Reading from files with file descriptors
In the previous recipe, we learned how to write to files using file descriptors. In this recipe, we will learn how to read from files using file descriptors. We will therefore write a small program that is similar to
cat. It takes one argument—a filename—and prints its content to standard output.
Knowing how to read—and use—file descriptors enables you to read not only files but all sorts of data that comes through a file descriptor. File descriptors are a universal way to read and write data in Unix and Linux.
The only things you'll need for this recipe are listed under the Technical requirements section of this chapter.
How to do it…
Reading a file using a file descriptor is similar to writing to one. Instead of using the
write() system call, we will instead use the
read() system call. Before we can read the content, we must figure out the size of the file first. We can use...