cat lorem.txt

Lorem ipsum dolor sit amet, consectetur adipisci elit,
sed do eiusmod tempor incidunt ut labore et dolore magna aliqua.
Lorem ipsum dolor sit amet, consectetur adipisci elit,
sed do eiusmod tempor incidunt ut labore et dolore magna aliqua.


perl -M"5;$S=shift;$R=shift;open $o,'>','new2.txt'" -ne "chomp;if($_=~/$S/){print qq/$_ $R?/;($_=$_)=~s/$S/$R/ if<STDIN>=~/y/}print$o $_.$/"  ipsum REPLACE lorem.txt

Lorem ipsum dolor sit amet, consectetur adipisci elit,  REPLACE?   y
Lorem ipsum dolor sit amet, consectetur adipisci elit,  REPLACE?   n

cat new2.txt

Lorem REPLACE dolor sit amet, consectetur adipisci elit,
sed do eiusmod tempor incidunt ut labore et dolore magna aliqua.
Lorem ipsum dolor sit amet, consectetur adipisci elit,
sed do eiusmod tempor incidunt ut labore et dolore magna aliqua.


##</code><code>##

perl -MO=Deparse -M"5;$S=shift;$R=shift;open $o,'>','new2.txt'" -ne "chomp;if($_=~/$S/){print qq/$_ $R?/;($_=$_)=~s/$S/$R/ if<STDIN>=~/y/}print$o $_.$/"
sub BEGIN {
    require 5;
    ()
}
$S = shift @ARGV;
$R = shift @ARGV;
open $o, '>', 'new2.txt';
LINE: while (defined($_ = readline ARGV)) {
    chomp $_;
    if ($_ =~ /$S/) {
        print "$_ $R?";
        ($_ = $_) =~ s/$S/$R/ if readline(STDIN) =~ /y/;
    }
    print $o $_ . $/;
}
-e syntax OK