Run shell commands in Python

From: http://stackoverflow.com/questions/89228/how-to-call-external-command-in-python

 

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
   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
   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 thingos.system
   Could t 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
   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. ThePopen
   Class ofsubprocess
   Module. This is intended as a replacementos.popen
   But has the downside of being slightly more complicated by using UE of being so comprehensive. For example, you 'd say
   print Popen("echo Hello World", stdout=PIPE, shell=True).stdout.read()
   
   Instead
   print os.popen("echo Hello World").read()
   
   But it is nice to have all of the options there in one uniied class instead of 4 different popen functions.
   Http://docs.python.org/lib/node528.html

4. Thecall
   Function fromsubprocess
   Module. This is basically just likePopen
   Class and takes all of the same arguments, but it simply wait until
   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.

I have also used the output after the commands. getoutput ("ls") command is executed.