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perl (1987)
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python (1991)
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基础
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模块导入
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use strict;
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import os, re, sys
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版本查看
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$ perl -v
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$ python -V
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执行脚本
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$ perl foo.pl
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$ python foo.py
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交互模式
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$ perl -de 0
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$ python
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执行语句
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$ perl -e 'print("hi\n")'
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$ python -c "print('hi')"
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语句分隔
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;
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\n (newline)
or ;
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语句块
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{}
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Indent
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注释
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# comment
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# comment
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多行注释
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=for
comment line
another line
=cut
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use triple quote string literal:
'''comment line
another line'''
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变量和操作符
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赋值
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$v = 1;
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v = 1
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赋值
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($x, $y, $z) = (1, 2, 3);
# 3 is discarded:
($x, $y) = (1, 2, 3);
# $z set to undef:
($x, $y, $z) = (1, 2);
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x, y, z = 1, 2, 3
# raises ValueError:
x, y = 1, 2, 3
# raises ValueError:
x, y, z = 1, 2
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交换
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($x, $y) = ($y, $x);
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x, y = y, x
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操作符
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+= -= *= none /= %= **=
.= x=
&&= ||= ^=
<<= >>= &= |= ^=
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# do not return values:
+= -= *= /= //= %= **=
+= *=
&= |= ^=
<<= >>= &= |= ^=
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自增
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my $x = 1;
my $y = ++$x;
my $z = --$y;
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none
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局部变量
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my $v;
my (@a, %d);
my $x = 1;
my ($y, $z) = (2, 3);
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# in function body:
v = None
a, d = [], {}
x = 1
y, z = 2, 3
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全局变量
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our ($g1, $g2) = (7, 8);
sub swap_globals {
($g1, $g2) = ($g2, $g1);
}
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g1, g2 = 7, 8
def swap_globals():
global g1, g2
g1, g2 = g2, g1
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常量
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use constant PI => 3.14;
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# uppercase identifiers
# constant by convention
PI = 3.14
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空
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undef
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None
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空测试
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! defined $v
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v == None
v is None
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访问未定义变量
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error under use strict; otherwise undef
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raises NameError
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真假
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1 ""
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True False
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假
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undef 0 0.0 "" "0" ()
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False None 0 0.0 '' [] {}
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逻辑运算
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&& || !
lower precedence:
and or xor not
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and or not
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条件
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$x > 0 ? $x : -$x
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x if x > 0 else -x
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比较
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numbers only: == != > < >= <=
strings: eq ne gt lt ge le
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comparison operators are chainable:
== != > < >= <=
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数学运算
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类型转化
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7 + "12"
73.9 + ".037"
"value: " . 8
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7 + int('12')
73.9 + float('.037')
'value: ' + str(8)
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算术运算
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+ - * / none % **
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+ - * / // % **
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取余
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int ( 13 / 5 )
none
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13 // 5
q, r = divmod(13, 5)
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浮点除法
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13 / 5
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float(13) / 5
# Python 3:
13 / 5
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数学函数
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use Math::Trig qw(
tan asin acos atan);
sqrt exp log sin cos tan asin acos atan atan2
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from math import sqrt, exp, log, \
sin, cos, tan, asin, acos, atan, atan2
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四舍五入
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# cpan -i Number::Format
use Number::Format 'round';
use POSIX qw(ceil floor);
int($x)
round($x, 0)
ceil($x)
floor($x)
abs($x)
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import math
int(x)
int(round(x))
math.ceil(x)
math.floor(x)
abs(x)
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最大最小
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use List::Util qw(min max);
