比较perl+python的优点和缺点

	perl (1987)	python (1991)
基础
模块导入	usestrict;	importos, re, sys
版本查看	$ perl -v	$ python -V
执行脚本	$ perl foo.pl	$ python foo.py
交互模式	$ perl -de 0	$ python
执行语句	$ perl -e 'print("hi\n")'	$ python -c "print('hi')"
语句分隔	;	\n (newline) or ;
语句块	{}	Indent
注释	# comment	# comment
多行注释	=for comment line another line =cut	use triple quote string literal: '''comment line another line'''
变量和操作符
赋值	$v = 1;	v= 1
赋值	($x, $y, $z) = (1, 2, 3); # 3 is discarded: ($x, $y) = (1, 2, 3); # $z set to undef: ($x, $y, $z) = (1, 2);	x,y,z = 1, 2, 3 # raises ValueError: x,y = 1, 2, 3 # raises ValueError: x,y,z = 1, 2
交换	($x, $y) = ($y, $x);	x,y = y, x
操作符	+= -= *=none/= %= **= .= x= &&= ||= ^= <<= >>= &= |= ^=	# do not return values: += -= *= /= //= %= **= += *= &= |= ^= <<= >>= &= |= ^=
自增	my$x = 1; my$y = ++$x; my$z = --$y;	none
局部变量	my$v; my(@a,%d); my$x = 1; my($y,$z) = (2, 3);	# in function body: v = None a,d = [], {} x = 1 y,z = 2, 3
全局变量	our($g1,$g2) = (7, 8); subswap_globals{ ($g1, $g2) = ($g2, $g1); }	g1,g2 = 7, 8 defswap_globals(): globalg1, g2 g1, g2 = g2, g1
常量	useconstantPI => 3.14;	# uppercase identifiers # constant by convention PI = 3.14
空	undef	None
空测试	! defined $v	v ==None v isNone
访问未定义变量	error underuse strict; otherwise undef	raisesNameError
真假	1 ""	True False
假	undef0 0.0 "" "0"()	FalseNone 0 0.0 ''[] {}
逻辑运算	&& || ! lower precedence: and or xor not	and or not
条件	$x > 0 ? $x : -$x	x if x > 0 else-x
比较	numbers only:== != > < >= <= strings:eq ne gt lt ge le	comparison operators are chainable: == != > < >= <=
数学运算
类型转化	7 + "12" 73.9 + ".037" "value: ". 8	7 + int('12') 73.9 + float('.037') 'value: '+ str(8)
算术运算	+ - * /none% **	+ - * / // % **
取余	int( 13 / 5 ) none	13 // 5 q, r = divmod(13, 5)
浮点除法	13 / 5	float(13) / 5 # Python 3: 13 / 5
数学函数	useMath::Trigqw( tan asin acos atan); sqrt exp log sin costan asin acos atan atan2	frommath importsqrt, exp, log, \ sin, cos, tan, asin, acos, atan, atan2
四舍五入	# cpan -i Number::Format useNumber::Format'round'; usePOSIXqw(ceil floor); int($x) round($x, 0) ceil($x) floor($x) abs($x)	importmath int(x) int(round(x)) math.ceil(x) math.floor(x) abs(x)
最大最小	useList::Utilqw(min max); min(1,2,3); max(1,2,3); @a = (1,2,3); min(@a); max(@a);	min(1,2,3) max(1,2,3) min([1,2,3]) max([1,2,3])
除0	error	raisesZeroDivisionError
大整数	converted to float; useMath::BigInt to create arbitrary length integers	becomes arbitrary length integer of typelong
大浮点数	inf	raisesOverflowError
