Python 3 – os.fdatasync() Method
Python has an extensive built-in library known as OS or Operating System module that allows python users to interact with the system at the very low level. The Operating System module has several methods to perform different low-level operations like file creation, changes, and managing directories. One of such functions is os.fdatasync().
The os.fdatasync() method is used to flush write-behind data blocks from the internal buffer caches. It synchronizes the file modification and writes the data in the buffer cache to the storage device, but skips writing inode and directory update times. This method is available only on Unix-like systems, including macOS X and Linux.
Syntax
The basic syntax of using the os.fdatasync() method is given as:
os.fdatasync(file_descriptor)
The method takes a single argument, which is the file descriptor that returns a file object that’s been used to read, write, and modify files. The os.fsync() method also takes the same argument.
Parameters
The os.fdatasync() method takes a single parameter:
- file_descriptor (required): A directory descriptor that returns the file object and specifies the open file to flush. The method synchronizes the buffer with the file descriptor.
Return Value
The os.fdatasync() method does not return any value.
Usage
The os.fdatasync() method is used to synchronize the memory buffer with the group data block. The data block contains the data written to the file from the buffer. This method allows the programmer to flush the applied changes to the file from the buffer. It doesn’t update the access and the modification times of the inode and directory.
Let’s suppose that we have a file, “data.text,” that we opened in write and read mode, so we can read or write content from the file. The following code snippet shows how to use fdatasync() to save the changes in the files:
import os
file_descriptor = os.open("data.txt, os.O_RDWR )
# do the writing or reading operations
os.fdatasync(file_descriptor)
os.close(file_descriptor)
In the code above, we saw the os.open method being used to open a file in read and write mode. “os.O_RDWR” opens the file in read-write mode. Further, we perform the read and write operations on the file. Once done, we use “os.fdatasync()” to write the buffer data to the file’s data block.
Example
Let’s take a practical example to demonstrate how to use the os.fdatasync() method. In this example, we read from the file, “sample.txt”, and then write the new data we have read to the same file using the os.fdatasync() method.
import os
file_descriptor = os.open("sample.txt", os.O_RDWR )
# read from file
read_content = os.read(file_descriptor, os.path.getsize("sample.txt"))
# write to file
os.write(file_descriptor, read_content)
#flush write behind data from the buffer
os.fdatasync(file_descriptor)
#close the file descriptor
os.close(file_descriptor)
In the code above, we opened the “sample.txt” file in read and write mode. We then read the file contents and save the contents in a variable “read_content”. Later, we wrote the content of the variable “read_content” to the same file using “os.write()” method.
Finally, we flush written behind data from the buffer using “fdatasync” and close the file descriptor using “os.close()”.
Conclusion
In conclusion, the os.fdatasync() method flushes data blocks from the internal buffer cache to synchronization file modification. This method only updates data blocks but does not update access and modification times of inodes and directories. We hope you now have a good understanding of the os.fdatasync() method’s syntax, parameters, return value, and usage in python. Keep practicing to improve your Python skills.