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

# (and similarly with other arrangements of these args)


$ cat junk.pl
#!/usr/bin/perl -s

print "$foo\n" if $foo;

$ perl junk.pl

$ perl junk.pl -foo
1

$ perl junk.pl -foo=bar
1

# (I thought that should have printed "bar", but
# there must be some logical reason why it didn't.)


$ chmod +x junk.pl
$ junk.pl

$ junk.pl -foo
1

$ junk.pl -foo=bar
bar

# at last!


##</code><code>##

$ perl -se 'print "$foo\n" if $foo' -- -foo
1

$ perl -se 'print "$foo\n" if $foo' -- -foo=bar
bar