如何在python中调用linux命令

工作中经常会用python去调用shell的命令，今天看到了在stack overflow上的一个答案，用到了subprocess的模块，感觉很简单实用，所以分享一下。

Look at the subprocess module in the stdlib:

from subprocess import call
call(["ls", "-l"])

The advantage of subprocess vs system is that it is more flexible (you can get the stdout, stderr, the "real" status code, better error handling, etc...). I think os.system is deprecated, too, or will be:

http://docs.python.org/library/subprocess.html#replacing-older-functions-with-the-subprocess-module

For quick/dirty/one time scripts, os.system is enough, though.

另个更加详细的解释：

Here's a summary of the ways to call external programs and the advantages and disadvantages of each:

1. os.system("some_command with args") passes the command and arguments to your system's shell. This is nice because you can actually run multiple commands at once in this manner and set up pipes and input/output redirection. For example,
   os.system("some_command < input_file | another_command > output_file")
   However, while this is convenient, you have to manually handle the escaping of shell characters such as spaces, etc. On the other hand, this also lets you run commands which are simply shell commands and not actually external programs.
   http://docs.python.org/lib/os-process.html

2. stream = os.popen("some_command with args") will do the same thing as os.system except that it gives you a file-like object that you can use to access standard input/output for that process. There are 3 other variants of popen that all handle the i/o slightly differently. If you pass everything as a string, then your command is passed to the shell; if you pass them as a list then you don't need to worry about escaping anything.
   http://docs.python.org/lib/os-newstreams.html

3. The Popen class of the subprocess module. This is intended as a replacement for os.popen but has the downside of being slightly more complicated by virtue of being so comprehensive. For example, you'd say
   print Popen("echo Hello World", stdout=PIPE, shell=True).stdout.read()
   instead of
   print os.popen("echo Hello World").read()
   but it is nice to have all of the options there in one unified class instead of 4 different popen functions.
   http://docs.python.org/lib/node528.html

4. The call function from the subprocess module. This is basically just like the Popen class and takes all of the same arguments, but it simply wait until the command completes and gives you the return code. For example:
   return_code = call("echo Hello World", shell=True)
   http://docs.python.org/lib/node529.html

5. The os module also has all of the fork/exec/spawn functions that you'd have in a C program, but I don't recommend using them directly.

The subprocess module should probably be what you use.