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3.1.3 The online help system
The online help system is invoked by the help command.
? may be used as a synonym for help . Simply typing
help; displays the "top" of the help system (i.e., the title
page of the SINGULAR manual) which offers a
short table of contents. Typing help topic; shows the
available documentation on the respective topic. Here, topic may be either a function
name or, more generally, any index entry of the SINGULAR
manual. Furthermore, topic may contain wildcard characters.
See help, for more information.
Online help information can be displayed in various help browsers. The
following table lists a summary of the browsers which are always present.
Usually, external browsers are much more convenient:
A complete, customizable list can be found in the file LIB/help.cnf .
Browser | Platform |
Description
|
html |
Windows
| displays a html version of the manual in your default html browser
|
builtin |
all
| simply outputs the help information in plain ASCII format
|
emacs |
Unix, Windows
| when running SINGULAR within (X)emacs, displays help inside the
(X)emacs info buffer.
|
dummy |
all
| displays an error message due to the non-availability of a help browser
|
External browsers depend on your system and the contents of LIB/help.cnf ,
the default includes:
htmlview (displays HTML help pages via htlmview ),
mac (displays HTML help pages via open ),
mac-net (displays HTML help pages via open ),
mozilla (displays HTML help pages via mozilla ),
firefox (displays HTML help pages via firefox ),
konqueror (displays HTML help pages via konqueror ),
galeon (displays HTML help pages via galeon ),
netscape (displays HTML help pages via netscape ),
safari (displays HTML help pages on MacOsX via safari ),
tkinfo (displays INFO help pages via tkinfo ),
xinfo (displays INFO help pages via info ),
info (displays INFO help pages via info ),
lynx (displays HTML help pages via lynx ).
The browser which is used to display the help information, can be either
set at startup time with the command line option (see Command line options)
or with the SINGULAR command (see system)
The SINGULAR command
lists all available browsers and the command
returns the currently used browser.
If no browser is explicitly set by the user, then the first available browser
(w.r.t. the order of the browsers in the file LIB/help.cnf ) is chosen.
The .singularrc (see Startup sequence) file is a good place
to set your default browser. Recall that if a file
$HOME/.singularrc exists on your system, then the content of this
file is executed before the first user input. Hence, putting
| if (! system("--emacs"))
{
// only set help browser if not running within emacs
system("--browser", "info");
}
// if help browser is later on set to a web browser,
// allow it to fetch HTML pages from the net
system("--allow-net", 1);
| in your file $HOME/.singularrc sets your default browser to
info , unless SINGULAR is run within emacs (in which case the
default browser is automatically set to emacs ).
Obviously, certain external files and programs are required for the
SINGULAR help system to work correctly. If something is not available
or goes wrong, here are some tips for troubleshooting the help system:
-
Under Unix, the environment variable
DISPLAY has to be set for all X11
browsers to work.
-
The help browsers are only available if the respective programs are installed
on your system (for
xinfo , the programs xterm and
info are necessary). You can explicitly specify which program to
use, by changing the entry in LIB/help.cnf
-
If the help browser cannot find the local html
pages of the SINGULAR manual (which it will look for at
$RootDir/html -- see Loading a library for more info on
$RootDir ) and the (command-line) option --allow-net
has explicitly been set (see Command line options and
system for more info on
setting values of command-line options), then it dispatches the html
pages from
https://www.singular.uni-kl.de/Manual. (Note that
the non-local net-access of HTML pages is disabled, by default.)
An
alternative location of a local directory where the html pages reside
can be specified by setting the environment variable
SINGULAR_HTML_DIR .
-
The
info based help browsers tkinfo , xinfo , info , and
builtin need the (info) file singular.info which will be looked
for at $RootDir/info/singular.info (see Loading a library
for more info on $RootDir ). An alternative
location of the info file of the manual can be specified by setting the
environment variable SINGULAR_INFO_FILE .
Command line options
Info help browsers
The help browsers tkinfo , xinfo and info (so-called
info help browsers) are based on the
info program from the GNU texinfo package. See section `Getting started' in The Info Manual, for more
information.
For info help browsers, the online manual is decomposed into "nodes"
of information, closely
related to the division of the printed manual into sections and
subsections. A node contains text describing a specific topic at a
specific level of detail. The top line of a node is its "header".
The node's header tells the name of the current node (Node: ), the
name of the next node (Next: ), the name of the previous node
(Prev: ), and the name of the upper node (Up: ).
To move within info, type commands consisting of single characters. Do
not type RETURN . Do not use cursor keys, either. Using some of
the cursor keys by accident might pop to some totally different node.
Type l to return to the original node. Some of the info
commands read input from the command line at the bottom. The
TAB key may be used to complete partially entered input.
The most important commands are:
q
- leaves the online help system
n
- goes to the next node
p
- goes to the previous node
u
- goes to the upper node
m
- picks a menu item specified by name
f
- follows a cross reference
l
- goes to the previously visited node
b
- goes to the beginning of the current node
e
- goes to the end of the current node
SPACE
- scrolls forward a page
DEL
- scrolls backward a page
h
- invokes info tutorial (use
l to return to the manual or
CTRL-X 0 to remove extra window)
CTRL-H
- shows a short overview over the online help system (use
l to return
to the manual or CTRL-X 0 to remove extra window)
s
- searches through the manual for a specific string, and selects the node in
which the next occurrence is found
1 , ..., 9
- picks i-th subtopic from a menu
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