
                            Debian Menu System
                            ------------------

                   Joost Witteveen <joostje@debian.org>

                       Joey Hess <joeyh@debian.org>

                  Christian Schwarz <schwarz@debian.org>

                   Bill Allombert <ballombe@debian.org>

                         version 1.4, 31 May 2015


-------------------------------------------------------------------------------


Abstract
--------

     The `menu' package was inspired by the `install-fvwm2-menu' program
     from the old `fvwm2' package.  However, `menu' tries to provide a more
     general interface for menu building.  With the `update-menus' command
     from this package, no package needs to be modified for every X window
     manager again, and it provides a unified interface for both text- and
     X-oriented programs.


Copyright Notice
----------------

     Copyright (C)1997 Joost Witteveen, Joey Hess, Christian Schwarz.
     (C)2002-2005 Bill Allombert.

     This manual is free software; you may redistribute it and/or modify it
     under the terms of the GNU General Public License as published by the
     Free Software Foundation; either version 2, or (at your option) any
     later version.

     This is distributed in the hope that it will be useful, but _without
     any warranty_; without even the implied warranty of merchantability or
     fitness for a particular purpose.  See the GNU General Public License
     for more details.

     A copy of the GNU General Public License is available as
     `/usr/share/common-licenses/GPL' in the Debian GNU/Linux distribution
     or on the World Wide Web at `http://www.gnu.org/copyleft/gpl.html'.
     You can also obtain it by writing to the Free Software Foundation,
     Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA


-------------------------------------------------------------------------------


Contents
--------

     1.        Introduction

     2.        Menu from the viewpoint of a user
     2.1.      How/when do the window manager startup files get created?
     2.2.      Tuning of the generated window manager startup files
     2.3.      Optimization of menu tree: hints

     3.        The menu file
     3.1.      Location
     3.2.      Syntax
     3.3.      The `title' field
     3.4.      The `needs' field
     3.5.      The `section' field
     3.6.      The `command' field
     3.7.      The `icon' field
     3.8.      The `hints' field
     3.9.      Entries for menu sections.
     3.10.     Fvwm's task and title bars

     4.        What packages with applications should do
     4.1.      Providing a menu file
     4.2.      Adding a hook for dpkg in your packages

     5.        What packages with menu managers should do

     6.        How a user can override the menus
     6.1.      Configuring the menus
     6.2.      Specifying that a menu entry should not be displayed
     6.3.      Including other files

     7.        The internals of the menu package
     7.1.      The update-menus program
     7.2.      The install-menu program
     7.3.      The install-menu config script definitions
     7.4.      Hints, tree optimization

     8.        Variables and functions in the install-menu scripts
     8.1.      String constants
     8.2.      Variables
     8.3.      Functions


-------------------------------------------------------------------------------


1. Introduction
---------------

     Before the advent of `update-menus', when the sysadmin installed a
     package onto a Debian system, they would need to edit various window
     manager config files to make the new program show up on, for example,
     `fvwm''s menus.  The menus could easily become out of sync with what
     programs were actually available, with some menu items that didn't
     work, and other programs that lacked a menu entry.  update-menus and
     Debian's menu package aim to solve this problem.

     `update-menus' automatically generates menus of installed programs for
     window managers and other menu programs.  It should be run whenever a
     menu file or menu-method file is changed.  `update-menus' will be ran
     automatically when Debian packages that contain menu files are
     installed or removed from the system.  Users themselves can add/delete
     menu items, and should then run `update-menus' as that user, thus
     creating window-manager startup files that are used in preference to
     the systemwide files.

     One problem we ran into with menu-1.x (and before) was that the number
     of entries in any submenu vary wildly: on my system there are only two
     entries in `/Applications/Editors', while I'm sure that other people
     have more like 20 entries there.  Many people complained about the
     fullness of certain submenus, citing scientific studies or personal
     experience to explain why overfull or underfull submenus are a bad
     thing.  To overcome this, menu-2.0 now can optimize the tree itself,
     possibly subdividing for example the `/Applications/Editors' tree in,
     say `Editors/Beginner', `Editors/Experienced', or whatever, if there
     are many entries in that submenu, or maybe even totally removing
     `/Applications/Editors' on systems where there are few editors
     installed.  To be able to do this, menu follows the information
     supplied to it in the `hints' variables (see paragraph below, or the
     hints chapter).

     Each package that needs to add an entry to the menu tree, includes a
     menu file `/usr/share/menu/package-name'.  In this file, it will have
     one line per menu entry, like this (copied from
     `/usr/share/menu/xbase'):

             ?package(xbase):command="/usr/bin/xedit" needs="X11" \
                          section="Applications/Editors" title="Xedit" \
                          hints="Beginner,Small"

     This describes the type of interface Xedit needs (X11), the menu
     section the menu entry should be in, the menu text, and the command
     that should be executed.  Also, it tells menu that, if
     `/Applications/Editors' is overfull, it could put Xedit in a
     `Applications/Editors/Beginner' or `Applications/Editors/Small'
     subsection.

     Whenever `root' runs `update-menus', it will check all menu files in
     `/etc/menu', `/usr/lib/menu', `/usr/share/menu', and run the
     installation scripts that display managers like `fvwm2' should provide
     in `/etc/menu-methods'.

     The menu package itself provides a set of default menu files, for
     people to get the idea, and to speed up things a bit.  (These files
     should be incorporated into the package.)

     Note, that substantial and incompatible changes took place with the
     menu-1.0 release, while substantial features were added by the release
     of menu-2.0.  This document describes menu-2.0.  Menu-2.0 now doesn't
     accept the menu-methods written for menu-0.x, but for most window
     managers that still have those old menu-methods, I have put new style
     menu-methods in /usr/share/doc/menu/examples.  Everything written for
     menu-1.0 will work with menu-2.0.

     Most notable changes between menu-0.x and menu-1.x are listed in the
     file README.changes in the menu package, the features added by
     menu-2.0 can be summarised here: hints, and the menu-2 compat mode.
     (where lines are finished by a ';' instead of a newline).


-------------------------------------------------------------------------------


2. Menu from the viewpoint of a user
------------------------------------


2.1. How/when do the window manager startup files get created?
--------------------------------------------------------------

     Basically, users don't need to know any of how and when the startup
     files are created, but they might be interested to know anyway.

     When a package that wants to add something to the menu tree gets
     installed, it will run `update-menus' in its `postinst' script.
     Update-menus then reads in all menu files in `/etc/menu/',
     `/usr/lib/menu', `/usr/share/menu' and `/usr/share/menu/default', and
     stores the menu entries of all installed packages in memory.  Once
     that has been done, it will run the menu-methods in
     `/etc/menu-methods/*', and pipe the information about the menu entries
     to the menu-methods on stdout, so that the menu-methods can read this.
     Each window-manager or other program that wants to have the Debian
     menu tree, will supply a menu-method script in `/etc/menu-methods/'.
     This menu-method then knows how to generate the startup-file for that
     window manager.  To facilitate this task for the window-manager
     maintainers, menu provides a `install-menu' program.  This program can
     generate the startupfiles for just about every window manager.


