Absolute Path and Relative Path issue in python

Question

How to remove path related problems in python?

For e.g. I have a module test.py inside a directory TEST

**test.py**
import os
file_path = os.getcwd() + '/../abc.txt'

f = open(file_path)
lines = f.readlines()
f.close

print lines

Now, when I execute the above program outside TEST directory, it gives me error:-

Traceback (most recent call last):
  File "TEST/test.py", line 4, in ?
    f = open(file_path)
IOError: [Errno 2] No such file or directory: 'abc.txt'

how to resolve this kind of problem. Basically this is just a small example that I have given up.

I am dealing with a huge problem of this kind.

I am using existing packages, which needs to be run only from that directory where it exists, how to resolve such kind of problems, so that I can run the program from anywhere I want.

Or able to deal with the above example either running inside TEST directory or outside TEST directory.

Any help.?

Emil Vikström · Accepted Answer · 2012-06-03 10:31:16Z

3

I think the easiest thing is to change the current working directory to the one of the script file:

import os
os.chdir(os.path.dirname(__file__))

This may cause problems, however, if the script is also working with files in the original working directory.

answered Jun 3, 2012 at 10:31

Emil Vikström

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4 Comments

geek Over a year ago

how to use this utility.. It is giving me error. >>> import os >>> os.path.dirname(file) Traceback (most recent call last): File "<stdin>", line 1, in ? NameError: name 'file' is not defined

marshall.ward Over a year ago

Before this degenerates into comedy: The markup is converting two underscores as bold font. Use __file__.

Emil Vikström Over a year ago

__file__ is not defined in in the interpreter. You should use it inside a script file.

geek Over a year ago

Any other solution?? changing the directory might not be useful. I am using unittest module, to run few tests (regression suite) and inside each test, I am using few txt files, which is lying inside a directory in side regression_framework_directory, the path of which can be known through test case only. Now If i run the test case from outside, somewhere else, the txt files are not recognized. Any other solution please.?

Epcylon · Accepted Answer · 2012-06-03 13:32:41Z

Your code is looking at the current working directory, and uses that as a basis for finding the files it needs. This is almost never a good idea, as you are now finding out.

The solution mentioned in the answer by Emil Vikström is a quickfix solution, but a more correct solution would be to not use current working directory as a startingpoint.

As mentioned in the other answer, __file__ isn't available in the interpreter, but it's an excellent solution for your code.

Rewrite your second line to something like this:

file_path = os.path.join(os.path.dirname(__file__), "..", "abc.txt")

This will take the directory the current file is in, join it first with .. and then with abc.txt, to create the path you want.

You should fix similar usage of os.getcwd() elsewhere in your code in the same way.

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