Iterating through directories with Python

I need to iterate through the subdirectories of a given directory and search for files. If I get a file I have to open it and change the content and replace it with my own lines.

I tried this:

    import os

    rootdir ='C:/Users/sid/Desktop/test'

    for subdir, dirs, files in os.walk(rootdir):
        for file in files:
            f=open(file,'r')
            lines=f.readlines()
            f.close()
            f=open(file,'w')
            for line in lines:
                newline = "No you are not"
                f.write(newline)
            f.close()

but I am getting an error. What am I doing wrong?

The actual walk through the directories works as you have coded it. If you replace the contents of the inner loop with a simple print statement you can see that each file is found:

    import os
    rootdir = 'C:/Users/sid/Desktop/test'

    for subdir, dirs, files in os.walk(rootdir):
        for file in files:
            print os.path.join(subdir, file)

If you still get errors when running the above, please provide the error message.

From: stackoverflow.com/q/19587118