Interesting question. Took me a lot longer than I expected. Did you know you can have perl statements inside your regex? 

#!/usr/bin/perl

for (@ARGV) {
    my $d;
    s!  (\d{2})/
        (\d{2})/
        (\d{2})
        (?{ $d = ($3 gt 55)?'19'.$3:'20'.$3;})
    !$d/$1/$2!ox;

    print; print "\n";
}

[download]
%./foo 01/02/03 02/14/08 01/02/89             
2003/01/02
2008/02/14
1989/01/02

[download]

s//----->\t/;$~="JAPH";s//\r<$~~/;{s|~$~-|-~$~|||s |-$~~|$~~-|||s,<$~~,<~$~,,s,~$~>,$~~>,, $|=1,select$,,$,,$,,1e-1;print;redo}

In reply to Re: Combining s/// by starbolin
in thread Combining s/// by kangaroobin

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