A typical value for the PATH variable might be:
This is a path list of colon separated pathnames to the directories that contain the executable binary files for each command.
The shell will first look for the command that has been entered in the directory /bin. If it is not found there it will then look in the directory /usr/bin and so on until the command is found.
If the command is not found on your path the message
command_name: command not found