2.2. Tuning of the generated window manager startup files
---------------------------------------------------------

     In principle this is a very window-manager specific business.  But for
     all window managers (and others) applies:

     The file to attack is the menu-method in `/etc/menu-methods/$wm', with
     `$wm' the name of your window manager.  However, if this menu-method
     `!include'-s the `menu.h' file (as it should), you can also edit that
     file, to make your changes work for every installed window manager.

     If the menu-method file of your window manager does `!include' the
     `menu.h' file, and makes proper use of the definitions in there, then
     you can look at the comments in that `menu.h' file to see how you can
     make minor adjustments to the look of your menus in your window
     manager.

     To generally change the menu tree, see the next section.


2.3. Optimization of menu tree: hints
-------------------------------------

     If `hint_optimize=true' has been set in a menu-method script
     (actually, that definition should appear in the `!include'-ed `menu.h'
     file), then install-menu will try to alter the menu tree, to make
     every submenu have about the optimum number of menu entries (as
     specified by `hints_nentry=...').  It will do that by removing
     under-full submenus (only if the `parent' of that submenu isn't itself
     already overfull), and by possibly creating new submenus, using hints.
     Note, however, that the optimization of the tree takes in principle
     exponential time, so menu speeds up the process, at the expense of
     occasionally not finding the best tree.  So, the tree you are
     presented with may not be optimal.  For tuning variables, see the
     hint_* variables in the last chapter.


-------------------------------------------------------------------------------


3. The menu file
----------------


3.1. Location
-------------

     Packages-provided menu files should be in `/usr/share/menu/', unless
     the menu files are actually executable binaries, in which case they go
     in `/usr/lib/menu/'.  System-local menu files should be in
     `/etc/menu/'.  User-specific menu files should be in `~/.menu/'


3.2. Syntax
-----------

     The format is:

          ?package(package[,package2,...]): \
             field1="value1"\
             field2="value2"\

     Here is an example to describe the syntax of such a file:

?package(gnumeric):\             specifies what packages need to be installed
                                 multiple requirements should be separated by
                                 comma
  needs="X11"\                   what kind of environment this command expects
  section="Applications/Office"\ in what section this menu entry should be
  title="Gnumeric"\              the title of the menu entry
  command="gnumeric" \           the command to run
  hints="Gnome,Spreadsheets" \   some hints about menu placement.
  icon="/usr/share/pixmaps/gnumeric.xpm"  the path to the icon to use.

     A number sign ("#") can be used to include comments.  An entry must be
     terminated by a newline; however you can use a backslash to escape a
     newline.

     Values must be quoted with ", and meta-characters (", backslash,
     newline) must be escaped with a backslash.

     You can include several entries in the same file.

     The file must be encoded in 7-bit ASCII.  This is necessary to
     accomodate window managers that do not support 8-bit encodings.
     However the translations are not limited in encoding.

     `?package(...)' contains a comma-separated list of packages that need
     to be installed for the menu entry to be displayed.  That should
     include the package containing the menu file and any packages
     necessary to run the command not depended on by the package nor
     essential.  Users can use pseudo-package names starting with
     "`local.'" which are assumed to be always installed.

     The fields `needs', `section', `title' and `command' are mandatory.
     Other fields are optional.  Custom fields are supported, so you can
     add new fields for you own purpose.  If a field is specified multiple
     times in a menu entry, the last instance will be used.


3.3. The `title' field
----------------------

     The `title' must follow the following requirements:

     1.   It must be short.  There is an optional `longtitle' field for
          users that want longer titles.

     2.   It must be properly capitalized.  Use _Emacs_ and not _emacs_.

     3.   It must be unique.  Two entries must not have the same title.


3.4. The `needs' field
----------------------

     The following `needs' are documented for use in the Debian menu.

     1.   `X11': if this program runs under X11.

     2.   `text': if it runs under a terminal.  X11 window managers will
          spawn an X terminal emulator.

     3.   `vc': if it runs under a linux virtual console but not under a X
          terminal emulator.

     4.   `wm': if it is a X11 window manager.  The current window manager
          will exec(2) this program to avoid "Another window manager is
          running" errors.

     A menu manager can use a special `needs' value reflecting the menu
     manager name for menu entries that must only be displayed in this menu
     manager.  Examples include `fvwm' modules, `dwww' menu entries.

     A program like gnuplot which can be run on X11 as well as on a text
     terminal should _not_ have an extra entry with `needs=X11' with an
     hard-coded call to an X terminal emulator, because this would defeat
     the configuration mechanism of menu that allow to choose which window
     manager is called.

     On the other hand, if a program (like `emacs') can be run as real X
     application as well as in a terminal, two entries should be listed,
     otherwise the program will always be run in an `xterm' (or `rxvt').
     However, two entries are not allowed to have the same title.  The
     title must be unique.


3.5. The `section' field
------------------------

     The `section' field holds a slash-separated list of hierarchical
     sections components.

     The _authoritative list of Debian's menu structure_ is maintained in
     the Debian Menu sub-policy document which is part of the Debian Policy
     package.  The current menu structure was drafted in 2006 by Linas
     Zvirblis with input from the debian-devel mailing list.

     The menu structure below is included only for convenience and is not
     authoritative.  If it disagrees with the structure in the Debian Menu
     sub-policy, please send a wishlist bug to the `menu' package.

     Packages must be placed in leaf sections.  Please do _not_ put your
     packages into any other sections.

     Applications
          Normal applications

          Accessibility
               Tools to aid people with disabilities or for machines
               lacking usual input devices.

               Examples: gok, yasr, dasher.

          Amateur Radio
               Anything relating to HAM radio.

               Examples: baken, hamsoft, twlog

          Data Management
               Interactive database programs, collection managers, address
               books, bibliography tools, etc.

               gaby, alexandria, mdbtools

          Editors
               Editors, other than office word processors, for text-based
               information.

               Examples: ksubtile, nano, hexedit

          Education
               Educational and training softwares.

               Examples: gtypist, gcompris, quiz

          Emulators
               Software that allows you to run non-native software or more
               than one OS at a time.

               Examples: wine, dosemu, qemu

          File Management
               Tools for file management, archiving, searching, CD/DVD
               burning, backup, etc.

               Examples: file-roller, mc, baobab

          Graphics
               2D and 3D graphics manipulation software.

               Examples: gimp, inkscape, imagemagick

          Mobile Devices
               Software that allows you to interface with mobile devices
               (phones, PDAs, etc.).

               Examples: kandy, gnokii, gnome-pilot

          Network
               Network related software.  This is a three-level section, do
               not put entries directly here.

