Pondering PATH

Thus far, you have invoked commands in several ways:

• Through an absolute path (e.g., /challenge/run).
• Through a relative path (e.g., ./run).
• Through a bare command name (e.g., ls).

The first two cases, the absolute and the relative path case, are straightforward: the run file lives in the /challenge directory, and both cases refer to it (provided, of course, that the relative path is invoked with a current working directory of /challenge). But what about the last one? Where is the ls program located? How does the shell know to search for it there?

In this module, we will pull back the veil and answer this question! Stay with us.