Difference Between os.open and os.fdopen in Python

The open() function is a built-in Python function that helps you work with files, however, the os module offers low-level file handling functions that give more control over how files are opened and managed, two of such function from the os module are os.open() and os.fdopen(). 

The key difference between both os.open() and os.fdopen() functions is that os.open() is used to open a file and extract its file descriptor, while os.fdopen() is used to wrap an existing file descriptor and create a file object.

What is os.open() Function?

The os.open() function in the os module opens the specified file and returns a descriptor, which is defined as an integer value that identifies the open file from a chunk of open files kept by the kernel for each process. 

Syntax

The syntax for the os.open() function is given below -

 os.open(path, flags, mode = 0o777, *, dir_fd=None);

The parameters are -

• path: Path to the file
• flags: File access modes (os.O_RDONLY, os.O_WRONLY, os.O_RDWR)

What is os.fdopen()?

The os.fdopen() function converts a file descriptor( similar to the one returned by the os.open() function) into a file object, which allows you to use operations like .read(), .write(), and .close().

Syntax

The syntax for the os.fdopen() function is given below -

os.fdopen(fd, [, mode[, bufsize]]);

The parameters are -

• fd: File descriptor (integer)
• mode: File mode like 'r', 'w', 'rb', and etc.
• bufsize: This optional argument specifies the file's desired buffer size: 0 means unbuffered, 1 means line buffered, and any other positive value means use a buffer of (approximately) that size.

Differences Between os.open() and os.fdopen()

Following is a table that consists of the differences between os.open() and os.fdopen() -