Appendix M : Environment Variables
----------------------------------

UniPOPS uses a number of Unix environment variables.  Unix environment
variables are ways in which strings can be associated with a symbolic
name.  For example, if you usually store your data in a directory named
/home/bgarwood/data, then it would be useful to you if you could associate
that full path name with a shorter symbolic name, say MYDATA.  That way,
whenever you reference MYDATA the system understands you to mean the
full pathname.  The exact syntax for setting an environment variable
varies between the different types of Unix shells (csh, sh, bash, ksh, etc).

For all shells, if you want to see the current string associated with
an environment variable, you use the echo command and put a dollar
symbol, $, in front of the symbol name.  For example:

	% echo $MYDATA

would print "/home/bgarwood/data" on the screen if MYDATA was set to
that value as in the example above.

There are also several special symbols, for example:

	% echo $SHELL

will print the pathname of the shell you are using (e.g. "/bin/csh" for
the c-shell, "/local/bin/bash" for a local version of the bash shell, etc).

If you set a variable in one terminal or window, it will NOT be available
in any other windows that you may be running.

If you are using the c-shell, you would set an environment variable using
the setenv command:

	% setenv MYDATA /home/bgarwood/data

If you are using a shell with syntax compatible with the Bourne shell
(sh, bash, ksh, etc), you would set an environment variable using
something similar to the following:

	% export MYDATA=/home/bgarwood/data

Experienced Unix users will realize that a number of details have been
omitted or glossed over.  However, the above information should enable
users to understand the rest of this appendix as well as to determine
the current settings of the environment variables that UniPOPS uses.

New users are provided with a file named ".unipops" located in their
home directory.  The purpose of this file is to set the environment
variables that UniPOPS relies upon each time you log in to your 
account.  It is usually executed during login by one of the startup
"dot" files appropriate for your shell (.login, cshrc, .bashrc, .profile,
etc).  Its contents can be site-dependent and not all of the variables
described here need be set there.  The value that is important is always
the value that the variable has when you start using the program.  If
you change the value from the time to log in to the time you use
UniPOPS then it may differ from its value in your .unipops file.
If you change the value after you start up UniPOPS, that new value will
not affect the behavior of UniPOPS.  The only way that UniPOPS will use
the new value is to exit and restart the program.

The remainder of this document describes the primary environment variables
that UniPOPS uses (there are other variables, but most users should
be unaware of their use).

popseditor : 	The value of this environment variable is the editor that
		UniPOPS will use when you use the EDIT verb (e.g.
		vi, emacs, textedit, etc).

popswindow :    This should indicate the window manager you are using
		(options include "openlook", "sunview", "tvtwm", and
		"twm").  The use of this variable is site-dependent.

popsprinter:	This variable controls the printer used by the program
		for verbs that generate hardcopy (GCOPY, TCOPY, LASER, etc).
		It must be a printer found in the UniPOPS printer file.
		Look in the file $popsdir/printers for a complete
		listing of available printers.  If this value is not
		set at startup, you will be shown the list of available
		printers and asked to choose one.

popsversion:	This is used to construct popsdir.  It makes the version
		name more obvious.  Most users should set this to "old".
		Experienced users may want to set this to "test".  Staff
		users should always set this to "test".

popsdir    :	This indicates the full pathname of the top level directory
		where the version of UniPOPS that you will be using is
		located.  It must be terminated with a "/".

PATH	   :    This gives the search path that the shell uses to find
		commands that you type at the Unix prompt.  To use UniPOPS
		you must include $popsdir/bin and $popsdir/utilities
		some place in your path.

popsproc1  :    This is the first procedure directory.  It is searched by
		BATCH and EDIT if the requested file name is not found
		in the current directory.  It should be set to the 
		directory containing the standard UniPOPS procedures:
		$popsdir/procedures/.  It should be terminated with a "/".
		PRCDIR will display all files ending in .prc found in
		$popsproc1.

popsproc2   :   This is the second procedure directory.  It is searched by
		BATCH and EDIT if the requested file name is not found 
		in the current directory or $popsproc1.  It can be set
		to any directory or left unset (the default condition).
		If set, it should be terminated with a "/".  PRCDIR will
		display all files ending in .prc found in $popsproc2.
