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FVWMSCRIPT(1)							   FVWMSCRIPT(1)

NAME
     FvwmScript - module to build graphic user interface

SYNOPSIS
     FvwmScript must be spawned by Fvwm. It will not work from the command line.

DESCRIPTION
     FvwmScript  is  a	module which allows you to build many graphical applica-
     tions such as desktop accessories, button panel with pop  up  menus,  modal
     dialogs...  At the startup, FvwmScript reads the file which is specified on
     the command line. This file contains the script. This  script  is	not  in-
     cluded in the configuration file of Fvwm.

     An   FvwmScript  script  is  fully  controllable  by  using  the  keyboard.
     (Shift)-Tab circulates around the widgets, Return simulates a mouse  click,
     the  arrows  move	the cursor or change the values of the widget and Escape
     "cancels" for Menu and PopupMenu.

INVOCATION
     FvwmScript  can  be  invoked  by  inserting  the  line  `Module  FvwmScript
     name_of_script'  in  the .fvwm2rc file. The file "name_of_script" can start
     with a slash, in which case, it's a fully qualified path, and the	file  is
     read. If "name_of_script" does not start with a slash, FvwmScript will look
     in  a  few  different  places.  If  the .fvwm2rc contained the command line
     `*FvwmScript: Path path_of_the_script_directory', FvwmScript will try  that
     directory.  If that doesn't work, FvwmScript tries the system configuration
     directory and the user  configuration  directory  as  described  under  the
     "Read" command in the fvwm man page.

     The command to start FvwmScript can be placed on a line by itself, if Fvwm-
     Script  is to be spawned during fvwm's initialization, or can be bound to a
     menu or mouse button or keystroke to invoke it later.

CONFIGURATION OPTIONS
     The following commands can be used in the config file (see fvwm(1), section
     MODULE COMMANDS for details). They  are  used  only  if  the  corresponding
     script commands are not used in the script.

     *FvwmScript: DefaultFont font
	 Specifies  the default font to be used. If not specified with this com-
	 mand or in the script with the Font command, fixed font is assumed.

     *FvwmScript: DefaultFore color
	 Specifies the default foreground color to be  used.  If  not  specified
	 with this command or in the script with the ForeColor command, black is
	 used.

     *FvwmScript: DefaultBack color
	 Specifies  the  default  background  color to be used. If not specified
	 with this command or in the script with the BackColor	command,  grey85
	 is used.

     *FvwmScript: DefaultHilight color
	 Specifies  the  default hilight color to be used. If not specified with
	 this command or in the script with the HilightColor command, grey100 is
	 used.

     *FvwmScript: DefaultShadow color
	 Specifies the default shadow color to be used. If  not  specified  with
	 this  command	or in the script with the ShadowColor command, grey55 is
	 used.

     *FvwmScript: DefaultColorset colorset
	 Tells the module to use colorset colorset as the default colorset.

     *FvwmScript: DefaultCursor cursor
	 Tells the module to use X11 cursor cursor as the default for  all  wid-
	 gets.	Cursor	names  are those defined in the include file X11/cursor-
	 font.h but without XC_ prefix.

ANATOMY OF A SCRIPT
     FvwmScript uses a particular programming language. A script is composed  of
     five  parts. Heading contains general characteristics of the window and de-
     fault properties for all widgets. The  second  part  contains  instructions
     whom are executed at the startup of the script. The third part contains pe-
     riodic  tasks which are executed every second. The fourth part contains in-
     structions which are executed at exit. And the last part contains	the  de-
     scription	of widgets. A widget consists of eleven types of items: text la-
     bels, single-line text inputs, radio buttons, checkbox, push buttons, hori-
     zontal and vertical scrollbars, rectangles, pop up menus, swallowexecs  and
     mini scrollbars.

HEADING OF A SCRIPT
     The syntax is as follows:

     WindowTitle string
	 This option sets the window title.

     WindowSize width height
	 This option sets window size. width and height are numerical value.

     WindowPosition x y
	 This option sets window position. x and y are numerical value.