               Communication
                    Mail, USENET news, chat, instant messaging, IP
                    telephony, video conferencing software, etc.

                    Examples: xchat, gaim, mutt

               File Transfer
                    File transfer software such as download managers, FTP
                    clients, P2P clients, etc.

                    Examples: amule, gftp, d4x

               Monitoring
                    Network monitoring software

                    Examples: gip, ettercap, iptstate

               Web Browsing
                    Web browsers, tools for offline browsing, etc.

                    Examples: elinks, epiphany-browser, webhttrack

               Web News
                    Web feed (RSS, Atom, etc.) and podcast aggregators.

                    Examples: akregator, kitty, liferea

          Office
               Office suites, word processors, spreadsheets, CRM, ERP,
               financial sofware, etc.

               Examples: openoffice.org, tinyerp-client, gnucash

          Programming
               IDEs, debuggers, etc.

               Examples: anjuta, gdb, eclipse

          Project Management
               Timetable managers, group task trackers, bug tracking
               software, etc.

               Examples: planner, bugzilla, gnotime

          Science
               Scientific and engineering-related software.

               Astronomy
                    Astronomy-related software.

                    Examples: celestia, spacechart, stellarium

               Biology
                    Biology-related software.

                    Examples: arb, ncbi-tools-x11, seaview

               Chemistry
                    Chemistry-related software.

                    Examples: chemtool, kalzium, xdrawchem

               Data Analysis
                    Software designed for processing, extracting, and
                    presenting generic scientific data.

                    Examples: fityk, ygraph, mn-fit

               Electronics
                    Circuit design tools, simulators and assemblers for
                    microprocessors, etc

                    Examples: geda, gnucap, tkgate

               Engineering
                    CAD, UML tools, diagram-drawing and other
                    engineering-related software.

                    Examples: tcm, dia, qcad

               Geoscience
                    Geoscience-related software.

                    Examples: earth3d, qgis, therion

               Mathematics
                    Mathematics-related software.

                    Examples: gcalctool, snappea, xeukleides

               Medicine
                    Medicine-related software.

                    Examples: mssstest, gnumed-client, xmedcon

               Physics
                    Physics-related software.

                    Examples: kxterm, ifrit, paw

               Social
                    Social sciences-related software.

                    Examples: gnomesword, hanzim, bibletime

          Shells
               Various shells to be used inside a terminal emulator.

               Examples: bash, ksh, zsh

          Sound
               Sound players, editors, and rippers/recorders.

               Examples: beep-media-player, grip, audacity

          System
               System related software.

               Administration
                    Administrative and system configuration utilities, also
                    tools for personal user settings.

                    Examples: gnome-control-center, configure-debian, gksu

               Hardware
                    Tools for manipulating specific hardware, especially
                    non-standard laptop hardware.

                    Examples: toshutils, nvclock-gtk, nvtv

               Language Environment
                    This section is reserved for language-env as a special
                    case.

               Monitoring
                    System information and monitoring tools, log viewers,
                    etc.

                    Examples: top, hal-device-manager, gtkdiskfree

               Package Management
                    Package managers and related tools.

                    Examples: aptitude, deborphan, smartpm

               Security
                    Security, cryptography and privacy related software,
                    antiviruses, tools to track and report bugs, etc.

                    Examples: gpgkeys, bastille, avscan

          Terminal Emulators
               Graphical terminal emulators.

               Examples: xterm, gnome-terminal, rxvt

          Text
               Text oriented tools like dictionaries, OCR, translation,
               text analysis software, etc.

               Examples: kdrill, stardict, turkey

          TV and Radio
               TV-in, TV-out, FM radio, teletext browsers, etc.

               Examples: gradio, gatos, alevt

          Viewers
               Software for viewing images, documents and other (non-video)
               media.

               Examples: gqview, evince, gthumb

          Video
               Video players, editors, and rippers/recorders.

               Examples: istanbul, totem, kino

          Web Development
               Software for web site editing, web programming, and site
               administration.

               Examples: bluefish, screem, gphpedit

     Games
          Games and recreations

          Action
               Games that involve a lot of action and require fast
               reflexes.

               Examples: xsoldier, supertux, xmoto

          Adventure
               Role playing and adventure games, interactive movies and
               stories, etc.

               Examples: beneath-a-steel-sky, egoboo, kq

          Blocks
               Tetris-like games involving falling blocks.

               Examples: crack-attack, frozen-bubble, netris

          Board
               Games played on a board.

               Examples: phalanx, xshogi, xboard

          Card
               Games involving a deck of cards.

               Examples: pysol, ace-of-penguins, xpat2

          Puzzles
               Tests of ingenuity and logic.

               Examples: xmpuzzles, sgt-puzzles, enigma

          Simulation
               Simulations of the real world in all detail and complexity.

               Examples: flightgear, torcs

          Strategy
               Games involving long-term strategic thinking.

               Examples: wesnoth, widelands, netpanzer

          Tools
               Server browsers, configurators, editors, and other
               game-related tools that are not games themselves.

               Examples: xqf, crystalspace

          Toys
               Amusements, eye-candy, entertaining demos, screen hacks
               (screensavers), etc.

               Examples: xdesktopwaves, xphoon, xpenguins

     Help
          programs that provide user documentation

          Examples: debian-reference, apt-howto, dhelp

     Screen
          Programs that affect the whole screen.

          Saving
               Tools for blanking the screen.  Entries of screen hacks and
               configuration GUIs should go to other appropriate sections.

               Examples: xscreensaver, xlockmore

          Locking
               Tools for locking the screen.

               Examples: xscreensaver, xlockmore

     Window Managers
          X window managers.

          Examples: fluxbox, metacity, waimea

     FVWM Modules
          FVWM-based window manager modules.  As only modules related to
          the running window-manager are displayed, do not create
          subsections for specific window-managers.

          Examples: fvwm, fvwm-gnome, fvwm95

     Window Maker
          This section is reserved for wmaker as a special case.

          All wmaker specific entries must go here.

     Users wanting to access some menu entries quickly can also put them in
     the root menu.  This is done by using _section="/"_.  Package-provided
     menu entries must never use this feature.


3.6. The `command' field
------------------------

     The command field holds the command that should be executed when the
     menu entry is selected.  Commands will be executed with `sh -c' using

          execl("/bin/sh","sh","-c",command)

     or the equivalent.


3.7. The `icon' field
---------------------

     Please make sure the icons you specify are always available on the
     system.  So, if you want to have an icon with your menu entry, the
     preferred method is to supply the icon with that package.  Icons
     should generally be installed in the directory `/usr/share/pixmaps'.

     Debian package maintainers should ensure that any icons they include
     for use in the Debian menus conform to the following points:

     1.   The icons should be in xpm format.

     2.   The icons may not be larger than 32x32 pixels, although smaller
          sizes are ok.

     3.   The background area of the icon should be transparent, if
          possible.

     You can provide both 16x16 and 32x32 pixels icons using the variables
     icon16x16 and icon32x32 so that the user can configure menu to use one
     or the other.

