$ perl -se 'print $foo' -foo=bar  
Unrecognized switch: -foo=bar  (-h will show valid options).


##</code><code>##

 
perl -e -s 'print $foo' -foo=bar


##</code><code>##

$ perl -es 'print $foo' -foo=bar  
Substitution pattern not terminated at -e line 1.

$ perl -e -s -foo=bar 'print $foo'
Unrecognized switch: -foo=bar  (-h will show valid options).


##</code><code>##

$ perl -e 'print $='     
60