my $target = 'this is a test of the servise'; 
 
if ($target =~ /test/) { 
    $target =~ s//test2/; 
} 
 
if ($target =~ /nothing/) { 
    $target = s//null/; 
} else { 
    $target =~ s//foo/; 
}
[download]

My guess is that this returns this is a foo2 of the servise as documented in perlop:

               [....] If the pattern evaluates to the empty
               string, the last successfully executed regular
               expression is used instead. [....]
[download]

And so my standard admonition about "don't use $1 except in the context of a conditional" would also apply here, since "most recent success" is contextual.

-- Randal L. Schwartz, Perl hacker