     If you, as a system administrator, don't like the icons in the menus,
     simply change the `icon()' function from the file
     `/etc/menu-methods/menu.h', and run `update-menus'.


3.8. The `hints' field
----------------------

     Hints are used to help menu structure generated menus in a more
     optimal way.  For example:

          ?package(emacs20):\
            needs="x11"\
            hints="Big,Expert,Featureful" \
            section="Applications/Editors"\
            title="Emacs 20"\
            command="/usr/bin/emacs20"\
            icon=/usr/share/emacs/20.3/etc/emacs.xbm

     The above hints will tell `menu' to consider grouping `emacs' together
     with other editors that are marked similar.  For example, if `vi' on
     your system has a hints="Small,Expert" definition, and there are too
     many entries in the `/Applications/Editors' menu entry, then menu will
     consider creating a `/Applications/Editors/Expert' submenu, and put
     both `vi' and `emacs' in it.  (Of course, only if you have
     `hint_optimize=true' in your `/etc/menu-methods/menu.h' file).


3.9. Entries for menu sections.
-------------------------------

     It is possible to add entries for menu sections, but it is not
     mandatory since section entries are created automatically.  However,
     this allows to specify fields for sections like `icon' and `sort'.
     The syntax for menu sections entries is the same as for regular
     entries, the `section' field holding the name of the parent section.
     For example

?package(local.games): needs="text" title="Games" section="/" sort="001"

     will sort `Games' first.


3.10. Fvwm's task and title bars
--------------------------------

     The problem with the stuff in the task bar is that all items are
     displayed all of the time.  So, if 1500 Debian packages all were to
     register a button, the buttons would quickly fill the screen, making
     the exercise useless.  The few applications that are considered
     important enough to be listed in the task bar usually vary widely on
     each system, making it impossible to select a ``happy few'' apps that
     are allowed there on every Debian system.  If you (as a local system
     administrator) want your `fvwm2' to have a few buttons, you can
     install files for those packages in `/menu/$package', containing a
     menu entry like this:

            ?Package(xmball):needs=button\
                          section=Games/Puzzles\
                          icon=path-to-pixmap.xpm\
                          title="Xmball"\
                          command=/usr/games/xmball

     Then, do the following:

            cd /etc/menu-methods/
            cp fvwm2 fvwm2button
            vi fvwm2button

     and remove all the "supported" entries, adding the one below.  For the
     rest, leave everything the same except those listed below.

  supported
    button="+ Style \"" $title "\" TitleIcon" $icon " Exec "  $command "\n"
  endsupported
  startmenu:   "AddToTitlebar \n"
  endmenu:     "\n"
  submenutitle:""
  mainmenu:
  genmenu:   "buttondefs.hook"

     (Of course regular users (not system administrators) can also specify
     `buttonfiles' in their ~/.menu/ directory).


-------------------------------------------------------------------------------


4. What packages with applications should do
--------------------------------------------


4.1. Providing a menu file
--------------------------

     A package should provide a menu file `/usr/share/menu/<package-name>'
     that contains information about each program it likes to make
     available in the menus.


4.2. Adding a hook for dpkg in your packages
--------------------------------------------

     The `postinst' script and the `postrm' script of the package should
     include the line

           if test -x /usr/bin/update-menus; then update-menus; fi

     If you are using `debhelper', the program `dh_installmenu' can do it
     for you.


-------------------------------------------------------------------------------


5. What packages with menu managers should do
---------------------------------------------

     Each package containing a _menu manager_ (i.e., a program that can
     display a menu) should provide a script or program in
     `/etc/menu-methods/' that can read the menu files.  This script will
     be executed by `update-menus', which will feed the menu entries to be
     installed to your script via standard input (stdin).

     The scripts in `/etc/menu-methods/' should be configuration files, so
     the user can tune the behaviour of the script, and they must always
     include the `/etc/menu-methods/menu.h' configuration file at the
     beginning with the command `!include menu.h' For the same reason,
     scripts in `/etc/menu-methods/' are requested to use the following
     configurable functions: `title()' for the title (in place of
     `$title'), `icon()' for the icon (in place of `$icon'), `term()' for
     running `text' command under `X11'.  `sections_translations()' for the
     list of translations of sections name available.  This later one is
     only defined if you `!include lang.h'

     Good examples for these scripts for nearly all Debian window managers
     are included in the `menu' package in `/usr/share/doc/menu/examples'.
     Note that while working on your script, you can use the tricks
     described in "The internals of the menu package", section "The
     update-menus program", to run just your script, instead of having
     update-menus run all scripts (can save quite a lot of time).

     This script should not be executable in the package.  Instead the
     `postinst' should add the execute bit and then run `update-menus' (if
     it is executable).

     Similarly, the `postrm' script when called with option ``remove''
     should remove the execute bit and run `update-menus' (if it is
     executable).

     Here is an example of such a `postrm' script using `sh':

  #!/bin/sh
  set -e
  inst=/etc/menu-methods/#PACKAGE#
  case "$1" in
     remove)
        if [ -f $inst ]; then
                chmod a-x $inst
                if [ -x /usr/bin/update-menus ]; then update-menus ; fi
        fi
     ;;
     purge)
         #remove the files that install-menu creates:
         rm -rf /var/lib/foo-wm/menu
     ;;
     upgrade);;
     *)
         echo "postrm called with unknown argument \`$1'" >&2
         exit 0
     ;;
  esac

     And here is a good example for a `postinst' script:

            #!/bin/sh
            set -e
            inst=/etc/menu-methods/#PACKAGE#
            if [ -f $inst ]; then
                chmod a+x $inst
                if [ -x /usr/bin/update-menus ]; then
                    update-menus
                fi
            fi

     If you are using `debhelper', the program `dh_installmenu' can help
     you do it.

     Please, do not make your package _depend_ on the menu package!  The
     preferred way of telling dpkg that your wm can cooperate with menu is:

             Suggests: menu

     Please only consider using "depends" if you feel providing reasonable
     defaults for systems without `menu' will make life very difficult for
     you.


-------------------------------------------------------------------------------


6. How a user can override the menus
------------------------------------


6.1. Configuring the menus
--------------------------

     Users can specify their own menu entries in the `~/.menu' directory.
     The files can have an arbitrary file name as long as the new syntax
     for the menu entries is used.  They should start with either

            ?package(installed-package):

     or

            ?package(local.mystuff):

     if it's something that isn't ``debian-officially'' installed.  (Any
     ``package'' that starts with ```local.''' is considered installed.)

     If users want to have their own menu methods, they should create a
     `~/.menu-methods' directory and put all their menu methods in it.  (If
     `~/.menu-methods' exists, `/etc/menu-methods' will not be searched
     when a user runs `update-menus').