随机数	int(rand() * 100) rand() none	importrandom random.randint(0,99) random.random() random.gauss(0,1)
随机数	srand17; my$sd = srand; srand($sd);	importrandom random.seed(17) sd = random.getstate() random.setstate(sd)
位操作	<< >> & | ^ ~	<< >> & | ^ ~
其他进制	0b101010 052 0x2a	0b101010 052 0x2a
字符串操作
字符串	"don't say \"no\"" 'don\'t say "no"'	'don\'t say "no"' "don't say \"no\"" "don't "'say "no"' '''don't say "no"''' """don't say "no\""""
多行字符串	yes	triple quote literals only
转义	double quoted: \a \b \cx\e \f \n \r \t \xhh\x{hhhh} \oooPerl 5.14:\o{ooo} single quoted: \' \\	single and double quoted: \newline\\ \' \" \a \b \f \n \r \t \v \ooo\xhh Python 3: \uhhhh\Uhhhhhhhh
变量替换	my$count = 3; my$item = "ball"; print"$count ${item}s\n";	count= 3 item= 'ball' print(‘%s %s’ % (count, item))
sprintf	my $fmt = "lorem %s %d %f"; sprintf($fmt,"ipsum", 13, 3.7)	'lorem %s %d %f'% ('ipsum', 13, 3.7) fmt = 'lorem {0} {1} {2}' fmt.format('ipsum', 13, 3.7)
here document	$word ="amet"; $s = <<EOF; lorem ipsum dolor sit $word EOF	‘’’ ‘’’
字符串连接	my$s = "Hello, "; my$s2 = $s . "World!";	s= 'Hello, ' s2 = s + 'World!' juxtaposition can be used to concatenate literals: s2 = 'Hello, ' "World!"
字符串复制	my$hbar = "-"x 80;	hbar= '-'* 80
字符串分隔	split(/\s+/,"do re mi fa") split(/\s+/,"do re mi fa", 2) split(/(\s+)/,"do re mi fa"); split(//,"abcd")	'do re mi fa'.split() 'do re mi fa'.split(None, 1) re.split('(\s+)','do re mi fa') list('abcd')
字符串连接	join(" ",qw(do re mi fa))	' '.join(['do','re','mi','fa'])
字符串大小写	uc("lorem") lc("LOREM") ucfirst("lorem")	'lorem'.upper() 'LOREM'.lower() 'lorem'.capitalize()
字符串strip	# cpan -i Text::Trim useText::Trim; trim " lorem " ltrim " lorem" rtrim "lorem "	' lorem '.strip() ' lorem'.lstrip() 'lorem '.rstrip()
字符串格式化	sprintf("%-10s","lorem") sprintf("%10s","lorem")	'lorem'.ljust(10) 'lorem'.rjust(10)
字符串长度	length("lorem")	len('lorem')
字符串index	index("lorem ipsum","ipsum") rindex("do re re","re") return-1 if not found	'do re re'.index('re') 'do re re'.rindex('re') raiseValueError if not found
子字符串	substr("lorem ipsum", 6, 5)	'lorem ipsum'[6:11]
访问字符串中字母	can't use index notation with strings: substr("lorem ipsum", 6, 1)	'lorem ipsum'[6]
字母数字转化	chr(65) ord("A")	chr(65) ord('A')
正则表达式
字符串或	/lorem|ipsum/ qr(/etc/hosts)	re.compile('lorem|ipsum') none
特殊字符	char class abbrevs: . \d \D \h \H \s \S \v \V \w \W anchors:^ $ \A \b \B \z \Z	char class abbrevs: . \d \D \s \S \w \W anchors:^ $ \A \b \B \Z
正则表达式匹配	if($s =~ /1999/) { print"party!\n"; }	ifre.search('1999', s): print('party!')
