[jmax@gir] ~ $ perl testes.pl
INPUT:
asdf
RESULT:
asdf
INPUT:
#asdf
RESULT:

INPUT:
"#asdF"
RESULT:
"
INPUT:
"lol#asdf"
RESULT:
"lol
INPUT:

[jmax@gir] ~ $ cat testes.pl
print "INPUT:\n";
while (<>) { 
    print "RESULT:\n";
    s/("[^"*])#/$1\\#/;
    s/(?<!\\)#.*//;
    s/("[^"]*)\\#/$1#/;
    print;
    print "INPUT:\n"; 
}