     A system administrator should place system-wide menu entries in
     `/etc/menu' (not in `/usr/share/menu/package', since these files will
     probably be overwritten by a package upgrade).


6.2. Specifying that a menu entry should not be displayed
---------------------------------------------------------

     If a user wants to remove the entries of `package' from the system
     menu then this will do the trick:

            echo -n  > ~/.menu/package

     The zero-size file will tell `update-menus' that the corresponding
     package should not have any menu entries listed.  A system
     administrator can remove menu entries system-wide with

            echo -n  > /etc/menu/package


6.3. Including other files
--------------------------

     <Historical comment by Joost:>

     <More out of curiosity than anything else, I recently read the KDE
     mailing list.  In it I saw some discussion about how good the Debian
     menu system is (whow, thanks, guys!), but one person found a missing
     feature: s/he said you couldn't include other files in the user menu
     files.  Well, actually, it was already possible, but not very well
     documented.>

     To include the contents of the file `/usr/share/menu/somefile', add
     this to your menu file:

          !include /usr/share/menu/somefile

     Apart from that, it is of course possible to make the menu entry file
     executable (`chmod a+x ~/.menu/package'), and do something like

          #!/bin/sh
          cat  /usr/share/menu/somefile
          sed -e  "/unwanted_entry/s/?package(/?package(notinstalled./" \
               /usr/share/menu/someotherfile

     to get the same effect, with the added flexibility of being able to
     filter out unwanted lines.


-------------------------------------------------------------------------------


7. The internals of the menu package
------------------------------------


7.1. The update-menus program
-----------------------------

     On startup, update-menus checks the file `/var/run/update-menus.pid'
     and the pid in it.  If there's an `update-menus' process with that pid
     it kills it.  If `/var/lib/dpkg/lock' exists, it checks to see if dpkg
     supports triggers.  If so, it uses dpkg-trigger to trigger a real
     update-menus run later.  Otherwise, it forks to background and returns
     control to dpkg.  The background process checks the
     `/var/lib/dpkg/lock' file approx.  every two second until the file's
     gone.

     Once it's decided to run, whether in the background after dpkg exits,
     or in the foreground when used with a trigger-capable dpkg,
     `update-menus' reads the menu-entry files in the following
     directories: `/etc/menu', `/usr/lib/menu', `/usr/share/menu',
     `/usr/share/menu/default'.  (if a user runs `update-menus', it will
     add `~/.menu' to the front of that list).  For every menu entry line
     in each file it checks if the corresponding package is installed.  The
     menu entries of all packages marked as installed by dpkg are added
     together in one big buffer that is kept in memory (exception:
     executable menu entry files are executed, and stdout is placed in the
     buffer).

     Once it's read all menu entry files, `update-menus' starts all
     executable scripts in `/etc/menu-methods/', hands the scripts the
     previously created buffer via stdin.  (If `update-menus' is run by a
     user, it will first try to run the scripts in `~/.menu-methods', and
     only if that directory doesn't exist, it will run the scripts in
     `/etc/menu-methods').

     Note that as an aid to debugging, one can use

          update-menus --stdout > /tmp/menu-stdin

     and then view the file `/tmp/menu-stdin' to see exactly what
     `update-menus' handed the menu-methods on their stdin.

     This may also be useful for people writing `/etc/menu-method/*'
     scripts: Running `update-menus' every time you changed something in
     the script may be quite time-consuming.  So, it's much easier to run
     `update-menus --stdout' once, and then run

            /etc/menu-methods/mymethod < /tmp/menu-stdin

     (and, if that also takes too long, just try editing /tmp/menu-stdin,
     and removing 90% or so of all entries)


7.2. The install-menu program
-----------------------------

     The files `/etc/menu-methods/$wm' are executable config files that
     start with the line

            #!/usr/bin/install-menu

     and thus start that program, handing it the configuration file for the
     specific window manager in the first command line argument.  This
     configuration consists of:

     1.   the compatibility mode ("menu-1" or "menu-2").

     2.   where the various files should be stored/read.

     3.   what "needs" are supported, and what wrapper files should be used
          for each "type".

     4.   how to remove the generated menu files.

     See `/usr/share/doc/menu/examples/' of the menu package for more
     comments.

     Options to `install-menu':

            --remove  Remove the menu files instead of generating them.
            --verbose Output outline of operations that are performed.

     Some window managers don't support an `include'-like statement in
     their `system.*rc' files (like `m4' or `cpp' preprocessing); they
     cannot read the `menudefs.hook' file generated by install-menu from
     their `system.*rc' config file.  To still be able to use them,
     `install-menu' will copy the file `$path/$examplercfile' to
     `$path/$rcfile' (with `$examplercfile' and `$rcfile' defined in the
     `install-menu' config file, and `$path' either the `$rootprefix' or
     `${HOME}/$userprefix', depending on whether root or user executed the
     file.), and replace all occurrences of ``install-menu-defs'' with the
     `$genmenu' file it just generated.

     As an example, consider the following:
     `examplercfile=system.foo-wm-example', `rcfile=system.foo-wm',
     `genmenu=menudefs.hook' and `rootprefix=/var/lib/foo-wm/menu'.  Now,
     if `install-menu' gets run, it will first generate the file
     `/var/lib/foo-wm/menu/menudefs.hook'.  Next, it will line-by-line read
     the file `/var/lib/foo-wm/menu/system.foo-wm-example' and copy its
     contents to `/var/lib/foo-wm/menu/system.foo-wm', replacing every
     occurrence of the string `install-menu-defs' with the contents of the
     file `/var/lib/foo-wm/menu/menudefs.hook'.

     To activate the file copying in this way, simply define the
     `$examplercfile' and `$rcfile' variables in the `install-menu'
     configuration file (for example, see `/etc/menu-methods/fvwm'), and
     make sure there is a `$path/$examplercfile' (`$path' being either
     `$rootprefix', or `$userprefix'.)

     If you are writing a menu method, you can use the following to make
     debugging it somewhat more easily:

     1.   use `update-menus --stdout > /tmp/menu-stdin' to create a list of
          menu entries in `/tmp/menu-stdin' and then

     2.   you can run just your menu-method with (if it's called wm):

                 ./wm -v < /tmp/menu-stdin


7.3. The install-menu config script definitions
-----------------------------------------------

     The menu-methods in `/etc/menu-methods/*' are basically made up of a
     lot of ``tag=string'' definitions, telling `install-menu' how to
     generate a `system.${wm}rc' script.  This way you can tune the look of
     generated `system.${wm}rc' to your needs.

     In the following, something like

            treewalk="c(m)"

     means that the treewalk variable by default has the value "c(m)".

     For examples of what these scripts can look like, see
     `/usr/share/doc/menu/examples/*'.