忽略大小写	"Lorem"=~ /lorem/i	re.search('lorem','Lorem', re.I)
选项	i m s p x	re.I re.M re.S re.X
替换	my$s= "do re mi mi mi"; $s =~ s/mi/ma/g;	s= 'do re mi mi mi' s = re.compile('mi').sub('ma', s)
group	$rx =qr/(\d{4})-(\d{2})-(\d{2})/; "2010-06-03"=~ $rx; ($yr, $mo, $dy) = ($1, $2, $3);	rx= '(\d{4})-(\d{2})-(\d{2})' m = re.search(rx, '2010-06-03') yr,mo,dy = m.groups()
findall	my$s= "dolor sit amet"; @a = $s =~ m/\w+/g;	s= 'dolor sit amet' a = re.findall('\w+', s)
匹配引用	"do do"=~ /(\w+) \1/ my$s= "do re"; $s =~ s/(\w+) (\w+)/$2 $1/;	none rx = re.compile('(\w+) (\w+)') rx.sub(r'\2 \1','do re')
日期时间
日期时间类型	Time::Pieceif use Time::Piece in effect, otherwise tm array	datetime.datetime
当前日期时间	useTime::Piece; my$t= localtime(time); my$utc= gmtime(time);	importdatetime t = datetime.datetime.now() utc = datetime.datetime.utcnow()
与epoch转化	useTime::Local; useTime::Piece; my$epoch= timelocal($t); my$t2= localtime(1304442000);	fromdatetime importdatetime asdt epoch= int(t.strftime("%s")) t2 = dt.fromtimestamp(1304442000)
当前epoch	$epoch =time;	importdatetime t = datetime.datetime.now() epoch= int(t.strftime("%s"))
strftime	useTime::Piece; $t = localtime(time); $fmt = "%Y-%m-%d %H:%M:%S"; print$t->strftime($fmt);	t.strftime('%Y-%m-%d %H:%M:%S')
默认格式	Tue Aug 23 19:35:19 2011	2011-08-23 19:35:59.411135
字符串转为时间strptime	useTime::Local; useTime::Piece; $s = "2011-05-03 10:00:00"; $fmt = "%Y-%m-%d %H:%M:%S"; $t = Time::Piece->strptime($s,$fmt);	fromdatetime importdatetime s = '2011-05-03 10:00:00' fmt = '%Y-%m-%d %H:%M:%S' t = datetime.strptime(s, fmt)
解析日期	# cpan -i Date::Parse useDate::Parse; $epoch = str2time("July 7, 1999");	# pip install python-dateutil importdateutil.parser s = 'July 7, 1999' t = dateutil.parser.parse(s)
时间差	Time::Secondsobject if use Time::Piece in effect; not meaningful to subtract tm arrays	datetime.timedeltaobject
时间运算	useTime::Seconds; $now = localtime(time); $now += 10 * ONE_MINUTE() + 3;	importdatetime delta= datetime.timedelta( minutes=10, seconds=3) t = datetime.datetime.now() + delta
时区	Time::Piecehas local timezone if created withlocaltime and UTC timezone if created with gmtime;tm arrays have no timezone or offset info	adatetime object has no timezone information unless a tzinfoobject is provided when it is created
timezone name; offset from UTC; 是否夏令时	# cpan -i DateTime useDateTime; useDateTime::TimeZone; $dt = DateTime->now(); $tz = DateTime::TimeZone->new( name=>"local"); $tz->name; $tz->offset_for_datetime($dt) / 3600; $tz->is_dst_for_datetime($dt);	importtime tm = time.localtime() time.tzname[tm.tm_isdst] (time.timezone / -3600) + tm.tm_isdst tm.tm_isdst
microseconds	useTime::HiResqw(gettimeofday); ($sec, $usec) = gettimeofday;	t.microsecond
sleep	a float argument will be truncated to an integer: sleep1;	importtime time.sleep(0.5)
