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os.ftruncate() - os


The method ftruncate() truncates the file corresponding to file descriptor fd, so that it is at most length bytes in size.

  • fd -- This is the file descriptor, which needs to be truncated.

  • length -- This is the length of the file where file needs to be truncated.


os.ftruncate(fd, length)



import os, sys

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

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

# Now you can use ftruncate() method.
os.ftruncate(fd, 10)

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

# Close opened file
os.close( fd )

print "Closed the file successfully!!"

Output / Return Value

When we run above program, it produces following result:

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


Alternatives / See Also