The help-system always writes its output to current_output
instead of user_output. This makes it possible to redirect
information produced by help/[0,1] or manual/[0,1] to a
file. For example, to save the documentation on assert/1 in a
file called assert.doc, type:
?- tell('assert.doc'), help(assert), told.
Furthermore, if the current_output is the same as
user_output (i.e. the terminal), then the environment
variable PAGER is used, if set, to display the information. If
PAGER is not set, the default pager, more, is used.
Under Emacs: This strategy is not applicable in the Emacs interface, which provides its own way of saving displayed text, nor in QUI.