timeout	eval{ $SIG{ALRM}=sub{die"timeout!";}; alarm5; sleep10; }; alarm0;	importsignal, time classTimeout(Exception):pass deftimeout_handler(signo, fm): raiseTimeout() signal.signal(signal.SIGALRM, timeout_handler) try: signal.alarm(5) time.sleep(10) exceptTimeout: pass signal.alarm(0)
数组
定义	@a= (1, 2, 3, 4);	a= [1, 2, 3, 4]
quote words	@a= qw(do re mi);	none
长度	$#a+ 1 or scalar(@a)	len(a)
空测试	!@a	nota
使用	$a[0]	a[0]
更新	$a[0] ="lorem";	a[0] ='lorem'
越界访问	@a= (); evaluates asundef: $a[10]; increases array size to 11: $a[10] ="lorem";	a= [] raisesIndexError: a[10] raisesIndexError: a[10] = 'lorem'
index	useList::Util'first'; @a = qw(x y z w); $i = first {$a[$_]eq "y"} (0..$#a);	a= ['x','y','z','w'] i = a.index('y')
子数组	select 3rd and 4th elements: @a[2..3] splice(@a, 2, 2)	select 3rd and 4th elements: a[2:4] none
子数组	@a[1..$#a]	a[1:]
添加删除	@a= (6,7,8); push@a, 9; pop@a;	a= [6,7,8] a.append(9) a.pop()
插入删除	@a= (6,7,8); unshift@a, 5; shift@a;	a= [6,7,8] a.insert(0,5) a.pop(0)
数组连接	@a= (1,2,3); @a2 = (@a,(4,5,6)); push@a, (4,5,6);	a= [1,2,3] a2 = a + [4,5,6] a.extend([4,5,6])
初始化	@a= (undef)x 10;	a = [None] * 10 a = [None fori in range(0, 10)]
浅拷贝深拷贝	useStorable'dclone' my@a = (1,2,[3,4]); my$a2 = \@a; my@a3 = @a; my@a4 = @{dclone(\@a)};	importcopy a = [1,2,[3,4]] a2 = a a3 = list(a) a4 = copy.deepcopy(a)
数组作为函数参数	each element passed as separate argument; use reference to pass array as single argument	parameter contains address copy
遍历	for$i (1, 2, 3) { print"$i\n" }	fori in[1,2,3]: print(i)
遍历	none; use range iteration from0 to $#a and use index to look up value in the loop body	a= ['do','re','mi','fa'] fori, s inenumerate(a): print('%s at index %d'% (s, i))
range	for$i (1..1_000_000) { code }	rangereplaces xrange in Python 3: fori in xrange(1, 1000001): code
range数组	@a= 1..10;	a= range(1, 11) Python 3: a = list(range(1, 11))
翻转	@a= (1,2,3); reverse@a; @a = reverse@a;	a= [1,2,3] a[::-1] a.reverse()
排序	@a= qw(b A a B); sort@a; @a = sort@a; sort{ lc($a)cmplc($b) }@a;	a= ['b','A','a','B'] sorted(a) a.sort() a.sort(key=str.lower)
去重复	useList::MoreUtils'uniq'; my@a = (1,2,2,3); my@a2 = uniq @a; @a = uniq @a;	a= [1,2,2,3] a2 = list(set(a)) a = list(set(a))
是否存在于数组	7 ~~@a	7 in a
集合交集		{1,2} & {2,3,4}
集合或		{1,2} | {2,3,4}
集合运算		{1,2,3} - {2} {1,2} ^ {2,3,4}
map	map{ $_ * $_ } (1,2,3)	map(lambdax: x * x, [1,2,3]) # or use list comprehension: [x*x for x in [1,2,3]]
filter	grep{ $_ > 1 } (1,2,3)	filter(lambdax: x > 1, [1,2,3]) # or use list comprehension: [x for x in [1,2,3] if x > 1]
reduce	useList::Util'reduce'; reduce { $x + $y } 0, (1,2,3)	# import needed in Python 3 only fromfunctools import reduce reduce(lambdax, y: x+y, [1,2,3], 0)
All/any	# cpan -i List::MoreUtils useList::MoreUtilsqw(all any); all { $_ % 2 == 0 } (1,2,3,4) any { $_ % 2 == 0 } (1,2,3,4)	all(i%2 == 0fori in[1,2,3,4]) any(i%2 == 0fori in[1,2,3,4])
