$ perl -le 'BEGIN { print "in begin" } eval { $i = <> ; $r = sqrt( -1 ) }; print ($@ ? "error: $@" : $r)'                                           
in begin
Can't take sqrt of -1 at -e line 1.

##</code><code>##

echo -1 | perl -le 'BEGIN { print "in begin" } eval { $i = <> ; $r = sqrt( $i ) }; print ($@ ? "error: $@" : $r)'                            
in begin
error: Can't take sqrt of -1 at -e line 1, <> line 1.