     ForeColor {color}
	 This option sets the default foreground color for all widgets.

     BackColor {color}
	 This option sets the default background color for all widgets.

     HilightColor {color}
	 This option sets the default hilight color for all widgets.

     ShadowColor {color}
	 This option sets the default shadow color for all widgets.

     Colorset {n}
	 This option sets the default colorset for all widgets.

     Font {font}
	 This option sets the default font for all widgets.

     UseGettext [locale_path]
	 Enable  the use of the gettext mechanism which is used by the WindowLo-
	 caleTitle, LocaleTitle, ChangeLocaleTitle instructions and the  Gettext
	 function.  If no argument is given, the default FvwmScript locale cata-
	 log is used. This catalog is under the locale fvwm installation  direc-
	 tory  and  the  text  domain  is  FvwmScript  (install_prefix/share/lo-
	 cale/*/LC_MESSAGES/FvwmScript.mo). You can reset this	catalog  or  add
	 some  catalogs  exactly  in  the same way than with the LocalePath fvwm
	 command (see the fvwm manual page). This instruction should  be  placed
	 before the WindowLocaleTitle instruction.

     WindowLocaleTitle string
	 This  option  sets  the window title, but use the locale catalog(s) de-
	 fined with UseGettext.

INITIALISATION
     This part contains instructions which will be executed at the startup.  For
     example:

	 Init
	 Begin
	   Do "Exec cat tada.voc > /dev/dsp" WarpPointer 1
	   Set $ToDo=Restart End

     These  instructions  are used to play a sound, move the pointer to widget 1
     and to initialize $ToDo to "Restart" at every startup.

PERIODIC TASKS
     This part of the script contains instructions that are executed every  sec-
     ond. For example:

	 PeriodicTasks
	 Begin
	   If (RemainderOfDiv (GetTime) 10)==0 Then
	     Do {Exec xcalc}
	   End

     This example shows how to launch xcalc every 10 seconds.

THE QUIT FUNCTION
     This  part  of  the script contains instructions that are executed when the
     script exits (after the Quit instruction or if you close  the  window  with
     the Close, Delete or Destroy fvwm command). For Example

	 QuitFunc
	   Begin
	     Do {Echo bye, bye}
	   End

     Be  aware that if you used the KillModule fvwm command to close the script,
     some instructions or functions which rely on the existence of a  communica-
     tion link between the script and fvwm will not be executed (for example the
     Do  command).  To	smoothly kill a script with an fvwm command see the COM-
     MANDS section.

MAIN OF A SCRIPT
     The second part of the script contains the description for every widget  in
     the script. Each widget description has two parts. The first part describes
     initial properties, the second part contains instructions that are executed
     when  the	widget	receives messages. All widgets can send and receive mes-
     sages. All messages are identified by a number. The message "UserAction" is
     sent to a widget when the user operates the  widget.  The	syntax	for  the
     first part is:

	 Widget 	id   # A number between 1 and 999 inclusive
	 Property
	  Type		string
	  Size width	height
	  Position	x y
	  Title 	{ string }
	  Value 	int
	  MaxValue	int
	  MinValue	int
	  Font		string
	  ForeColor	{ color }
	  BackColor	{ color }
	  HilightColor	{ color }
	  ShadowColor	{ color }
	  Colorset int
	  Flags 	flagsOpt

     The  flagsOpt  option  to Flags is a space separated list containing one or
     more of the keywords Hidden,  NoReliefString,  NoFocus,  Left  /  Center  /
     Right.  Hidden is used to specify if the widget is hidden at startup. NoRe-
     liefString specifies if strings are drawn with relief or not. NoFocus spec-
     ifies if the widget can get the keyboard focus or not. By default all  wid-
     gets  take  focus,  except Rectangle, HDipstick and VDipstick which cannot.
     Moreover, the NoFocus widgets are skipped when  you  circulate  around  the
     widgets with the (Shift-)Tab short cut. Left / Center / Right specifies the
     text  position.  These  apply  only  to ItemDraw, List, Menu, PopupMenu and
     PushButton. The default is Center for ItemDraw and PushButton and Left  for
     the other widgets.

