Re-open the STDIN file handle How to rewind the STDIN file handle?

See also Dealing with Files

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In special cases it can be needed to re-read from the STDIN file handle, e.g. in a mail or Listserver processing with Perl. There might be even more sophisticated solutions on this problem but the following one will work. If you had a better recipe please let me know.

How to test this example:

ls -l /tmp | script.pl

Recipe

#!/usr/bin/perl -w
use strict;
$| = 1;

local *FH;

*FH = &stdin(); # Now you have a rewind-able file handle to your STDIN data

# -- first run
while(<FH>) {
        print "[R1]=> $_";
}

seek(FH, 0, 0);

# -- second run
while(<FH>) {
        print "[R2]=> $_";
}

sub stdin () {
        my $tempfile = time() . '_' . int(rand(1000000));
        open(TEMP, "+>/tmp/temp_$tempfile") or print STDERR $!;
        local $/ = undef;
        print TEMP <STDIN>;
        seek(TEMP, 0, 0);
        \*TEMP;
}