ЭЛЕКТРОННАЯ БИБЛИОТЕКА КОАПП |
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7.20. Copying FilehandlesProblemYou want to make a copy of a filehandle. SolutionTo create an alias for a filehandle, say: *ALIAS = *ORIGINAL; Use open(OUTCOPY, ">&STDOUT") or die "Couldn't dup STDOUT: $!"; open(INCOPY, "<&STDIN" ) or die "Couldn't dup STDIN : $!"; Use open(OUTALIAS, ">&=STDOUT") or die "Couldn't alias STDOUT: $!"; open(INALIAS, "<&=STDIN") or die "Couldn't alias STDIN : $!"; open(BYNUMBER, ">&=5") or die "Couldn't alias file descriptor 5: $!"; DiscussionIf you create an alias for a filehandle with typeglobs, only one Perl I/O object is still being accessed. If you close one of these aliased filehandles, the I/O object is closed. Any subsequent attempt to use a copy of that filehandle will give you an error like If you create a copy of a file descriptor with # take copies of the file descriptors open(OLDOUT, ">&STDOUT"); open(OLDERR, ">&STDERR"); # redirect stdout and stderr open(STDOUT, "> /tmp/program.out") or die "Can't redirect stdout: $!"; open(STDERR, ">&STDOUT") or die "Can't dup stdout: $!"; # run the program system($joe_random_program); # close the redirected filehandles close(STDOUT) or die "Can't close STDOUT: $!"; close(STDERR) or die "Can't close STDERR: $!"; # restore stdout and stderr open(STDERR, ">&OLDERR") or die "Can't restore stderr: $!"; open(STDOUT, ">&OLDOUT") or die "Can't restore stdout: $!"; # avoid leaks by closing the independent copies close(OLDOUT) or die "Can't close OLDOUT: $!"; close(OLDERR) or die "Can't close OLDERR: $!"; If you create an alias of a file descriptor using See AlsoThe |