min(1,2,3);
max(1,2,3);
@a = (1,2,3);
min(@a);
max(@a);
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min(1,2,3)
max(1,2,3)
min([1,2,3])
max([1,2,3])
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除0
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error
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raises ZeroDivisionError
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大整数
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converted to float; use Math::BigInt to create arbitrary length integers
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becomes arbitrary length integer of type long
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大浮点数
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inf
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raises OverflowError
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随机数
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int(rand() * 100)
rand()
none
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import random
random.randint(0,99)
random.random()
random.gauss(0,1)
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随机数
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srand 17;
my $sd = srand;
srand($sd);
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import random
random.seed(17)
sd = random.getstate()
random.setstate(sd)
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位操作
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<< >> & | ^ ~
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<< >> & | ^ ~
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其他进制
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0b101010
052
0x2a
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0b101010
052
0x2a
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字符串操作
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字符串
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"don't say \"no\""
'don\'t say "no"'
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'don\'t say "no"'
"don't say \"no\""
"don't " 'say "no"'
'''don't say "no"'''
"""don't say "no\""""
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多行字符串
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yes
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triple quote literals only
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转义
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double quoted:
\a \b \cx \e \f \n \r \t \xhh \x{hhhh} \ooo Perl 5.14: \o{ooo}
single quoted:
\' \\
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single and double quoted:
\newline \\ \' \" \a \b \f \n \r \t \v \ooo \xhh
Python 3:
\uhhhh \Uhhhhhhhh
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变量替换
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my $count = 3;
my $item = "ball";
print "$count ${item}s\n";
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count = 3
item = 'ball'
print(‘%s %s’ % (count, item))
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sprintf
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my $fmt = "lorem %s %d %f";
sprintf($fmt, "ipsum", 13, 3.7)
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'lorem %s %d %f' % ('ipsum', 13, 3.7)
fmt = 'lorem {0} {1} {2}'
fmt.format('ipsum', 13, 3.7)
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here document
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$word = "amet";
$s = <<EOF;
lorem ipsum
dolor sit $word
EOF
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‘’’
‘’’
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字符串连接
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my $s = "Hello, ";
my $s2 = $s . "World!";
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s = 'Hello, '
s2 = s + 'World!'
juxtaposition can be used to concatenate literals:
s2 = 'Hello, ' "World!"
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字符串复制
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my $hbar = "-" x 80;
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hbar = '-' * 80
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字符串分隔
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split(/\s+/, "do re mi fa")
split(/\s+/, "do re mi fa", 2)
split(/(\s+)/, "do re mi fa");
split(//, "abcd")
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'do re mi fa'.split()
'do re mi fa'.split(None, 1)
re.split('(\s+)', 'do re mi fa')
list('abcd')
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字符串连接
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join(" ", qw(do re mi fa))
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' '.join(['do', 're', 'mi', 'fa'])
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字符串大小写
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uc("lorem")
lc("LOREM")
ucfirst("lorem")
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'lorem'.upper()
'LOREM'.lower()
'lorem'.capitalize()
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字符串strip
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# cpan -i Text::Trim
use Text::Trim;
trim " lorem "
ltrim " lorem"
rtrim "lorem "
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' lorem '.strip()
' lorem'.lstrip()
'lorem '.rstrip()
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字符串格式化
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sprintf("%-10s", "lorem")
sprintf("%10s", "lorem")
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'lorem'.ljust(10)
'lorem'.rjust(10)
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字符串长度
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length("lorem")
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len('lorem')
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字符串index
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index("lorem ipsum", "ipsum")
rindex("do re re", "re")
return -1 if not found
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'do re re'.index('re')
'do re re'.rindex('re')
raise ValueError if not found
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子字符串
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substr("lorem ipsum", 6, 5)
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'lorem ipsum'[6:11]
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访问字符串中字母
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can't use index notation with strings:
substr("lorem ipsum", 6, 1)
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'lorem ipsum'[6]
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字母数字转化
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chr(65)
ord("A")
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chr(65)
ord('A')
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正则表达式
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字符串或
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/lorem|ipsum/
qr(/etc/hosts)
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re.compile('lorem|ipsum')
none
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特殊字符
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char class abbrevs:
. \d \D \h \H \s \S \v \V \w \W
anchors: ^ $ \A \b \B \z \Z
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char class abbrevs:
. \d \D \s \S \w \W
anchors: ^ $ \A \b \B \Z
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正则表达式匹配
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if ($s =~ /1999/) {
print "party!\n";
}
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if re.search('1999', s):
print('party!')