     `compat="menu-1"'
          Two mode are defined:

          `"menu-1"'
               menu directives are terminated by an end-of-line character.

          `"menu-2"'
               menu directives are terminated by a semicolon character.

          This must be just after the `!include "menu.h"' directive so that
          `menu.h' can use its own compat mode.

     `outputencoding="UTF-8"'
          Set the encoding used for output files.  Use `iconv --list' to
          get the list of supported encoding.  Useful values include
          "UTF-8" and "ISO-8859-1".  The special value "LOCALE" means that
          the current locale encoding will be used.  If set to an empty
          string, no translations are performed.  This is the default.

     `outputlanguage=""'
          If set to "C" automatic translations will be disabled.  Note that
          you can still use translate() to perform explicit translation.

     `supported'
     `endsupported'
          Between the `supported' and `endsupported' keywords you define
          what "needs" are supported by this window manager.  So, the
          following is an example for a wm that supports both needs=x11 and
          needs=text:

                 function q($s) = "\"" esc($s,"\\\"") "\""
                 supported
                   x11 =" ShowEntry(" q(title()) ", " q($command) ")"
                   text=" ShowEntry(" q(title()) ", " q(term())   ")"
                 endsupported

          For the variable substitution (and functions, not shown above),
          see the next paragraph.  In the above example, you'll notice that
          for the menu entries that "need=text", the term() function is
          used.  This is a user-supplied function that will run $command in
          a X terminal emulator.  Also, as X11 is higher up in the
          supported list above than text, a package that supplies both a
          "needs=X11" and a "needs=text" entry will have the needs=X11
          entry installed, in favour of the needs=text entry.  You can
          continue lines on the next line with a backslash ("\"), but make
          sure you don't add any spaces after the backslash.

     `startmenu=""'
     `endmenu=""'
     `submenutitle=""'
          These define what to print for the beginning/end of a menu, and
          how to the print a menu entry that pops up another menu.  They
          are substituted the same way as the "supported" stuff is; see
          next paragraph.

     `treewalk="c(m)"'
          This string defines in what order to dump the `$startmenu',
          `$endmenu', and `$submenutitle' (and its children).  Each char in
          the string refers to:

    c  : dump children of menu.
    m  : dump this menu's $submenutitles
    (  : dump $startmenu
    )  : dump $endmenu
    M  : dump all $submenutitles of this menu and this menu's children.

          The default is "c(m)".  For olvwm, one needs: "(M)"

     `genmenu=""'
          The menu file to generate (usually something like
          `system."$wm"rc').  The file itself may depend on the level or
          title that is currently being worked on, like

                   genmenu="/subdir/" replacewith($section," ","_") "/rc.menu"

          (Substitution works just like in the supported stuff, see above).
          Note that the files made this way are truncated upon opening, so
          if you have a genmenu like the example above, then your
          `endmenu=' will override the startmenu stuff (but you probably
          only need one of the two anyway).

     `rootsection="/Debian"'
          the prefix every `$section' variable gets.

     `prerun=""'
     `postrun=""'
          The commands to run before and after, respectively, the actual
          generation of the `menudefs.hook' (genmenu) file.  Commands will
          be executed by `sh'.  Example:

                 prerun="rm -rf " prefix() "/*"
                 postrun="killall -USR1 fvwm2"

          (Substitution works just like the supported stuff, see below).

     `preruntest=""'
          Just like prerun, but if the return value of the command is
          non-zero, menu will quit.

     `also_run=""'
          If non-zero, install-menus will, after generating the output
          files, also load the file also_run, and use the new assignments
          to treewalk, genmenu, etc.  to generate more output.  This second
          time, variables like `prerun' and all of the hint stuff are
          ignored.

     `removemenu=""'
          The command to run when the menu-method is invoked with the
          option `--remove'.  This should remove all the autogenerated menu
          files.  If this option is not present, then install menu will
          remove `genmenu' if it is a constant string and `rcfile' if it is
          defined, and try to remove `prefix()' if it is empty.

     `onlyrunasroot=false'
     `onlyrunasuser=false'
          If `onlyrunasroot' is set to true, `install-menu' will quit
          silently when run as a user.  Similarly for `onlyrunasuser'.
          <`onlyrunasroot' is deprecated since it is simpler to just not
          define `userprefix'.> On the other hand, `onlyrunasuser' might be
          needed if you use `rcfile' since `rootprefix' is used as a
          fallback location for the template.

     `preoutput="#Automatically generated file. Do not edit (see
     /usr/share/doc/menu/html)\n\n"'
     `postoutput=""'
          Text to put at the beginning resp.  end of the generated file
          ($genmenu).

     `command=""'
          A command to run instead of `install-menus'.  This command used
          to be needed to get around limitations due to compatibility
          stuff.  But that compatibility with pre menu-1 stuff has been
          dropped, and isn't needed any more.

          Example:

                 command="cat > /tmp/menu-stdin"

     `hotkeyexclude=""'
          Keys not to use for hotkey generation.  You can use the same
          variables and functions here as in for example the startmenu
          sections.

          Example:

                 hotkeyexclude="q" $section

     `hotkeycase="insensitive"'
          can be either "insensitive" or "sensitive".  Determines whether
          the hotkeys can be of mixed case (`fvwm2' reads the hotkeys
          case-insensitive, `pdmenu' case-sensitive).  In case of the
          titles "Xa" and "xb", hotkey case-insensitive will generate "X"
          and "b", whereas case-sensitive would generate "X" and "x".

     `sort=$sort ":" $title'
          Entries within one menu will be alphabetically sorted by whatever
          sort returns.  So, if you do `sort=ifelse($command, "1",
          "0"):$title', then all submenus will appear above the commands in
          a submenu.  (A submenu always has `$command=""').  Or, as Joey
          Hess writes:

  You can add another field to the menu items, with whatever name you like,
  let's say it's called priority. Then add this line to
  /etc/menu-methods/*:

  sort=ifelse($priority, $priority, "9")

  This has the result of sorting things so items with a low priority sort to the
  top, and items with no priority default to priority 9 and sort to the bottom.

  (Note that it compares the strings alphabetically, not numerically.)

     `rcfile=""'
          If the window manager doesn't support an "include filename" or
          "read(filename)" statement in it's config file, you can rename
          the wm's config file to `system."$wm"rc-menu', and insert a
          "install-menu-defs" line (without the quotes, or whitespace
          around it, and "install-menu-defs" must be the only thing on the
          line) in the `system."$wm"rc-menu' file.  This will then get
          replaced by the `$genmenu' file that was just created (see also
          `$examplercfile').

     `examplercfile=""'
          if needed (see `rcfile'), this is the `system.rc"$wm"-menu' file.
          In that case, make `rcfile=system.rc"$wm"'.

     `rootprefix=""'
          The prefix to use when running as root (applies to $genmenu,
          $rcfile, $examplercfile and other old cache files).  If it is not
          defined, the menu-method will be skipped when run as root.

