$ mkdir lloderl74
$ cat > lloderl74/script1
#!/usr/bin/perl -w
print "Hello World!\n";
exit;
$ cat > lloderl74/script2
#!/usr/bin/perl -w
die "Goodbye, Cruel World\n";
$ perl -pi.bak -e '
s{^(#!/usr/bin/perl.*)}{$1\n\nuse English q{no_match_vars}}' lloderl74/*
$ head -99 lloderl74/*
==> lloderl74/script1 <==
#!/usr/bin/perl -w

use English q{no_match_vars}
print "Hello World!\n";
exit;

==> lloderl74/script1.bak <==
#!/usr/bin/perl -w
print "Hello World!\n";
exit;

==> lloderl74/script2 <==
#!/usr/bin/perl -w

use English q{no_match_vars}
die "Goodbye, Cruel World\n";

==> lloderl74/script2.bak <==
#!/usr/bin/perl -w
die "Goodbye, Cruel World\n";