perl (1987) |
python (1991) |
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基础 |
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use strict; |
import os,re,sys |
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$ perl -v |
$ python -V |
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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')" |
; |
\n (newline) |
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语句块 |
{} |
Indent |
注释 |
# comment |
# comment |
多行注释 |
=for |
use triple quote string literal: |
变量和操作符 |
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$v = 1; |
v = 1 |
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赋值 |
($x,$y,$z) = (1,2,3); |
x,y,z = 1,3 |
($x,$y) = ($y,$x); |
x,y = y,x |
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+= -= *= none /= %= **= |
# do not return values: |
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my $x = 1; |
none |
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my $v; |
# in function body: |
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our ($g1,$g2) = (7,8); |
g1,g2 = 7,8 |
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use constant PI => 3.14; |
# uppercase identifiers |
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undef |
None |
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! defined $v |
v == None |
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error under use strict; otherwise undef |
raises NameError |
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1 "" |
True False |
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undef 0 0.0 "" "0" () |
False None 0 0.0 '' [] {} |
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&& || ! |
and or not |
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$x > 0 ? $x : -$x |
x if x > 0 else -x |
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numbers only: == != > < >= <= |
comparison operators are chainable: |
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数学运算 |
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7 + "12" |
7 + int('12') |
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+ - * / none % ** |
+ - * / // % ** |
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取余 |
int ( 13 / 5 ) |
13 // 5 |
13 / 5 |
float(13) / 5 |
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use Math::Trig qw( |
from math import sqrt,exp,log,\ |
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# cpan -i Number::Format |
import math |
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use List::Util qw(min max); |
min(1,3) |
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除0 |
error |
raises ZeroDivisionError |
converted to float; use Math::BigInt to create arbitrary length integers |
becomes arbitrary length integer of type long |
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inf |
raises OverflowError |
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int(rand() * 100) |
import random |
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srand 17; |
import random |
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位操作 |
<< >> & | ^ ~ |
<< >> & | ^ ~ |
0b101010 |
0b101010 |
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"don't say \"no\"" |
'don\'t say "no"' |
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yes |
triple quote literals only |
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double quoted: |
single and double quoted: |
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my $count = 3; |
count = 3 |
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my $fmt = "lorem %s %d %f"; |
'lorem %s %d %f' % ('ipsum',3.7) |
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$word = "amet"; |
‘’’ |
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my $s = "Hello,"; |
s = 'Hello,' |
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my $hbar = "-" x 80; |
hbar = '-' * 80 |
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split(/\s+/,"do re mi fa") |
'do re mi fa'.split() |
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join(" ",qw(do re mi fa)) |
' '.join(['do','re','mi','fa']) |
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uc("lorem") |
'lorem'.upper() |
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字符串strip |
# cpan -i Text::Trim |
' lorem '.strip() |
sprintf("%-10s","lorem") |
'lorem'.ljust(10) |
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length("lorem") |
len('lorem') |
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index("lorem ipsum","ipsum") |
'do re re'.index('re') |
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substr("lorem ipsum",6,5) |
'lorem ipsum'[6:11] |
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can't use index notation with strings: |
'lorem ipsum'[6] |
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chr(65) |
chr(65) |
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/lorem|ipsum/ |
re.compile('lorem|ipsum') |
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char class abbrevs: |
char class abbrevs: |
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if ($s =~ /1999/) { |
if re.search('1999',s): |
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"Lorem" =~ /lorem/i |
re.search('lorem','Lorem',re.I) |
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i m s p x |
re.I re.M re.S re.X |
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my $s = "do re mi mi mi"; |
s = 'do re mi mi mi' |
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$rx = qr/(\d{4})-(\d{2})-(\d{2})/; |
rx = '(\d{4})-(\d{2})-(\d{2})' |
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my $s = "dolor sit amet"; |
s = 'dolor sit amet' |
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"do do" =~ /(\w+) \1/ |
none |
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Time::Piece if use Time::Piece in effect,otherwise tm array |
datetime.datetime |
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use Time::Piece; |
import datetime |
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与epoch转化 |
use Time::Local; |
from datetime import datetime as dt |
