Python os.read() Method

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The Python os.read() method is used to read a specified number of bytes from a file associated with the given file descriptor. And, returns a byte string containing the bytes read.

If end of file is reached while reading, it will return an empty bytes object.

Syntax

Following is the syntax for Python os.read() method −

os.read(fd, n)

Parameters

The Python os.read() method accepts two parameters that are listed below −

• fd − This is the file descriptor of the file.

• n − This parameter indicates the number of bytes to read from the file.

Return Value

The Python os.read() method returns a string containing the bytes read.

Example

The following example shows the usage of read() method. Here, we first get the size of file and then, read the text from it.

import os, sys

# Open a file
fd = os.open("newFile.txt", os.O_RDWR)

#getting file size
f_size = os.path.getsize("newFile.txt")	

# Reading text
ret = os.read(fd, f_size)
print("Reading text from file: ")
print (ret)

# Close opened file
os.close(fd)
print ("file closed successfully!!")

Let us compile and run the above program, this will print the contents of file "newFile.txt" −

Reading text from file...
b'This is tutorialspoint'
file closed successfully!!

Example

In the below example, we read the first 10 characters from the given file using read() method.

import os, sys

# Open a file
fd = os.open("newFile.txt", os.O_RDWR)

# Reading text
ret = os.read(fd, 10)
print("Reading text from file: ")
print (ret)

# Close opened file
os.close(fd)
print ("file closed successfully!!")

On running the above program, it will print the first 10 characters of file "newFile.txt" −

Reading text from file: 
b'This is tu'
file closed successfully!!