12.3. Starting Applications

I installed an application 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 does 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/my-executable).

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 type the full pathnames in order to start an application is because the executable was not placed in a directory where your user shell environment knew it could be found (such as /usr/local/bin).

You can customize your settings so that you are not required to use the type the full path to the application each time. To do this, you must edit your PATH environment variable.

12.3.1. Editing Your PATH

If you frequently start programs that are not located in a directory that your user shell has been configured to search, you must edit your user shell configuration file to add the directory containing the executable you wish to run. You can do this by adding the directory to your PATH environment variable.


These instructions are intended only for user accounts. Avoid modifying files such as the root user's .bash_profile, because of the potential security risks.

Start a text editor, such as gedit or vi, at a shell prompt. You can open the file called .bash_profile by typing the following:

gedit .bash_profile

Look for a PATH statement, similar to the one shown below.


To the end of this statement, add $HOME/seti as shown below:


Save the file and exit the text editor.

You can then make the changes to .bash_profile take effect immediately by typing the following command:

source .bash_profile

By adding paths to your .bash_profile, you can place utilities and programs in your path and be able to execute them without having to type ./ in front of the command.


For more information about using and configuring your shell prompt refer to Chapter 3 Shell Prompt Basics.