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忽略大小写
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"Lorem" =~ /lorem/i
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re.search('lorem', 'Lorem', re.I)
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选项
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i m s p x
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re.I re.M re.S re.X
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替换
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my $s = "do re mi mi mi";
$s =~ s/mi/ma/g;
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s = 'do re mi mi mi'
s = re.compile('mi').sub('ma', s)
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group
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$rx = qr/(\d{4})-(\d{2})-(\d{2})/;
"2010-06-03" =~ $rx;
($yr, $mo, $dy) = ($1, $2, $3);
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rx = '(\d{4})-(\d{2})-(\d{2})'
m = re.search(rx, '2010-06-03')
yr, mo, dy = m.groups()
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findall
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my $s = "dolor sit amet";
@a = $s =~ m/\w+/g;
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s = 'dolor sit amet'
a = re.findall('\w+', s)
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匹配引用
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"do do" =~ /(\w+) \1/
my $s = "do re";
$s =~ s/(\w+) (\w+)/$2 $1/;
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none
rx = re.compile('(\w+) (\w+)')
rx.sub(r'\2 \1', 'do re')
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日期时间
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日期时间类型
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Time::Piece if use Time::Piece in effect, otherwise tm array
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datetime.datetime
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当前日期时间
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use Time::Piece;
my $t = localtime(time);
my $utc = gmtime(time);
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import datetime
t = datetime.datetime.now()
utc = datetime.datetime.utcnow()
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与epoch转化
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use Time::Local;
use Time::Piece;
my $epoch = timelocal($t);
my $t2 = localtime(1304442000);
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from datetime import datetime as dt
epoch = int(t.strftime("%s"))
t2 = dt.fromtimestamp(1304442000)
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当前epoch
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$epoch = time;
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import datetime
t = datetime.datetime.now()
epoch = int(t.strftime("%s"))
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strftime
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use Time::Piece;
$t = localtime(time);
$fmt = "%Y-%m-%d %H:%M:%S";
print $t->strftime($fmt);
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t.strftime('%Y-%m-%d %H:%M:%S')
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默认格式
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Tue Aug 23 19:35:19 2011
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2011-08-23 19:35:59.411135
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字符串转为时间strptime
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use Time::Local;
use Time::Piece;
$s = "2011-05-03 10:00:00";
$fmt = "%Y-%m-%d %H:%M:%S";
$t = Time::Piece->strptime($s,$fmt);
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from datetime import datetime
s = '2011-05-03 10:00:00'
fmt = '%Y-%m-%d %H:%M:%S'
t = datetime.strptime(s, fmt)
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解析日期
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# cpan -i Date::Parse
use Date::Parse;
$epoch = str2time("July 7, 1999");
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# pip install python-dateutil
import dateutil.parser
s = 'July 7, 1999'
t = dateutil.parser.parse(s)
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时间差
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Time::Seconds object if use Time::Piece in effect; not meaningful to subtract tm arrays
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datetime.timedelta object
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时间运算
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use Time::Seconds;
$now = localtime(time);
$now += 10 * ONE_MINUTE() + 3;
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import datetime
delta = datetime.timedelta(
minutes=10,
seconds=3)
t = datetime.datetime.now() + delta
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时区
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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
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a datetime object has no timezone information unless a tzinfo object is provided when it is created
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timezone name; offset from UTC; 是否夏令时
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# cpan -i DateTime
use DateTime;
use DateTime::TimeZone;
$dt = DateTime->now();
$tz = DateTime::TimeZone->new(
name=>"local");
$tz->name;
$tz->offset_for_datetime($dt) /
3600;
$tz->is_dst_for_datetime($dt);
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import time
tm = time.localtime()