shuffle and sample	useList::Util'shuffle'; @a = (1, 2, 3, 4); shuffle(@a); none	fromrandom importshuffle, sample a = [1, 2, 3, 4] shuffle(a) sample(a, 2)
zip	# cpan -i List::MoreUtils useList::MoreUtils'zip'; @nums= (1, 2, 3); @lets= qw(a b c); # flat array of 6 elements: @a = zip @nums,@lets;	# array of 3 pairs: a = zip([1,2,3], ['a','b','c'])
字典对象
定义	%d= ( t=> 1, f=> 0 );	d= { 't':1,'f':0 }
size	scalar(keys%d)	len(d)
lookup	$d{"t"}	d['t']
out-of-bounds behavior	%d= (); evaluates asundef: $d{"lorem"}; adds key/value pair: $d{"lorem"} = "ipsum";	d= {} raisesKeyError: d['lorem'] adds key/value pair: d['lorem'] ='ipsum'
is key present	exists$d{"y"}	'y'in d
delete entry	%d= ( 1 => "t", 0 =>"f"); delete$d{1};	d= {1: True, 0:False} deld[1]
from array of pairs, from even length array	@a= (1,"a",2,"b",3,"c"); %d = @a;	a= [[1,'a'], [2,'b'], [3,'c']] d = dict(a) a = [1,'a',2,'b',3,'c'] d = dict(zip(a[::2], a[1::2]))
merge	%d1= (a=>1,b=>2); %d2 = (b=>3,c=>4); %d1 = (%d1,%d2);	d1= {'a':1,'b':2} d2 = {'b':3,'c':4} d1.update(d2) # {'a': 1, 'c': 4, 'b': 3}
invert	%to_num= (t=>1,f=>0); %to_let= reverse%to_num;	to_num= {'t':1,'f':0} # dict comprehensions added in 2.7: to_let= {v:k fork, v into_num.items()}
iteration	while( ($k, $v) = each%d ) { code }	fork, v ind.iteritems(): code Python 3: fork, v ind.items(): code
keys and values as arrays	keys%d values%d	d.keys() d.values() Python 3: list(d.keys()) list(d.values())
default value, computed value	my%counts; $counts{'foo'} += 1 define a tied hash for computed values and defaults other than zero or empty string	fromcollections importdefaultdict counts= defaultdict(lambda: 0) counts['foo'] += 1 classFactorial(dict): def__missing__(self, k): ifk > 1: returnk * self[k-1] else: return1 factorial= Factorial()
函数
函数申明	subadd { $_[0] +$_[1] } subadd { my($a,$b) =@_; $a + $b; }	defadd(a, b): returna+b
函数调用	add(1, 2); parens are optional: add 1, 2;	add(1, 2)
参数丢失	set toundef	raisesTypeError
参数默认值	submy_log{ my$x = shift; my$base = shift// 10; log($x)/log($base); } my_log(42); my_log(42, exp(1));	importmath defmy_log(x, base=10): returnmath.log(x)/math.log(base) my_log(42) my_log(42, math.e)
变长参数	subfoo { if( @_>= 1 ) { print"first: $_[0]\n"; } if( @_>= 2 ) { print"last: $_[-1]\n"; } }	deffoo(*a): if len(a) >= 1: print('first: '+ str(a[0])) if len(a) >= 2: print('last: '+ str(a[-1]))
命名参数	none	deffequal(x, y, **opts): eps = opts.get('eps')or0.01 return abs(x - y) < eps fequal(1.0, 1.001) fequal(1.0, 1.001, eps=0.1**10)
pass number or string by reference	subfoo { $_[0] += 1; $_[1] .="ly"; } my$n = 7; my$s = "hard"; foo($n, $s);	not possible
pass array or dictionary by reference	subfoo { $_[0][2] = 5; $_[1]{"f"} = -1; } my@a = (1,2,3); my%d = ("t"=> 1,"f"=> 0); foo(\@a, \%d);	deffoo(x, y): x[2] = 5 y['f'] = -1 a = [1,2,3] d = {'t':1,'f':0} foo(a, d)
return value	returnarg or last expression evaluated	returnarg or None
