In addition to the other advice, Perl makes possible neat idioms that I find are quite readable (adding ! to a regex match, while sometimes useful, can help you get lost in a sea of symbols):

while (<IN>) {
   # print if /$pattern/; # normal "grep"
   print unless /$pattern/; # grep -v
}
[download]

$_ is the "default" argument to print, as well as to the pattern match. The "grep -v" line is equivalent to:

print $_ unless $_ =~ /$pattern/;
[download]

HTH

perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); 
+$rose = "smells sweet to degree $n"; *other_name = *rose; print "$oth
+er_name\n"'
[download]