Monday, August 10, 2020

Python os.open() Method with example



Hello dear readers! Welcome back to another section of our tutorial on Python. In this tutorial guide, we are going to be studying about the Os open() method.

The Python's os open() method opens file and sets different flags according to flags and possibly it's mode according to mode. Here 0777 is the default mode, and the current unmask value is then first masked out.

Syntax

The following below is the syntax for Python Os open() method -

os.open(file,  flags[,  mode] );


Parameter Details

  • file - The file name to be opened.
  • flags - The constants below are the options for flags. They can be combined using the bitwise OR operator |. Some are not obtainable on all platforms.
    • os.O_RDONLY - it opens for reading only
    • os.O_WRONLY - it opens for writing only
    • os.O_RDWR - open for both reading and writing
    • os.O_NONBLOCK - do not block on open
    • os.O_APPEND - append on each of the write
    • os.O_CREAT - creates file if it does not exist.
    • os.O_TRUNC - truncate size to 0
    • os.O_EXCL - error if both create and file exists
    • os.O_SHLOCK - atomically obtain a shared lock
    • os.O_EXLOCK - atomically obtain an exclusive lock
    • os.O_DIRECT - eliminate or reduce cache effects
    • os.O_FSYNC - synchronous writes
    • os.O_NOFOLLOW - do not follow the symbolic links
  • mode - This works in similar way as it works for chmod() method.

Return Value

It returns the file descriptor for the newly opened file.

Example

The following below is a simple example -

#!/usr/bin/python

import os, sys

# Open a file
fd = os.open( "foo.txt", os.O_RDWR|os.O_CREAT )

# Write one string
os.write(fd, "This is test")

# Close opened file
os.close( fd )

print "Closed the file successfully!!"

Output
When the above code is executed, it will produce the following result -

Closed the file successfully!!


Alright guys! This is where we are rounding up for this tutorial post. In our next tutorial, we are going to be discussing about Python the OS openpty() Method.

Feel free to ask your questions where necessary and i will attend to them as soon as possible. If this tutorial was helpful to you, you can use the share button to share this tutorial.

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Thanks for reading and bye for now.
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