how to invoke the shell command and then get the result in python

[Fredrik Lundh]

Bin Chen wrote:
> I want to do following: get a user input regex, then pass this as a
> parameter to grep, and then get the result from grep.
> 
> Any code snip to implement the similar function? I am a python newbie.

	import os
	for line in os.popen("grep pattern *.txt"):
            print line,

also see os.system and subprocess.

note that if you want to write portable code, you can implement your own
"grep" using the "re" module:

        import re
        p = re.compile(pattern)
        for index, line in enumerate(open(filename)):
            if p.match(line):
                print index, line,

</F>