pr-path-alist

pr-path-alist is a variable defined in `printing.el'.
Its value is

((unix PATH) (cygwin PATH) (windows PATH))

Documentation:
Specify an alist for command paths.

It's used to find commands used for printing package, like gv, gs, gsview.exe,
mpage, print.exe, etc. See also `pr-command' function.

Each element has the form:

(ENTRY DIRECTORY...)

Where:

ENTRY It's a symbol, used to identify this entry.
There must exist at least one of the following entries:

unix this entry is used when Emacs is running on GNU or
Unix system.

cygwin this entry is used when Emacs is running on Windows
95/98/NT/2000 with Cygwin.

windows this entry is used when Emacs is running on Windows
95/98/NT/2000.

DIRECTORY It should be a string or a symbol. If it's a symbol, it should
exist an equal entry in `pr-path-alist'. If it's a string,
it's considered a directory specification.

The directory specification may contain:
$var environment variable expansion
~/ tilde expansion
./ current directory
../ previous directory

For example, let's say the home directory is /home/my and the
current directory is /home/my/dir, so:

THE ENTRY IS EXPANDED TO
~/entry /home/my/entry
./entry /home/my/dir/entry
../entry /home/my/entry
$HOME/entry /home/my/entry
$HOME/~/other/../my/entry /home/my/entry

SPECIAL SYMBOL: If the symbol `PATH' is used in the directory
list and there isn't a `PATH' entry in `pr-path-alist' or the
`PATH' entry has a null directory list, the PATH environment
variable is used.

Examples:

* On GNU or Unix system:

'((unix "." "~/bin" ghostview mpage PATH)
(ghostview "$HOME/bin/gsview-dir")
(mpage "$HOME/bin/mpage-dir")
)

* On Windows system:

'((windows "c:/applications/executables" PATH ghostview mpage)
(ghostview "c:/gs/gsview-dir")
(mpage "c:/mpage-dir")
)

You can customize this variable.