How can I open multiple files using "with open" in Python?
As of Python 2.7 (or 3.1 respectively) you can write
with open('a', 'w') as a, open('b', 'w') as b: do_something()
In earlier versions of Python, you can sometimes use
contextlib.nested() to nest context managers. This won't work as expected for opening multiples files, though -- see the linked documentation for details.
In the rare case that you want to open a variable number of files all at the same time, you can use
contextlib.ExitStack, starting from Python version 3.3:
with ExitStack() as stack: files = [stack.enter_context(open(fname)) for fname in filenames] # Do something with "files"
Most of the time you have a variable set of files, you likely want to open them one after the other, though.
For opening many files at once or for long file paths, it may be useful to break things up over multiple lines. From the Python Style Guide as suggested by @Sven Marnach in comments to another answer:
with open('/path/to/InFile.ext', 'r') as file_1, \ open('/path/to/OutFile.ext', 'w') as file_2: file_2.write(file_1.read())