Programming Anti-patterns in Perl

I will spare you with another round of the first half of this post and jump straight to the table of anti-patterns and alternatives in Perl. Check out alternatives.pl for detailed examples. These barely scratch the surface for a rich language like Perl, whose motto itself is TMTOWTDI. My Perl knowledge is still amateurish and these concentrate almost exclusively on the "Accessing memory << Calling a function << Forking a process" guideline. This might be useful for anybody switching from Shell to Perl. So I hope you'll have a lot more to contribute.

30th June, 2011: TimeRatio is the ratio of time taken by Alternative to that by Anti-pattern, as taken from two different trials, using Perl 5.8 on Solaris 10 (Sun T5120). I hope these time ratios will highlight better why especially some of the anti-patterns are to be avoided. My suggestion is to not take these numbers on face value.

Anti-pattern	Alternative	TimeRatio1	TimeRatio2
awk	open, split, close	0.78	0.79
basename	s/.*\///	859.47	872.42
cat	open, close	28.48	28.72
cd	chdir	1588.34	1577.63
cp	use File::Copy "cp"	1.85	1.87
chmod	chmod (Perl)	335.75	343.30
cut	split	306.35	307.05
date	localtime	200.32	214.04
dirname	s/\/^\/*$//	325.41	324.56
echo	print	4008.82	4006.22
find	use File::Find	0.55	0.55
grep	open, grep (Perl), close	2.56	2.57
head	open, break, close	42.12	42.60
hostname	use Sys::Hostname	10361.94	10451.25
id	getpwnam	43.38	43.28
kill	kill (Perl)	55.04	50.84
ln -s	symlink	1010.70	995.73
ls	opendir, closedir	32.87	24.17
mkdir	mkdir (Perl)	13.21	12.93
mkdir -p	use File::Path	9.85	9.87
mv	use File::Copy "move"	32.53	32.65
ping	use Net::Ping	1.04	0.65
ps -elf	use Proc::ProcessTable	3.84	3.84
pwd	$ENV{'PWD'}	3575.62	3742.53
rm	unlink	75.05	74.07
rmdir	rmdir (Perl)	20.13	19.88
rm -r	use File::Path	9.00	9.02
sed	open, s/find/replace/, close	25.54	25.76
sleep	sleep (Perl)	2825.82	2824.30
sort	open, sort (Perl), close	4.31	4.18
tail	open, close	2.71	2.69
touch	open, close	65.41	65.41
umask	umask (Perl)	7749.43	7742.40
uname	use Config	13662.56	13652.62
uniq	open, unless seen, close	2.33	2.35
wc -l	open, close	6.79	6.82