Python os.lseek() Method

Description

Python method lseek() sets the current position of file descriptor fd to the given position pos, modified by how.

Syntax

Following is the syntax for lseek() method −

os.lseek(fd, pos, how)

Parameters

• fd − This is the file descriptor, which needs to be processed.

• pos − This is the position in the file with respect to given parameter how. You give os.SEEK_SET or 0 to set the position relative to the beginning of the file, os.SEEK_CUR or 1 to set it relative to the current position; os.SEEK_END or 2 to set it relative to the end of the file.

• how − This is the reference point with-in the file. os.SEEK_SET or 0 means beginning of the file, os.SEEK_CUR or 1 means the current position and os.SEEK_END or 2 means end of the file.

Return Value

This method does not return any value.

Example

The following example shows the usage of lseek() method.

#!/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")

# Now you can use fsync() method.
# Infact here you would not be able to see its effect.
os.fsync(fd)

# Now read this file from the beginning
os.lseek(fd, 0, 0)
str = os.read(fd, 100)
print "Read String is : ", str

# Close opened file
os.close( fd )

print "Closed the file successfully!!"

When we run above program, it produces following result −

Read String is :  This is test
Closed the file successfully!!