multiple return values	subfirst_and_second{ return($_[0],$_[1]); } @a = (1,2,3); ($x, $y) = first_and_second(@a);	deffirst_and_second(a): returna[0], a[1] x,y = first_and_second([1,2,3])
lambda declaration	$sqr =sub{ $_[0] *$_[0] }	body must be an expression: sqr = lambdax: x * x
lambda invocation	$sqr->(2)	sqr(2)
function reference	my$func = \&add;	func= add
function with private state	usefeaturestate; subcounter{ state $i = 0; ++$i; } printcounter() . "\n";	# state not private: defcounter(): counter.i += 1 returncounter.i counter.i = 0 print(counter())
closure	submake_counter{ my$i = 0; returnsub { ++$i }; } my$nays = make_counter; print$nays->() . "\n";	# Python 3: defmake_counter(): i = 0 defcounter(): nonlocal i i += 1 returni returncounter nays = make_counter()
generator	none	defmake_counter(): i = 0 while True: i += 1 yieldi nays= make_counter() print(nays.next())
decorator		def logcall(f): def wrapper(*a, **opts): print('calling ' + f.__name__) f(*a, **opts) print('called ' + f.__name__) return wrapper @logcall def square(x): return x * x square(5)
流程控制
if	if( 0 == $n ) { print"no hits\n" } elsif( 1 == $n ) { print"one hit\n" } else{ print"$n hits\n" }	if0 == n: print('no hits') elif1 == n: print('one hit') else: print(str(n) + ' hits')
switch	usefeature'switch'; given ($n) { when (0) { print"no hits\n"; } when (1) { print"one hit\n"; } default { print"$n hits\n"; } }	none
while	while( $i < 100 ) { $i++ }	whilei < 100: i += 1
c-style for	for( $i=0; $i <= 10; $i++ ) { print"$i\n"; }	none
Foreach	@a = (1..5); foreach (@a) { print "$_\n"; } @a = (1..5); for (@a) { print "$_\n" }	a = ['do', 're', 'mi', 'fa'] for i, s in enumerate(a): print('%s at index %d' % (s, i)) for i in [1,2,3]: print(i)
break, continue, redo	last next redo	break continuenone
control structure keywords	do else elsif for foreach goto if unless until while	elif else for if while
what do does	executes following block and returns value of last statement executed	raisesNameError unless a value was assigned to it
statement modifiers	print"positive\n"if $i > 0; print"nonzero\n"unless $i == 0;	none
raise exception	die"bad arg";	raiseException('bad arg')
catch exception	eval{ risky }; if($@) { print"risky failed: $@\n"; }	try: risky() except: print('risky failed')
global variable for last exception	$EVAL_ERROR: $@ $OS_ERROR:$! $CHILD_ERROR: $?	last exception:sys.exc_info()[1]
define exception	none	classBam(Exception): def__init__(self): super(Bam,self).__init__('bam!')
catch exception by type	none	try: raiseBam() exceptBam ase: print(e)
finally/ensure	none	acquire_resource() try: risky() finally: release_resource()
start thread	usethreads; $func = sub{ sleep10 }; $thr = threads->new($func);	classsleep10(threading.Thread): defrun(self): time.sleep(10) thr = sleep10() thr.start()
wait on thread	$thr->join;	thr.join()
文件和输出
print to standard output	print"Hello, World!\n";	print('Hello, World!')
