Writing to files with file descriptors

We have already seen some uses of file descriptors in previous chapters, for example, 0, 1, and 2 (stdin, stdout, and stderr). But in this recipe, we will use file descriptors to write text to files from a program.

Knowing how to use file descriptors to write to files both gives you a deeper understanding of the system and enables you to do some low-level stuff.

Getting ready

For this recipe, you only need what is listed under the Technical requirements section.

How to do it…

Here we will write a small program that writes text to a file:

1. Write the following code in a file and save it as fd-write.c. The program takes two arguments: a string and a filename. To write to a file using file descriptors, we must first open the file with the open() system call. The open() system call returns a file descriptor, which is an integer. We then use that file descriptor (the integer) with the write() system call. We have already...