     `userprefix=""'
          As `rootprefix', but when running as user.  userprefix is
          relative to the user home directory, unless it start with 2
          slashes, in which case it is treated as an absolute path.  If it
          is not defined, the menu-method will be skipped when run as a
          user.

     `hint_optimize=false'
          If set to true, menu will try to generate an `optimal' tree,
          using the variables below.  If set to false, menu will keep the
          sections as they are specified in the menu entry files (and
          ignore any hint stuff).

     `hint_nentry=6'
          Optimal number of entries in a submenu.  It's a float, so you can
          set it to 5.5 if you cannot decide between 5 and 6.  Also, values
          less than 3 probably don't work very well at the moment.

     `hint_topnentry=5'
          Same as hint_nentry, but for the top level menu.  Often here are
          other entries, added by the window-manager itself (like Exit,
          Xterm, whatever) that menu doesn't know about, so that you may
          want to instruct menu to put less entries in the top level menu.

     `hint_mixedpenalty=15.0'
          Penalty for `mixed' menus.  Mixed menus are those with both
          submenus and direct commands in them.

     `hint_minhintfreq=0.1'
          Minimal relative frequency for the hints before they are
          considered.  Internal variable to speed up the tree generation.
          If you find menu slow, increase this value (to, say 0.2 or 0.3).

     `hint_mlpenalty=2000'
          `max local penalty', while evaluating the possible trees, menu
          gives `penalties' for submenus that don't contain the desired
          number of submenus.  The penalty is sqrt(n_entry_opt-n_entry),
          and eventually will be calculated as a sum of all nodes.  But to
          speed things up, menu will discard possibilities in which any
          node has a `local' penalty of more than hint_mlpenalty.  Increase
          this value if you think menu is overlooking your favorite tree
          (also decrease minhintfreq), decrease this value if you think
          menu is wasting too much time.  Because of hint_max_ntry, the
          influence of this variable is nearly zero nowadays.

     `hint_max_ntry=4'
          menu will recursively, for each node, try the hint_max_ntry best
          local menu-divisions.

     `hints_max_iter_hint=5'
          The search for what hints to use in one menu is rather expensive.
          But due to the way things are sorted, menu seems to always find
          the `best' match in the first 2% of iterations.  Thus, a way to
          speed things up is simply to cut of menu searching after `some'
          iterations are done.  This value controls this, and limits the
          number of iterations to
          5+hint_max_iter_hint*number_of_possible_hints.  Set this value to
          negative to disable this.

     `hint_debug=false'
          Set to true if you want to see loads and loads of debug output.


7.4. Hints, tree optimization
-----------------------------

     The hints actually work in a rather strange way: when
     `hint_optimize=true' then all `$section' elements are added to the
     specified `$hints' variable, and the order (`/Applications/Editors' or
     `/Editors/Applications') of the resulting hints is completely ignored.
     Then, the hints for each menu entry are handed to the optimization
     routine, which will calculate a reasonable tree for those hints.  That
     tree must comply with the following:

     When a user looks for a program "Program" with, say, hints
     "Good,Bulky,Heaven", then, while walking through the tree, it should
     at every node visited be clear for the user what submenu to select (or
     the menu should have "Program" directly in it).  So, the top-level
     menu may look like

            Good
            Hell
            Microsoft

     because then a searcher for a menu entry with hints
     "Good,Bulky,Heaven" will know to select the submenu "Good".  The
     toplevel menu may not look like

            Good
            Hell
            Heaven

     as now it isn't clear whether to visit the Good or the Heaven submenu.

     That rule allows usually for many different trees, and the task of the
     optimization procedure is to select, in a finite amount of time, the
     tree that best matches the user's desire about the optimum number of
     menu entries.


-------------------------------------------------------------------------------


8. Variables and functions in the install-menu scripts
------------------------------------------------------

     The supported "needs" definitions and "startmenu=", "endmenu=" and
     "submenutitle=" are interpreted as follows:


8.1. String constants
---------------------

     Anything inside double quotes ("") is interpreted as a string, and is
     written verbatim to the output file.  Escape sequences like \n, \t,
     ...  will be replaced with their C expansions (but currently \0xx
     octal escape sequences are not supported).


8.2. Variables
--------------

     Anything matching $[a-z,A-Z,_]* is interpreted as a variable, and the
     corresponding definition from the menu entry is substituted.

8.2.1. Special variables
------------------------

     The following variables are treated in a special way by install-menus,
     either because they are used for other purposes too, or because they
     are modified by install-menus (the ones marked with a "!"  are
     modified by install-menus).

     needs:
          Used to determine whether the window manager supports this menu
          entry.

     command:
          If this is undefined, this menu entry is taken as defining a
          sub-menu.  This way you can specify icons of sub-menus.

     title!:
          Used for sorting (see section).  For sub-menu entries (those with
          empty command), this is initialised to the last part of the
          section.  Please, keep the title short (two words at maximum).
          The title is for people who already know what program they want
          to start.  See "longtitle" and "description" below for longer
          descriptions.

     sort:
          Used for sorting (see section).  To make sure an entry is at the
          beginning, use something with a low ASCII number, like "$".  For
          sorting at the end, use "|"

     section!:
          Used to determine the section of the menu entry.  The menu
          entries that have a empty $command, ie those that define a
          submenu, have $title added to the end of $section The menu
          entries that have a non-empty $command have their $section
          modified to $section/$title, or $section/$sort:$title if $sort is
          defined.  The menu entries within one submenu are sorted
          according to $section.  If you want to retrieve the real section
          name, see the $basesection variable.

     basesection!:
          Used to contain the *real* section name.  This is useful because
          $section will be changed to $section/$title in special cases (see
          above).  This causes a problem when you want to do
          parent($section) because you won't get the real parent section.
          Instead you can use $basesection, which will never contain the
          title.

     hotkey!:
          Modified to reflect what install-menus thinks is the most
          suitable hotkey for this menu entry.  The hotkey= in the menu
          entry file is taken as a suggestion, that could be overwritten if
          there is another entry with the same hotkey=.  To suggest two
          possible hotkeys for an entry use hotkey="ab", with "a" being the
          most preferred hotkey.

8.2.2. Preferred variables
--------------------------

     The following aren't special for install-menus, but it's nice (read:
     essential) to use the same variables for the same things.  So, I'll
     suggest some here.  If you want to invent new ones, please do so and
     mail them to me so that I can include them here.

     icon:
          The location of the icon file for this menu entry.  If you don't
          have an icon file, just leave out the icon= in the menu entry.

     icon32x32:
          The location of a 32x32 icon file for this menu entry.

     icon16x16:
          The location of a 16x16 icon file for this menu entry.  This
          allows users to choose between 16x16 and 32x32 icon.

     longtitle:
          For people that like descriptive titles (about one line) It is
          probably best to include this in your menu entries, while the
          window-managers don't (by default) put it in the menus.  That
          way, people who want descriptive titles can turn them on, but
          others don't need to use them.

     description:
          An even longer description (about 5 lines).  For example, a
          description of the documentation in the dwww generated html
          pages.

