Change text/code/numbers in a file using Python

[sudo san]

Hi, I am using python 3.2.3 and also a beginner in python programming.

I would like to know how to go about changing words (or a string of words/numbers) in a file to something else.
I can do this in bash
For example:

sed -i 's/text_in_file/new_text/g' 'path_to_file'

I know that there is some way to do this but I don't want to use os.system as a substitute.

Any ideas?

Thanks in advance.

[ofnuts]

read the file line by line (see open() built-in, and then "for line in file")
for simple editing, use the replace() method on strings, for more complex things, see the "re" module for regexps.
write output to another file.
optional: when done and if everything went OK, erase the original file and rename output file to original file name

[sudo san]

Ok, thanks. I will try later today.

[sudo san]

Sorry, but can you please explain a little further please as I cannot find anything in the python documentation about replace().

[Bodsda]

Sorry, but can you please explain a little further please as I cannot find anything in the python documentation about replace().

It's a string method
http://docs.python.org/2/library/stdtypes.html#string-methods



line = "This is foo"
line.replace("foo", "bar")