Run it by typing its name.
You run the installed program like any command--type its name into a Terminal, optionally add whatever arguments you wish to pass to it, and press Enter.
Check for it with
Another way to check if it will run is by running
which program where
program is the name of the program.
That is to say that
program is what you'd type to run the program.
Verify its name in the documentation.
If you're not sure of its name, check the documentation accompanying the source code (for example, check the
README file in the source code directory.
Did you really install it, or just build it?
Also make sure you remembered to install it. After running
make to compile the source code (and optionally
make check or
make test to test it--usually but not always supported), run
sudo make install to install it).
Try a fresh login, and make sure it's in your PATH.
If the program is installed but
which doesn't show it, try a new login. If it still won't run, make sure
/usr/local/bin is in your
PATH environment variable:
If it's not, add it: How to add a directory to my path?
Manually make sure it exists.
If ensuring it's in your
PATH doesn't fix the problem, make sure the program is actually there.
Check its executable bit.
If it's there but won't run, then as Chan-Ho Suh suggested in a comment, check that the file is marked executable.
You can see this in Nautilus by right-clicking the file and clicking Properties, then clicking the Permissions tab. You can see this in the terminal by running
ls -l and seeing if the
x bit appears. This wiki page explains how to interpret the permissions (see also this article).
If it's not executable, you can make it executable by running
sudo chmod +x program (in the
/usr/local/bin directory where it resides).
Or, if you wish to use Nautilus, you can run Nautilus (Alt+F2, run
gksu nautilus), and in the root Nautilus window, its Permissions tab will let you make changes.
root Nautilus window will let you do just about anything, you can break your Ubuntu system or lose data if you're not careful. Remember that any file opened or program run from a
root Nautilus window gives you an application running as
root. So you should close the
root Nautilus window as soon as you're done with it.
Provide more information to get further help.
If none of this works, we need more information. You can edit your question to provide details about exactly what happened when you did all this stuff. (If you're not the author, you can post your own, new question.)