8.2.3. Suggested variables
--------------------------

     The following variables probably shouldn't appear often (or at all) in
     the menu files supplied with packages.  They are mostly intended for
     use by local system managers.  Nevertheless, it is advised that all
     Debian systems use the following variable names:

     visible
          Some apps add entries to utmp the utmp file, so that "who" and
          friends know they are running (this is especially true for xterms
          etc).  If $visible set (to anything other than "" or "none"),
          xterms etc will not write logging info to utmp.  (may not work
          for your window manager).

     geometry
          For X apps, this will be the size of the (main) window that will
          be created (units in either chars or pixels, depending on type of
          main window (xterm or graphic)).  If you as package maintainer
          want to use this, you should probably think about setting this
          variable somewhere in an Xresources file.


8.3. Functions
--------------

     Anything matching `[a-zA-Z_]+' is taken as a function name, and an
     error is generated if the function doesn't exist.  The arguments of
     the functions can be other functions, string constants or variables.

     prefix()
          returns the current prefix dir: either $rootprefix, or
          $HOME/$userprefix, depending on who runs install-menu

     ifroot($rootarg, $userarg)
          if(getuid()==0) print $rootarg, else print $userarg

     print($arg)
          Same as just $arg; if $arg is empty, generate an error.

     nstring($n, $string)
          write $string $n times.  So, nstring(3,"Aa") writes "AaAaAa".
          (Useful in combination with level()).

     esc($arg1,$arg2)
          Print $arg1, but escape all occurrences of characters in $arg2
          with a '\' (thus, if arg1="hello", arg2="lo", print "he\l\l\o").

     escwith($arg1, $arg2, $arg3)
          Same as esc, but use $arg3 as escape sequence.

     escfirst($arg1, $arg2, $arg3)
          Same as escwith, but only escapes first occurrence of $arg2.

     cppesc($arg1)
          Escape anything that isn't a letter, number or _ with
          $<hex-ascii-code>.  So, for example, a '-' is replaced by '$2D'.
          This way, $arg1 can be used as a #define in cpp.

     tolower($arg)
     toupper($arg)
          Returns the argument set in lowercases resp uppercases.

     replacewith($s, $replace, $with)
          Search $s for occurrences of characters from string replace, and
          replace them by the corresponding character in $with.  Example:
          replacewith("hello $world, %dir", "$% ", "123") returns:
          "hello31world,32dir"

     replace($s, $replace, $with)
          Search $s for occurences of $replace and replace them with $with.
          Note that the behaviour of this function is quite different than
          the replacewith() function.

     ifempty($arg1, $arg2)
          If $arg1 is empty, print $arg2, otherwise print nothing.  For
          compatibility, $arg1="none" is interpreted as empty.

     ifnempty($arg1, $arg2)
          If $arg1 is not empty, print $arg2.  For compatibility, the
          string "none" is seen as empty.

     ifelse($arg1,$arg2,$arg3)
          If $arg1 is non-empty, print $arg2, otherwise $arg3.  For
          compatibility, the string "none" is seen as empty.

     ifeq($arg1, $arg2, $arg3)
          If ($arg1==$arg2) then print $arg3

     ifneq($arg1, $arg2, $arg3)
          If ($arg1!=$arg2) then print $arg3

     ifeqelse($arg1, $arg2, $arg3, $arg4)
          If ($arg1==$arg2) then print $arg3 else print $arg4

     cond_surr($arg1, $arg2, $arg3)
          If $arg1 is non-empty print $arg2$arg1$arg3, otherwise print
          nothing.  For compatibility, $arg1="none" is interpreted as
          empty.

     iffile($arg1, $arg2)
          If file $arg1 exists, and can be opened for reading by whoever
          started the current process, return $arg2, otherwise return
          nothing.

     ifelsefile($arg1, $arg2, $arg3)
          If file $arg1 exists, and can be opened for reading by whoever
          started the current process, return $arg2, otherwise return
          $arg3.

     catfile($arg1)
          Return the contents of file $arg1.

     shell($arg1)
          Return the output of the shell command $arg1.

     forall($array, "var", $exec)
          For each element of the column separated array $array, set $var
          to that element, and print $exec.  Example:

                     !include lang.h
                     forall(sections_translations(), "lang", \
                        " section[" $lang "]=" translate($lang, title()) "\n")

     parent($arg)
          for $arg a "directory", return parent directory:
          parent("/Debian/Applications/Editors") = "/Debian/Applications".

     basename($arg)
          return the last part of the parent directory:
          basename("/Debian/Applications/Editors") = "Applications".

     stripdir($arg)
          everything after the last slash, i.e.  what basename() should
          have returned: stripdir("/Debian/Applications/Editors") =
          "Editors".

     entrycount()
          the number of entries in this menu.

     entryindex()
          returns relative position of this entry.  Start with 0, last
          entry is entrycount() - 1.  BUG: if sort= anything other than
          $title, then this entryindex() will return incorrect values.

     firstentry($arg)
          return $arg if this is the first entry of this menu (that is,
          entryindex() = 0).  Else, return nothing.

     lastentry()
          return $arg if this is the last entry in this menu (that is,
          entryindex() = entrycount() -1).  Else, return nothing.

     level()
          return nesting of this menu in the total menu tree.

     add($arg1,$arg2)
     sub($arg1,$arg2)
     mult($arg1,$arg2)
     div($arg1,$arg2)
          returns the sum, difference, product or quotient of $arg1 and
          $arg2.  Note that the arguments are strings, that are converted
          to integers.  example: mult("24", entryindex())

     rcfile()
     examplercfile()
     mainmenutitle()
     rootsection()
     rootprefix()
     userprefix()
     treewalk()
     postoutput()
     preoutput()
          These functions all output whatever they were defined to be in
          the menu-method file.

     translate($lang, $text)
          Translate $text into $lang using gettext, see `forall' for an
          example.  Note that currently outputlanguage must be set to "C".
          If $lang is the empty string, $text will be translated in the
          current locale language.  See sections_translations() for a list
          of available translations.

     implicit concatenation
          String constants, variables and functions can be concatenated by
          placing them after each other with a space in between, like:
          "hello" ifelse($comma, $comma, " sorry" $period " comma not
          defined") " world"


-------------------------------------------------------------------------------


     Debian Menu System

     Joost Witteveen <joostje@debian.org>
     Joey Hess <joeyh@debian.org>
     Christian Schwarz <schwarz@debian.org>
     Bill Allombert <ballombe@debian.org>


     version 1.4, 31 May 2015

