Python os.path.sameopenfile() Method

Python os.path.sameopenfile() method is used to check if two file descriptors refer to the same file.

In Unix-like systems, a file descriptor is an integer uniquely identifying an open file for the process. The operating system uses them to keep track of open files.

The standard file descriptors are 0 (standard input), 1 (standard output), and 2 (standard error).

The file descriptors can refer to different fileno() but point to the same open file. This method checks if the inode number and device number are the same.

It works for files opened in text or binary mode.

The file descriptors must be valid – it will raise an OSError if any are invalid.

It can be used to check if a file is already open before opening it again to avoid duplicates.

It helps check if two threads are operating on the same open file object.

It does not compare regular path strings; it only opens file descriptors.

Syntax

os.path.sameopenfile(fd1, fd2)

Parameters

Name Description
fd1 It is a file descriptor.
fd2 It is a file descriptor.

Return value

It returns True if both file descriptors fd1 and fd2 refer to the same file; False otherwise.

Example 1: Checking two file descriptors pointing to the same file

Visual Representation of Python os.path.sameopenfile() Method

import os

path = "/Users/krunallathiya/Desktop/Code/pythonenv/env/file.txt"

fd1 = os.open(path, os.O_RDONLY)

file_desc = open(path, mode='r')

fd2 = file_desc.fileno()

same_file = os.path.sameopenfile(fd1, fd2)

print(same_file)

Output

True

In this example, the same file is opened twice, resulting in two different descriptors. Since both descriptors refer to the same “file.txt” file, it returns True.

Example 2: Checking two file descriptors pointing to the different file

Checking two file descriptors pointing to the different file

import os

path1 = "/Users/krunallathiya/Desktop/Code/pythonenv/env/file.txt"
path2 = "/Users/krunallathiya/Desktop/Code/pythonenv/env/new.txt"

fd1 = os.open(path1, os.O_RDONLY)

file_desc = open(path2, mode='r')

fd2 = file_desc.fileno()

same_file = os.path.sameopenfile(fd1, fd2)

print(same_file)

Output

False

Since both file descriptors differ, we got the False in the output.

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