Understanding System Programming: Writting the who command

Scott Cosentino
6 min readDec 23, 2019

When working with operating systems, you will often interact with system resources using system calls. Learning how to interact with system resources is the purpose of the study of system programming. We will take a look at common command line utilities in Linux, learn how they work, and learn how to implement our own versions of them. In doing this, we will gain a good understanding of how operating systems handle resources, and how a program can interact with them.