Python - Test read permissions

Question

Is there a function that returns, in Python, True if I have read permissions for the python file?

Answer 1

You can use the function access(path, mode) module os.

Take an example:

if os.access("foo.txt", os.R_OK):
    with open("foo.txt") as fp:
        # Fazer algo aqui

The first parameter of the function is the file path to be checked and the second parameter is used to specify the mode to be used.

Manners are:

• os.F_OK: To test the existence of path.
• os.R_OK: Used to check whether path can be read.
• os.W_OK: To verify the writing ability of path.
• os.X_OK: To check whether path can be executed.

Alternatively you can use the function stat also belonging to the module os together with the auxiliary module stat which allows working with a larger set of options.

import os
import stat

filename = "foo.txt"
if os.path.exists(filename):
    st = os.stat(filename)
    print (bool(st.st_mode & stat.S_IRUSR))
else:
    print ("{0} nao foi encontrado.".format(filename))

We use an operation bitwise & to assess whether each bit output is 1 if the bit corresponding to the attribute ST_MODE and S_IRUSR is 1, if it’s not 0 and use the result of the operation in function bool who will show True or False.

• ST_MODE: It is used to obtain the bits file protection.
• S_IRUSR: Owner has reading permission.