函数调用中的python变量

Question

i'm trying to create a directory/folder in linux using python. I will get date time and make a folder.

In [65]: d = datetime.datetime.now()

In [66]: a = 'date :' + str(d)

In [67]: a
Out[67]: 'date :2011-02-01 13:05:58.642704'

In [68]: os.system('mkdir a')

How should i pass the variable a in the system command??

Answer 1

使用字符串格式将var a添加到字符串：

os.system('mkdir %s' % a)

Answer 2

使用python自己的目录制作方式：

os.mkdir(a)

Answer 3

Are you sure you want to name your directory 'date :2011-02-01 13:05:58.642704' with all those colons and spaces? There is a simple way to format the date in a different form, that will make the string manipulation easier.

For example:

d = datetime.datetime.now()

a = d.strftime('date_%Y%m%d_%H%M%S_%f')
os.mkdir(a)

which will create a directory named date_20110201_130558_642704 (more about the formatting options here ). Your life will be easier if you manipulate this directory in the shell (double-clicking on its name in an ls output, etc.)

Answer 4

You should not use os.system . Use subprocess if you have to call an external program.

That said, there is no reason to call mkdir . Use the stdlib function os.mkdir , that does what you want. Using the stdlib wherever possible is recommended. Not only will your code be portable, it will be easier to maintain and read also.

If you insist on calling an external process:

>>> import subprocess
>>> subprocess.call(['mkdir', 'foo_bar'])