Paths and Environments Your "path" is the set of directories that Unix looks at for executable files. It checks these directories when you log in, then remembers all the files in them. CERI accounts are generally set so that standard places for executables are already in your path. If you add a new program then you need to do something like:

set path = ($path YOURNEWPATH)

First, don't forget the $path above else you "overwrite" your old path. You need the rehash to tell UNIX to update its list of executables for you. If you don't want to go through all that and don't mind typing, you can always type the path and filename.

The other principal paths to know about are MANPATH and LD_LIBRARY_PATH. MANPATH is where all the manpages live, and LD_LIBRARY_PATH tells the linker where to look for libraries and such. You shouldn't mess with the LD_LIBRARY_PATH unless you absolutely have to because some bad people create very different libraries of the same name and if you use the wrong one, you may get unpredictable results.

Environments are handy things that many programs use. There are tons of them. An example is HOME. Somewhere this environment was probably already defined for you. You can set it using something like:
setenv HOME /export/home/withers.

You can see what it is already set to using
printenv HOME, or echo $HOME.

And you can nuke it using unsetenv HOME. You can see all your environments by typing printenv. There are really too many of these things to discuss here but some principal ones are:
PRINTER (sets your default printer)
HOME (sets your home directory)
TERM (sets your terminal to something like xterm or sun-cmd).

But, if it works for the person sitting next to you and doesn't work for you, odds are it is some path or another or some environment or another that is different. Either that or the computer hates you probably because you tend to smudge the computer screen with your greasy fingers.