Question: I installed an application that I downloaded from the Internet, and everything seemed to go fine, but I still get "command not found" when I type its name. I think I have the right name, so why will it not start?
If you are trying to start an application from the shell prompt and it is not working, try typing out the full directory path before the name of the application's executable (such as /usr/local/bin/myexecutable).
For example, imagine that you have downloaded the setiathome client application and want to try it out. You follow the directions for installing the software, which creates a subdirectory in your home directory called seti/. Now, start the application using the full path to the executable file as shown below:
The reason you may need to use the full pathnames in order to start an application is because the executable wasn't placed in a directory where your user shell environment knew it could be found (such as /usr/local/bin) — that is, the application’s starting command is not in your PATH. You can customize your settings so that you won't be required to type the full path to the application each time. To do this, you will have to edit your PATH environment variable, as discussed in the next section.