PATH environment variable.
Normally you don't want to override the system settings;
instead, append to the current PATH
[amit@onyx]: export PATH="$PATH:/extra/dir"
with new entries delimited with a colon.
The setting for the PATH variable goes in .bash_profile or .bashrc file.
A common situation is that the current directory is not in your path. So you have to specify the path using the dot notation:
./myprog
While that works, we can add the current directory to the PATH so that we do not have to prefix each time with the ./ prefix. Here is the setting.
export PATH=$PATH:.
Add this line at the end of your .bashrc file in your home directory.