Python 3 – os.write() Method
In Python, os.write()
is a method that writes the specified byte string to the file descriptor. This method is only available on platforms that support the “Unix” system call and is commonly used for low-level file operations.
The syntax for os.write()
is as follows:
os.write(fd, data)
Here, fd
is the file descriptor where the data will be written and data
is the byte string that will be written.
If the write operation is successful, the number of bytes written will be returned. Otherwise, an exception will be raised.
Let’s now look at some examples to better understand how os.write()
works.
Example 1: Writing to a File
import os
# Open file for writing
file_desc = os.open("example.txt", os.O_WRONLY)
# Write byte string to file descriptor
data = b"Hello, World!\n"
bytes_written = os.write(file_desc, data)
# Close file descriptor
os.close(file_desc)
print("Number of bytes written:", bytes_written)
In this example, we open a file named “example.txt” in write-only mode (os.O_WRONLY
) and obtain a file descriptor. We then write the byte string “Hello, World!\n” to the file descriptor using os.write()
. Finally, we close the file descriptor and print out the number of bytes written.
Example 2: Writing to Standard Output
import os
# Write byte string to standard output (file descriptor 1)
data = b"Hello, World!\n"
os.write(1, data)
In this example, we directly write the byte string “Hello, World!\n” to the standard output (file descriptor 1) using os.write()
.
Example 3: Handling Exceptions
import os
try:
# Write byte string to non-existent file descriptor
data = b"Hello, World!\n"
bytes_written = os.write(42, data)
print("Number of bytes written:", bytes_written)
except OSError as e:
print("Error:", e)
In this example, we intentionally try to write to a non-existent file descriptor (42
) and catch the resulting OSError
. Upon an unsuccessful write operation, os.write()
raises an exception.
Conclusion
In this article, we explored the os.write()
method in Python and demonstrated how to use it for low-level file operations. We discussed the syntax, the return value, and provided several examples to help you better understand the usage of this method. Remember that os.write()
is only available on platforms that support the “Unix” system call, so make sure to check the documentation to see if it is available on your platform.