     LocaleTitle  can be used in place of Title, for using the locale catalog(s)
     defined with UseGettext.

     The position of every widget must be specified.

     The syntax for the second part is:

	 Main
	 Case message of
	   SingleClic:
	   Begin
	    # list of instructions which will be
	    # executed when widget receives
	    # message "SingleClic". This message is
	    # generated by the user.
	   End
	   1 :
	    Begin
	     # list of instructions which will be
	     # executed when widget receives
	     # message 1
	    End
	 End

LIST OF WIDGETS
     There is fifteen types of widgets.

     CheckBox: Display check box with a string.
	 Title: title of the check box.

	 Value: if Value is equal to 1, the box is checked else it is not.

	 The Size property is ignored.

     HDipstick: Display a horizontal dipstick.
	 This widget can be used to display disk usage.

	 Value: specify the current value of the dipstick.

	 MinValue: specify the minimum value of the dipstick.

	 MaxValue: specify the maximum value of the dipstick.

	 A minimum size of 30x11 is imposed.

     HScrollBar: Display an horizontal scrollbar.
	 Value: position of the thumb.

	 MaxValue: upper limit of Value.

	 MinValue: lower limit of Value.

	 The height property is ignored and a  minimum	width  is  imposed.  The
	 width	should be at least the range plus 37 if all values are to be se-
	 lectable e.g. a min of 0 and max of 10 has a range of 11 and  therefore
	 should have a minimum width of 48.

     ItemDraw: Display an icon and/or a string.
	 Title: string to display.

	 Icon: icon to display.

	 MaxValue: x coordinate of the cursor.

	 MinValue: y coordinate of the cursor.

	 The size is made large enough to contain the title and/or the icon.

     List: Display a list.
	 List lets user to choose between various options.

	 Value: specify which option is selected.

	 MinValue: First visible option.

	 Title:  title contains options displayed in the list. The syntax is the
	 following: {Option 1|Option 2|...|Option N}. All menus are displayed at
	 the top of window.

	 A minimum height of three items is imposed and the width is made to  be
	 at least 108.

     Menu: Display a menu whom lets user to choose a option.
	 Items	of  type  Menu are layed out from left to right along the top of
	 the window. The size and position properties are ignored.

	 Value: specify which option is selected.

	 Title: title contains options displayed in the menu. The syntax is  the
	 following: {Option 1|Option 2|...|Option N}.

     MiniScroll: Display a very small vertical scrollbar.
	 Value: position of the thumb.

	 MaxValue: upper limit of Value.

	 MinValue: lower limit of Value.

	 The size is set to 19x34.

     PopupMenu: Display a pop up menu.
	 Value: specify what option is selected.

	 Title:  the  title has the following syntax: {Option 1|Option 2|...|Op-
	 tion N}."Option 1|Option 2|...|Option N" is the pop up  menu  which  is
	 displayed when pressing mouse button.

	 The size property is ignored.

     PushButton: Display push button with an icon and/or a string.
	 Title: this string has the following syntax {Title of the button|Option
	 1|Option  2|Option3|...|Option  N}. "Option 1|Option 2|...|Option N" is
	 the pop up menu which is displayed when pressing the right button.

	 Icon: icon to display.

	 The button is made large enough to fit the icon and or label.

     RadioButton: Display radio button with a string.
	 Title: title of the radio button.

	 Value: if Value is equal to 1, the box is checked else it is not.

	 The size property is ignored

     Rectangle: Display a rectangle.
	 This type of widget can be used to decorate window.

     SwallowExec
	 This type of widget causes FvwmScript to spawn an process, and  capture
	 the  first window whose name or resource is equal to Title, and display
	 it in the script window.

	 Title: specify the window name which be captured and displayed  in  the
	 script window.

	 SwallowExec:  specify the command line to execute to spawn the process.
	 Modules can also be swallowed.

