In [1]: s1 = 'abc'

In [2]: help(s1.startswith)

Help on built-in function startswith:

startswith(...)

S.startswith(prefix[, start[, end]]) -> bool

Return True if S starts with the specified prefix, False otherwise.

With optional start, test S beginning at that position.

With optional end, stop comparing S at that position.

prefix can also be a tuple of strings to try.

(END)

cat /proc/meminfo

#!/usr/bin/python

with open('/proc/meminfo') as fd:

for line in fd:

if line.startswith('MemTotal:'):

total = line.split()[1]

continue

if line.startswith('MemFree:'):

free = line.split()[1]

break

print "%.2f" % (int(free)/1024.0)+'M'

10进制转换成16进制：

In [9]: hex(10)

Out[9]: '0xa'

16进制转换成10进制：

In [8]: int('0xa',16)

Out[8]: 10

In [7]: int('aa',16)

Out[7]: 170

In [10]: int('10')

Out[10]: 10

10进制转换成字符串：

In [11]: str(10)

Out[11]: '10'

#!/usr/bin/python

plus_one = int(last_two,16)+1

if plus_one in range(10):

new_last_two = hex(plus_one)[2:]

new_last_two = '0' + new_last_two

else:

new_last_two = hex(plus_one)[2:]

if len(new_last_two) == 1:

new_last_two = '0' +new_last_two

new_mac = prefix_mac + ':' + new_last_two

print new_mac.upper()

Help on built-in function join:

join(...)

S.join(iterable) -> string

Return a string which is the concatenation of the strings in the

iterable.  The separator between elements is S.

(END)

In [36]: a = list('aaa')

In [37]: type(a)

Out[37]: list

In [38]: a

Out[38]: ['a', 'a', 'a']

In [38]: a

Out[38]: ['a', 'a', 'a']

In [39]:l = a

In [18]: l

Out[18]: ['a', 'a', 'a']

In [19]: ''.join(l)

Out[19]: 'aaa'

In [20]: ','.join(l)

Out[20]: 'a,a,a'

In [21]: '.'.join(l)

Out[21]: 'a.a.a'

In [22]: a= 'a'

In [23]: help(a.join)

In [24]: s

Out[24]: ['a', 'a', 'a']

In [26]: tuple(s)

Out[26]: ('a', 'a', 'a')

In [54]: type(a)

Out[54]: tuple

In [55]: a = str(a)

In [56]: a

Out[56]: "('a', 'b', 'c', 111)"

In [57]: type(a)

Out[57]: str

In [28]: dic = {'a':1,'b':2}

In [29]: dic

Out[29]: {'a': 1, 'b': 2}

In [30]: dic.items()

Out[30]: [('a', 1), ('b', 2)]

In [31]: l1 = dic.items()

In [32]: l1

Out[32]: [('a', 1), ('b', 2)]

In [33]: type(l1)

Out[33]: list

In [34]: dict(l1)

Out[34]: {'a': 1, 'b': 2}