当前epoch |
$epoch = time; |
import datetime |
use Time::Piece; |
t.strftime('%Y-%m-%d %H:%M:%S') |
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Tue Aug 23 19:35:19 2011 |
2011-08-23 19:35:59.411135 |
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字符串转为时间strptime |
use Time::Local; |
from datetime import datetime |
# cpan -i Date::Parse |
# pip install python-dateutil |
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Time::Seconds object if use Time::Piece in effect; not meaningful to subtract tm arrays |
datetime.timedelta object |
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use Time::Seconds; |
import datetime |
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Time::Piece has local timezone if created withlocaltime and UTC timezone if created with gmtime; tm arrays have no timezone or offset info |
a datetime object has no timezone information unless a tzinfo object is provided when it is created |
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# cpan -i DateTime |
import time |
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use Time::HiRes qw(gettimeofday); |
t.microsecond |
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a float argument will be truncated to an integer: |
import time |
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eval { |
import signal,time |
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@a = (1,3,4); |
a = [1,4] |
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@a = qw(do re mi); |
none |
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$#a + 1 or |
len(a) |
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!@a |
not a |
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$a[0] |
a[0] |
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$a[0] = "lorem"; |
a[0] = 'lorem' |
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@a = (); |
a = [] |
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use List::Util 'first'; |
a = ['x','y','z','w'] |
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select 3rd and 4th elements: |
select 3rd and 4th elements: |
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@a[1..$#a] |
a[1:] |
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@a = (6,7,8); |
a = [6,8] |
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@a = (6,8); |
a = [6,8] |
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@a = (1,3); |
a = [1,3] |
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@a = (undef) x 10; |
a = [None] * 10 |
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use Storable 'dclone' |
import copy |
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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 |
for $i (1,3) { print "$i\n" } |
for i in [1,3]: |
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none; use range iteration from 0 to $#a and use index to look up value in the loop body |
a = ['do','fa'] |
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for $i (1..1_000_000) { |
range replaces xrange in Python 3: |
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@a = 1..10; |
a = range(1,11) |
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@a = (1,3); |
a = [1,3] |
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@a = qw(b A a B); |
a = ['b','A','a','B'] |
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use List::MoreUtils 'uniq'; |
a = [1,3] |
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7 ~~ @a |
7 in a |
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{1,2} & {2,4} |
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{1,2} | {2,4} |
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{1,3} - {2} |
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map { $_ * $_ } (1,3) |
map(lambda x: x * x,[1,3]) |
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grep { $_ > 1 } (1,3) |
filter(lambda x: x > 1,3]) |
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use List::Util 'reduce'; |
# import needed in Python 3 only |
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# cpan -i List::MoreUtils |
all(i%2 == 0 for i in [1,4]) |
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use List::Util 'shuffle'; |
from random import shuffle,sample |
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# cpan -i List::MoreUtils |
# array of 3 pairs: |
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%d = ( t => 1,f => 0 ); |
d = { 't':1,'f':0 } |
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scalar(keys %d) |
len(d) |
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$d{"t"} |
d['t'] |
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%d = (); |
d = {} |
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exists $d{"y"} |
'y' in d |
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%d = ( 1 => "t",0 => "f" ); |
d = {1: True,0: False} |
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@a = (1,"a","b","c"); |
a = [[1,'a'],[2,'b'],'c']] |
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%d1 = (a=>1,b=>2); |
d1 = {'a':1,'b':2} |
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%to_num = (t=>1,f=>0); |
to_num = {'t':1,'f':0} |
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while ( ($k,$v) = each %d ) { |
for k,v in d.iteritems(): |
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keys %d |
d.keys() |
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my %counts; |
from collections import defaultdict |
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sub add { $_[0] + $_[1] } |
def add(a,b): |
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add(1,2); |
add(1,2) |
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set to undef |
raises TypeError |
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sub my_log { |
import math |
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sub foo { |
def foo(*a): |
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none |
def fequal(x,y,**opts): |
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sub foo { |
not possible |
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sub foo { |