	 Value: specify the looking of the border. Possible value: -1, 0, 1.

	 The size is made to be at least 30x30

     TextField: Display a text input field.
	 The text input field can be used to edit a single-line string.

	 Title: content of text field.

	 Value: position of the insert point.

	 MinValue: position of the end of the selection.

	 MaxValue: first visible character of the title

	 The height property is ignored, the width is made to  be  at  least  40
	 pixels wider than the initial contents.

     VDipstick: Display a vertical dipstick.
	 Value: specify the current value of the dipstick.

	 MinValue: specify the minimum value of the dipstick.

	 MaxValue: specify the maximum value of the dipstick.

	 The size is made to be at least 11x30.

     VScrollBar: Display a vertical scrollbar.
	 Value: position of the thumb.

	 MaxValue: upper limit of Value.

	 MinValue: lower limit of Value.

	 The  width  property  is  ignored  and a minimum height is imposed. The
	 height should be at least the range plus 37 if all values are to be se-
	 lectable e.g. a min of 0 and max of 10 has a range of 11 and  therefore
	 should have a minimum height of 48.

INSTRUCTIONS
     Here is the description of all instructions.

     HideWidget  id : hide the widget numbered id., ShowWidget id: show the wid-
     get numbered id., ChangeValue id1 id2
	 Set the value of the widget numbered id1 to id2.

     ChangeMaxValue id1 id2
	 Set the maximum value of the widget numbered id1 to id2.

     ChangeMinValue id1 id2
	 Set the minimum value of the widget numbered id1 to id2.

     ChangeTitle id1 id2
	 Set the title of the widget numbered id1 to id2.

     ChangeWindowTitle string
	 Set the title of the window to string.

     ChangeWindowTitleFromArg numarg
	 Set the title of the window to the value of the numarg-th script  argu-
	 ment.

     ChangeLocaleTitle id1 id2
	 As ChangeTitle but use the locale catalog(s) defined with UseGettext.

     ChangeIcon id1 id2
	 Set the icon of the widget numbered id1 to id2.

     ChangeForeColor id1 {color}
	 Set the foreground color of the widget numbered id1 to {color}.

     ChangeBackColor id1 {color}
	 Set the background color of the widget numbered id1 to {color}.

     ChangeColorSet id1 id2
	 Set the colorset of the widget numbered id1 to id2. Specifying widget 0
	 sets the main window colorset.

     ChangePosition id1 x y
	 Move the widget numbered id1 to position (x,y).

     ChangeSize id1 width height
	 Set the size of the widget numbered id1 to (width,height).

     ChangeFont id1 newfont
	 Set the font of the widget numbered id1 to newfont.

     WarpPointer id
	 Warp the mouse pointer into the widget numbered id.

     WriteToFile filename {str1} {str2} etc
	 Write to the file filename the string which is the concatenation of all
	 arguments str1, str2, etc.

     Do {command args}
	 Execute  the  fvwm command inside the Do block. Any fvwm command as de-
	 scribed in the fvwm man page can be used. Commands are sent  from  this
	 module  to the fvwm main program for processing. The length of the com-
	 mand and arguments can not exceed 988 characters.

     Set $var={str1} {str2} etc
	 Concatenate all arguments to a string and set the variable $var to this
	 string.

     Quit: quit the program., SendSignal id1 id2
	 Send a message numbered id2 to widget id1.

     SendToScript id_script {str11} {str2} etc
	 Send a message to the script identified by id_script.	The  message  is
	 the concatenation of str1, str2...

     Key Keyname Modifier id sig str1 str2 etc
	 Binds a keyboard key to the instruction

	 SendSignal id sig

	 and  sets  the "last string" to the concatenation of str1, str2... (see
	 the LastString function). The Keyname and Modifiers fields are  defined
	 as in the fvwm Key command.

ARGUMENTS
     Most  of  commands use arguments. There are two kinds of arguments: numbers
     and strings. A numerical argument is a value which is  between  -32000  and
     +32000.  A  string is always surrounded with braces. Variables always begin
     with the character "$" and can contain both numbers and strings.

