^F. See "$^F" in perlvar.