read from standard input	$line = <STDIN>;	line= sys.stdin.readline()
standard file handles	STDIN STDOUT STDERR	sys.stdin sys.stdout sys.stderr
open file	openmy $f, "/etc/hosts";or openFILE, "/etc/hosts";	f= open('/etc/hosts')
open file for writing	openmy $f, ">/tmp/perl_test";or openFILE, ">/tmp/perl_test";	f= open('/tmp/test','w')
open file for append		with open('/tmp/test')asf: f.write('lorem ipsum\n')
close file	close$f; or closeFILE;	f.close()
read line	$line = <$f>;or $line = <FILE>;	f.readline()
iterate over file by line	while($line = <$f>) {	forline inf:
chomp	chomp$line;	line= line.rstrip('\r\n')
read entire file into array or string	@a= <$f>; $s = do { local $/; <$f> };	a= f.readlines() s = f.read()
write to file	print$f "lorem ipsum";	f.write('lorem ipsum')
flush file handle	useIO::Handle; $f->flush();	f.flush()
file test, regular file test	If (-e"/etc/hosts") {print exist;} -f"/etc/hosts"	os.path.exists('/etc/hosts') os.path.isfile('/etc/hosts')
copy file, remove file, rename file	useFile::Copy; copy("/tmp/foo","/tmp/bar"); unlink"/tmp/foo"; move("/tmp/bar","/tmp/foo"); unlink();	importshutil shutil.copy('/tmp/foo','/tmp/bar') os.remove('/tmp/foo') shutil.move('/tmp/bar','/tmp/foo') os.remove()
set file permissions	chmod0755, "/tmp/foo";	os.chmod('/tmp/foo', 0755)
temporary file	useFile::Temp; $f = File::Temp->new(); print$f "lorem ipsum\n"; close $f; print"tmp file: "; print$f->filename . "\n";	importtempfile f = tempfile.NamedTemporaryFile( prefix='foo') f.write('lorem ipsum\n') f.close() print("tmp file: %s"% f.name)
in memory file	my($f,$s); open($f,">", \$s); print$f "lorem ipsum\n"; $s;	fromStringIO importStringIO f = StringIO() f.write('lorem ipsum\n') s = f.getvalue() Python 3 movedStringIO to the iomodule
目录操作
build pathname	useFile::Spec; File::Spec->catfile("/etc","hosts")	os.path.join('/etc','hosts')
dirname and basename	useFile::Basename; printdirname("/etc/hosts"); printbasename("/etc/hosts");	os.path.dirname('/etc/hosts') os.path.basename('/etc/hosts')
absolute pathname	useCwd; Cwd::abs_path("..")	os.path.abspath('..')
iterate over directory by file	useFile::Basename; while( </etc/*>) { printbasename($_) . "\n"; }	forfilename inos.listdir('/etc'): print(filename)
make directory	useFile::Path'make_path'; make_path "/tmp/foo/bar";	dirname= '/tmp/foo/bar' if notos.path.isdir(dirname): os.makedirs(dirname)
recursive copy	# cpan -i File::Copy::Recursive useFile::Copy::Recursive'dircopy'; dircopy "/tmp/foodir", "/tmp/bardir";	importshutil shutil.copytree('/tmp/foodir', '/tmp/bardir')
remove empty directory	rmdir"/tmp/foodir";	os.rmdir('/tmp/foodir')
remove directory and contents	useFile::Path'remove_tree'; remove_tree "/tmp/foodir";	importshutil shutil.rmtree('/tmp/foodir')
directory test	-d"/tmp"	os.path.isdir('/tmp')
命令行操作
command line args, script name	scalar(@ARGV) $ARGV[0]$ARGV[1]etc $0	len(sys.argv)-1 sys.argv[1] sys.argv[2] etc sys.argv[0]
getopt	useGetopt::Long; my($src,$help); subusage{ print"usage: $0 --f SRC\n"; exit-1; } GetOptions("file=s"=> \$src, "help"=> \$help); usage if$help;	importargparse parser= argparse.ArgumentParser() parser.add_argument('--file','-f', dest='file') args= parser.parse_args() src = args.file
get and set environment variable	$ENV{"HOME"} $ENV{"PATH") = "/bin";	os.getenv('HOME') os.environ['PATH'] ='/bin'
exit	exit0;	sys.exit(0)
set signal handller	$SIG{INT} =sub{ die"exiting…\n"; };	importsignal defhandler(signo, frame): print('exiting…') exit-1 signal.signal(signal.SIGINT, handler)
executable test	-x"/bin/ls"	os.access('/bin/ls', os.X_OK)
external command	system("ls -l /tmp") == 0 or die"ls failed";	ifos.system('ls -l /tmp'): raiseException('ls failed')
escaped external command	$path = <>; chomp($path); system("ls","-l", $path) == 0or die"ls failed";	importsubprocess cmd = ['ls','-l','/tmp'] ifsubprocess.call(cmd): raiseException('ls failed')
backticks	my$files = `ls -l /tmp`;or my$files = qx(ls);	importsubprocess cmd = ['ls','-l','/tmp'] files= subprocess.check_output(cmd)
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