The PATH is an environment variable that is a list of directories that the operating system looks in to find commands issued by the user. For example, when you type ls to list files, you are actually executing /bin/ls because the /bin directory is in your path by default.
Setting your Path
The syntax for setting your path is slightly dependent on which shell you are using. The default shell for RedHat 5.x and 6.x is the bash shell. Two other popular shells are tcsh and and csh called “t shell” and “c shell.” Thus, these 3 shells are covered here. If you are using a different shell, you can read the man pages by typing man “shellname” to find out the exact syntax. To find out which shell you are running, type the command finger “yourusername” such as “finger tchin” and look at the argument for “Shell:”
For bash shell:
For tcsh or csh:
set PATH = ($PATH /usr/sbin /usr/local/bin)
These commands can either be typed at the terminal each time you login, or you can add it to your .bashrc for bash shell or .cshrc for csh or tcsh so that each time you login, the PATH is already set. The $PATH means to keep the existing PATH and then append it with the other directories listed. This is helpful if a directory is set in the PATH by the System Administrator for everyone.