echo -e "abc\ndef\nghi\n" | perl -wlne '! /def/ and print "$_";'

##</code><code>##

qwurx [shmem] ~> perl -MO=Deparse,-x -wlne '! /def/ and print "$_";'
BEGIN { $^W = 1; }                   # this is -w
BEGIN { $/ = "\n"; $\ = "\n"; }      # this is -l
LINE: while (defined($_ = <ARGV>)) { # and here is what -n does...
    chomp $_;                        # this belongs to -l
    print "$_" unless /def/;
}                                    # this belongs to -n too
-e syntax OK

##</code><code>##

perl -ne '}{ print $.'

##</code><code>##

perl -MO=Deparse,-x -ne '}{print$.'
LINE: while (defined($_ = <ARGV>)) {  # -n
    ();                               # script body - a noop
}                                     # script body
{                                     # script body
    print $.;                         # script body
}                                     # -n