If you are trying to find a program, login to the shell.
Typing “whereis program”, where “program” is the application you are looking for, will show you one or more possibilites for what you are looking for. If you have more than one copy of a program, for example in /usr/bin/ and another in /usr/local/bin/, typing “which program” will show you the application that will be called first by the shell. If you can’t find it at all, typing “locate program” will show you every file that matches “program”
Some of the most common programs:
Default locations for most commonly used configuration files and important directories: