<p>I've got a utility that outputs a list of files required by a game.  How can I run that utility within a C program and grab its output so I can act on it within the same program?</p>
<p>UPDATE: Good call on the lack of information.  The utility spits out a series of strings, and this is supposed to be portable across Mac/Windows/Linux.  Please note, I'm looking for a programmatic way to execute the utility and retain its output (which goes to stdout).</p>

For simple problems in Unix-ish environments try
```
popen()
```
.
From the man page:
The popen() function opens a process by creating a pipe, forking and invoking the shell.
If you use the read mode this is exactly what you asked for. I don't know if it is implemented in Windows.
For more complicated problems you want to look up inter-process communication.