time.tzname[tm.tm_isdst]
(time.timezone / -3600) + tm.tm_isdst
tm.tm_isdst
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microseconds
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use Time::HiRes qw(gettimeofday);
($sec, $usec) = gettimeofday;
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t.microsecond
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sleep
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a float argument will be truncated to an integer:
sleep 1;
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import time
time.sleep(0.5)
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timeout
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eval {
$SIG{ALRM}= sub {die "timeout!";};
alarm 5;
sleep 10;
};
alarm 0;
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import signal, time
class Timeout(Exception): pass
def timeout_handler(signo, fm):
raise Timeout()
signal.signal(signal.SIGALRM,
timeout_handler)
try:
signal.alarm(5)
time.sleep(10)
except Timeout:
pass
signal.alarm(0)
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数组
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定义
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@a = (1, 2, 3, 4);
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a = [1, 2, 3, 4]
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quote words
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@a = qw(do re mi);
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none
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长度
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$#a + 1 or
scalar(@a)
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len(a)
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空测试
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!@a
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not a
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使用
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$a[0]
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a[0]
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更新
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$a[0] = "lorem";
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a[0] = 'lorem'
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越界访问
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@a = ();
evaluates as undef:
$a[10];
increases array size to 11:
$a[10] = "lorem";
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a = []
raises IndexError:
a[10]
raises IndexError:
a[10] = 'lorem'
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index
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use List::Util 'first';
@a = qw(x y z w);
$i = first {$a[$_] eq "y"} (0..$#a);
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a = ['x', 'y', 'z', 'w']
i = a.index('y')
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子数组
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select 3rd and 4th elements:
@a[2..3]
splice(@a, 2, 2)
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select 3rd and 4th elements:
a[2:4]
none
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子数组
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@a[1..$#a]
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a[1:]
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添加删除
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@a = (6,7,8);
push @a, 9;
pop @a;
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a = [6,7,8]
a.append(9)
a.pop()
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插入删除
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@a = (6,7,8);
unshift @a, 5;
shift @a;
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a = [6,7,8]
a.insert(0,5)
a.pop(0)
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数组连接
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@a = (1,2,3);
@a2 = (@a,(4,5,6));
push @a, (4,5,6);
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a = [1,2,3]
a2 = a + [4,5,6]
a.extend([4,5,6])
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初始化
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@a = (undef) x 10;
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a = [None] * 10
a = [None for i in range(0, 10)]
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浅拷贝深拷贝
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use Storable 'dclone'
my @a = (1,2,[3,4]);
my $a2 = \@a;
my @a3 = @a;
my @a4 = @{dclone(\@a)};
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import copy
a = [1,2,[3,4]]
a2 = a
a3 = list(a)
a4 = copy.deepcopy(a)
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数组作为函数参数
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each element passed as separate argument; use reference to pass array as single argument
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parameter contains address copy
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遍历
|
for $i (1, 2, 3) { print "$i\n" }
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for i in [1,2,3]:
print(i)
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遍历
|
none; use range iteration from 0 to $#a and use index to look up value in the loop body
|
a = ['do', 're', 'mi', 'fa']
for i, s in enumerate(a):
print('%s at index %d' % (s, i))
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range
|
for $i (1..1_000_000) {
code
}
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range replaces xrange in Python 3:
for i in xrange(1, 1000001):
code
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range数组
|
@a = 1..10;
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a = range(1, 11)
Python 3:
a = list(range(1, 11))
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翻转
|
@a = (1,2,3);
reverse @a;
@a = reverse @a;
|
a = [1,2,3]
a[::-1]
a.reverse()
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|
排序
|
@a = qw(b A a B);
sort @a;
@a = sort @a;
sort { lc($a) cmp lc($b) } @a;
|
a = ['b', 'A', 'a', 'B']
sorted(a)
a.sort()
a.sort(key=str.lower)
|
|
去重复
|
use List::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(lambda x: x * x, [1,2,3])
# or use list comprehension:
[x*x for x in [1,2,3]]
|
|
filter
|
grep { $_ > 1 } (1,2,3)
|
filter(lambda x: x > 1, [1,2,3])
# or use list comprehension:
[x for x in [1,2,3] if x > 1]
|
|
reduce
|
use List::Util 'reduce';
reduce { $x + $y } 0, (1,2,3)
|
# import needed in Python 3 only
from functools import reduce
reduce(lambda x, y: x+y, [1,2,3], 0)
|
|
All/any
|
# cpan -i List::MoreUtils
use List::MoreUtils qw(all any);
all { $_ % 2 == 0 } (1,2,3,4)
any { $_ % 2 == 0 } (1,2,3,4)
|
all(i%2 == 0 for i in [1,2,3,4])
any(i%2 == 0 for i in [1,2,3,4])
|
|
shuffle and sample
|
use List::Util 'shuffle';
@a = (1, 2, 3, 4);
shuffle(@a);
none
|
from random import shuffle, sample
a = [1, 2, 3, 4]
shuffle(a)
sample(a, 2)
|
|
zip
|
# cpan -i List::MoreUtils
use List::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 as undef:
$d{"lorem"};
adds key/value pair:
$d{"lorem"} = "ipsum";
|
d = {}
raises KeyError:
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 $d{1};
|
d = {1: True, 0: False}
del d[1]
|
|
from array of pairs, from even length array
|
@a = (1,"a",2,"b",3,"c");
%d = @a;
|
a = [[1,'a'], [2,'b'], [3,'c']]
d = dict(a)
a = [1,'a',2,'b',3,'c']
d = dict(zip(a[::2], a[1::2]))
|
|
merge
|
%d1 = (a=>1, b=>2);
%d2 = (b=>3, c=>4);
%d1 = (%d1, %d2);
|
d1 = {'a':1, 'b':2}
d2 = {'b':3, 'c':4}
d1.update(d2)
# {'a': 1, 'c': 4, 'b': 3}
|
|
invert
|
%to_num = (t=>1, f=>0);
%to_let = reverse %to_num;
|
to_num = {'t':1, 'f':0}
# dict comprehensions added in 2.7:
to_let = {v:k for k, v
in to_num.items()}
|
|
iteration
|
while ( ($k, $v) = each %d ) {
code
}
|
for k, v in d.iteritems():
code
Python 3:
for k, v in d.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
|
from collections import defaultdict
counts = defaultdict(lambda: 0)
counts['foo'] += 1
class Factorial(dict):
def __missing__(self, k):
if k > 1:
return k * self[k-1]
else:
return 1
factorial = Factorial()
|
|
函数
|
|
函数申明
|
sub add { $_[0] + $_[1] }
sub add {
my ($a, $b) = @_;
$a + $b;
}
|
def add(a, b):
return a+b
|
|
函数调用
|
add(1, 2);
parens are optional:
add 1, 2;
|
add(1, 2)
|
|
参数丢失
|
set to undef
|
raises TypeError
|
|
参数默认值
|
sub my_log {
my $x = shift;
my $base = shift // 10;
log($x)/log($base);
}
my_log(42);
my_log(42, exp(1));
|
import math
def my_log(x, base=10):
return math.log(x)/math.log(base)
my_log(42)
my_log(42, math.e)
|
|
变长参数
|
sub foo {
if ( @_ >= 1 ) {
print "first: $_[0]\n";
}
if ( @_ >= 2 ) {
print "last: $_[-1]\n";
}
}
|
def foo(*a):
if len(a) >= 1:
print('first: ' + str(a[0]))
if len(a) >= 2:
print('last: ' + str(a[-1]))
|
|
命名参数
|
none
|
def fequal(x, y, **opts):
eps = opts.get('eps') or 0.01
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
|
sub foo {
$_[0] += 1;
$_[1] .= "ly";
}
my $n = 7;
my $s = "hard";
foo($n, $s);
|
not possible
|
|
pass array or dictionary by reference
|
sub foo {
$_[0][2] = 5;
$_[1]{"f"} = -1;
}
my @a = (1,2,3);
my %d = ("t"=> 1, "f" => 0);
foo(\@a, \%d);
|
def foo(x, y):
x[2] = 5
y['f'] = -1
a = [1,2,3]
d = {'t':1, 'f':0}
foo(a, d)
|
|
return value
|
return arg or last expression evaluated
|
return arg or None
|
|
multiple return values
|
sub first_and_second {
return ($_[0], $_[1]);
}
@a = (1,2,3);
($x, $y) = first_and_second(@a);
|
def first_and_second(a):
return a[0], a[1]
x, y = first_and_second([1,2,3])
|
|
lambda declaration
|
$sqr = sub { $_[0] * $_[0] }
|
body must be an expression:
sqr = lambda x: x * x
|
|
lambda invocation
|
$sqr->(2)
|
sqr(2)
|
|
function reference
|
my $func = \&add;
|
func = add
|
|
function with private state
|
use feature state;
sub counter {
state $i = 0;
++$i;
}
print counter() . "\n";
|
# state not private:
def counter():
counter.i += 1
return counter.i
counter.i = 0
print(counter())
|
|
closure
|
sub make_counter {
my $i = 0;
return sub { ++$i };
}
my $nays = make_counter;
print $nays->() . "\n";
|
# Python 3:
def make_counter():
i = 0
def counter():
nonlocal i
i += 1
return i
return counter
nays = make_counter()
|
|
generator
|
none
|
def make_counter():
i = 0
while True:
i += 1
yield i
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"
}
|
if 0 == n:
print('no hits')
elif 1 == n:
print('one hit')
else:
print(str(n) + ' hits')
|
|
switch
|
use feature '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++ }
|
while i < 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 continue none
|
|
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
|
raises NameError unless a value was assigned to it
|
|
statement modifiers
|
print "positive\n" if $i > 0;
print "nonzero\n" unless $i == 0;
|
none
|
|
raise exception
|
die "bad arg";
|
raise Exception('bad arg')
|
|
catch exception
|
eval { risky };
if ($@) {
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
|
class Bam(Exception):
def __init__(self):
super(Bam, self).__init__('bam!')
