How to open a file given in input in python?

Question

I'm working on a project and for this I need to open a file. So for this I wanted to use open("my_file", "r") but the problem is that the name of the file is dynamic, it could be toto.txt or jziop.txt I no matter how the user will call it. I know in C I would just use open with the av[1] but is it possible in python ? I'm new in it so I'm learning.

Thanks

Use sys.argv[1]. Command line arguments can be accessed from sts.argv[] array. — fiveobjects
– fiveobjects, Commented Aug 4, 2019 at 14:06
It's not always the same name, the user can input a .txt file with a total random name. — hissroth
– hissroth, Commented Aug 4, 2019 at 14:06
you already have the answer from comments fname = sys.argv[1] - just use it — RomanPerekhrest
– RomanPerekhrest, Commented Aug 4, 2019 at 14:08

Martin Gergov · Accepted Answer · 2019-08-04 14:09:55Z

1

import sys
f = open(sys.argv[1], "r")
# do stuff
f.close()

This will read the first argument and place it as the filename.

answered Aug 4, 2019 at 14:09

Martin Gergov

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3 Comments

U13-Forward Over a year ago

Personally i wouldn't still a code from the comments.

RomanPerekhrest Over a year ago

Let's show some dignity and not post a ready answers from comments

snow_abstraction Over a year ago

@u Isn't good that some actually writes some answer that can be voted up or down? The answer could be improved with an explanation or reference but at least it is complete.

David Callanan · Accepted Answer · 2019-08-04 16:29:43Z

1

If you import sys (a built-in module), you will have access to the sys.argv variable, a list holding all arguments passed into your program.

The first argument sys.argv[0] is the path to your program, so you actually want the second argument sys.argv[1]

python  my_script.py  my_file.txt
        ^~~~~~~~~~~~  ^~~~~~~~~~~
        sys.argv[0]   sys.argv[1]

Final code snippet:

import sys

assert len(sys.argv) >= 2

with open(sys.argv[1]) as f:
  data = f.read()

edited Aug 4, 2019 at 16:29

answered Aug 4, 2019 at 14:23

David Callanan

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