def foo(x,y): |
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return arg or last expression evaluated |
return arg or None |
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sub first_and_second { |
def first_and_second(a): |
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$sqr = sub { $_[0] * $_[0] } |
body must be an expression: |
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lambda invocation |
$sqr->(2) |
sqr(2) |
my $func = \&add; |
func = add |
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use feature state; |
# state not private: |
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sub make_counter { |
# Python 3: |
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none |
def make_counter(): |
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def logcall(f): |
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if ( 0 == $n ) { |
if 0 == n: |
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use feature 'switch'; |
none |
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while ( $i < 100 ) { $i++ } |
while i < 100: |
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for ( $i=0; $i <= 10; $i++ ) { |
none |
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Foreach |
@a = (1..5); foreach (@a) { print "$_\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 [1,3]: print(i) |
last next redo |
break continue none |
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do else elsif for foreach goto if unless until while |
elif else for if while |
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executes following block and returns value of last statement executed |
raises NameError unless a value was assigned to it |
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print "positive\n" if $i > 0; |
none |
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die "bad arg"; |
raise Exception('bad arg') |
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eval { risky }; |
try: |
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$EVAL_ERROR: $@ |
last exception: sys.exc_info()[1] |
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none |
class Bam(Exception): |
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none |
try: |
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none |
acquire_resource() |
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use threads; |
class sleep10(threading.Thread): |
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$thr->join; |
thr.join() |
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print "Hello,World!\n"; |
print('Hello,World!') |
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$line = <STDIN>; |
line = sys.stdin.readline() |
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STDIN STDOUT STDERR |
sys.stdin sys.stdout sys.stderr |
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open my $f,"/etc/hosts"; or |
f = open('/etc/hosts') |
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open my $f,">/tmp/perl_test"; or |
f = open('/tmp/test','w') |
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with open('/tmp/test') as f: |
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close $f; or |
f.close() |
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$line = <$f>; or |
f.readline() |
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while ($line = <$f>) { |
for line in f: |
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chomp $line; |
line = line.rstrip('\r\n') |
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@a = <$f>; |
a = f.readlines() |
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print $f "lorem ipsum"; |
f.write('lorem ipsum') |
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use IO::Handle; |
f.flush() |
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If (-e "/etc/hosts") {print exist;} |
os.path.exists('/etc/hosts') |
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use File::Copy; |
import shutil |
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chmod 0755,"/tmp/foo"; |
os.chmod('/tmp/foo',0755) |
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use File::Temp; |
import tempfile |
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my ($f,$s); |
from StringIO import StringIO |
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use File::Spec; |
os.path.join('/etc','hosts') |
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@L_50_301@ |
use File::Basename; |
os.path.dirname('/etc/hosts') |
use Cwd; |
os.path.abspath('..') |
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use File::Basename; |
for filename in os.listdir('/etc'): |
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use File::Path 'make_path'; |
dirname = '/tmp/foo/bar' |
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# cpan -i File::Copy::Recursive |
import shutil |
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rmdir "/tmp/foodir"; |
os.rmdir('/tmp/foodir') |
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use File::Path 'remove_tree'; |
import shutil |
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-d "/tmp" |
os.path.isdir('/tmp') |
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scalar(@ARGV) |
len(sys.argv)-1 |
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use Getopt::Long; |
import argparse |
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$ENV{"HOME"} |
os.getenv('HOME') |
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exit 0; |
sys.exit(0) |
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$SIG{INT} = sub { |
import signal |
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-x "/bin/ls" |
os.access('/bin/ls',os.X_OK) |
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system("ls -l /tmp") == 0 or |
if os.system('ls -l /tmp'): |
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$path = <>; |
import subprocess |
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my $files = `ls -l /tmp`; or |
import subprocess |
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__________________________________________ |