|
|
catch exception by type
|
none
|
try:
raise Bam()
except Bam as e:
print(e)
|
|
finally/ensure
|
none
|
acquire_resource()
try:
risky()
finally:
release_resource()
|
|
start thread
|
use threads;
$func = sub { sleep 10 };
$thr = threads->new($func);
|
class sleep10(threading.Thread):
def run(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
|
open my $f, "/etc/hosts"; or
open FILE, "/etc/hosts";
|
f = open('/etc/hosts')
|
|
open file for writing
|
open my $f, ">/tmp/perl_test"; or
open FILE, ">/tmp/perl_test";
|
f = open('/tmp/test', 'w')
|
|
open file for append
|
|
with open('/tmp/test') as f:
f.write('lorem ipsum\n')
|
|
close file
|
close $f; or
close FILE;
|
f.close()
|
|
read line
|
$line = <$f>; or
$line = <FILE>;
|
f.readline()
|
|
iterate over file by line
|
while ($line = <$f>) {
|
for line in f:
|
|
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
|
use IO::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
|
use File::Copy;
copy("/tmp/foo", "/tmp/bar");
unlink "/tmp/foo";
move("/tmp/bar", "/tmp/foo");
unlink();
|
import shutil
shutil.copy('/tmp/foo', '/tmp/bar')
os.remove('/tmp/foo')
shutil.move('/tmp/bar', '/tmp/foo')
os.remove()
|
|
set file permissions
|
chmod 0755, "/tmp/foo";
|
os.chmod('/tmp/foo', 0755)
|
|
temporary file
|
use File::Temp;
$f = File::Temp->new();
print $f "lorem ipsum\n";
close $f;
print "tmp file: ";
print $f->filename . "\n";
|
import tempfile
f = tempfile.NamedTemporaryFile(
prefix='foo')
f.write('lorem ipsum\n')
f.close()
print("tmp file: %s" % f.name)
|
|
in memory file
|
my ($f, $s);
open($f, ">", \$s);
print $f "lorem ipsum\n";
$s;
|
from StringIO import StringIO
f = StringIO()
f.write('lorem ipsum\n')
s = f.getvalue()
Python 3 moved StringIO to the io module
|
|
目录操作
|
|
build pathname
|
use File::Spec;
File::Spec->catfile("/etc", "hosts")
|
os.path.join('/etc', 'hosts')
|
|
dirname and basename
|
use File::Basename;
print dirname("/etc/hosts");
print basename("/etc/hosts");
|
os.path.dirname('/etc/hosts')
os.path.basename('/etc/hosts')
|
|
absolute pathname
|
use Cwd;
Cwd::abs_path("..")
|
os.path.abspath('..')
|
|
iterate over directory by file
|
use File::Basename;
while ( </etc/*> ) {
print basename($_) . "\n";
}
|
for filename in os.listdir('/etc'):
print(filename)
|
|
make directory
|
use File::Path 'make_path';
make_path "/tmp/foo/bar";
|
dirname = '/tmp/foo/bar'
if not os.path.isdir(dirname):
os.makedirs(dirname)
|
|
recursive copy
|
# cpan -i File::Copy::Recursive
use File::Copy::Recursive 'dircopy';
dircopy "/tmp/foodir",
"/tmp/bardir";
|
import shutil
shutil.copytree('/tmp/foodir',
'/tmp/bardir')
|
|
remove empty directory
|
rmdir "/tmp/foodir";
|
os.rmdir('/tmp/foodir')
|
|
remove directory and contents
|
use File::Path 'remove_tree';
remove_tree "/tmp/foodir";
|
import shutil
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
$0
|
len(sys.argv)-1
sys.argv[1] sys.argv[2] etc
sys.argv[0]
|
|
getopt
|
use Getopt::Long;
my ($src, $help);
sub usage {
print "usage: $0 --f SRC\n";
exit -1;
}
GetOptions("file=s" => \$src,
"help" => \$help);
usage if $help;
|
import argparse
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
|
exit 0;
|
sys.exit(0)
|
|
set signal handller
|
$SIG{INT} = sub {
die "exiting…\n";
};
|
import signal
def handler(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";
|
if os.system('ls -l /tmp'):
raise Exception('ls failed')
|
|
escaped external command
|
$path = <>;
chomp($path);
system("ls", "-l", $path) == 0 or
die "ls failed";
|
import subprocess
cmd = ['ls', '-l', '/tmp']
if subprocess.call(cmd):
raise Exception('ls failed')
|
|
backticks
|
my $files = `ls -l /tmp`; or
my $files = qx(ls);
|
import subprocess
cmd = ['ls', '-l', '/tmp']
files = subprocess.check_output(cmd)
|
|
__________________________________________
|