FUNCTIONS
     All functions use arguments. Functions can return both a string and a  num-
     ber. The syntax is: (function argument1 argument2 etc)

     Here is the complete list of arguments:

     (GetTitle id)
	 Return the title of the widget numbered id.

     (GetValue id)
	 Return the current value of the widget numbered id.

     (GetMinValue id)
	 Return the current Min value of the widget numbered id.

     (GetMaxValue id)
	 Return the current Max value of the widget numbered id.

     (GetFore id)
	 Return  the  current  RGB foreground value of the widget numbered id in
	 the hex format RRGGBB.

     (GetBack id)
	 Return the current RGB background value of the widget	numbered  id  in
	 the hex format RRGGBB.

     (GetHilight id)
	 Return  the  current RGB hilight value of the widget numbered id in the
	 hex format RRGGBB.

     (GetShadow id)
	 Return the current RGB shadow value of the widget numbered  id  in  the
	 hex format RRGGBB.

     (GetOutput {str} int1 int2)
	 Executes the command str, gets the standard output and returns the word
	 which is in the line int1 and in the position int2. If int2 is equal to
	 -1, GetOutput returns the complete line.

     (NumToHex int)
	 Return the hexadecimal value of int.

     (HexToNum {str})
	 Return the decimal value of str, str must be an hexadecimal value.

     (Add int1 int2)
	 Return the result of (int1+int2).

     (Mult int1 int2)
	 Return the result of (int1*int2).

     (Div int1 int2)
	 Return the result of (int1/int2).

     (StrCopy {str} int1 int2)
	 Return  the string whom is between position int1 and int2. For example,
	 (StrCopy {Hello} 1 2) returns {He}

     (LaunchScript {str})
	 This function launches the script named str and returns an  identifica-
	 tion number. This number is necessary to use the functions SendToScript
	 and ReceiveFromScript. The string str contains the script name and some
	 arguments.

     (GetScriptArgument {int})
	 This  function returns the argument script used in the function Launch-
	 Script. If int is equal to zero, GetScriptArgument returns the name  of
	 the script.

     (GetScriptFather)
	 This function returns the identification number of the script father.

     (ReceivFromScript {int})
	 This function returns the message sent by the script numbered int.

     (RemainderOfDiv {int1 int2}): t
	 This function returns the remainder of the division (int1/int2).

     (GetTime)
	 This function returns the time in seconds.

     (GetPid)
	 This function returns the process id of the script.

     (Gettext {str})
	 This  function  return the translation of str by using the locale cata-
	 log(s) defined with UseGettext.

     (SendMsgAndGet {comId} {cmd} bool)
	 Sends the command cmd with identifier	comId  to  an  external  program
	 ready to communicate with the script using a protocol specific to Fvwm-
	 Script.  If  bool  is 0 FvwmScript does not wait for an answer from the
	 external program. In this case the returned value is 1 if  the  message
	 can  be  sent to the external program and 0 if this is not the case. If
	 bool is 1, then FvwmScript waits for an answer from the  external  pro-
	 gram  and the return value is this answer (a line of no more than 32000
	 characters). If the communication fails, the returned value is  0.  See
	 the  section A COMMUNICATION PROTOCOL for a description of the communi-
	 cation protocol used.

     (Parse {str} int)
	 where str must be a string of the form: X1S1X2S2X3S3...SnXn

	 where the Xn are numbers containing four decimal digits  and  where  Sn
	 are  strings  of  length  exactly  Xn. The returned value is the string
	 Sint. If int is out of range (e.g., >n) the returned value is the empty
	 string. If str is not of the specified form, the return value is unpre-
	 dictable (but empty in the average). This function is useful to  handle
	 strings returned by the SendMsgAndGet function.

     (LastString)
	 This function returns the "current working string" for the Key instruc-
	 tion  and the SendString command (see the COMMANDS section). At startup
	 this string is empty, but when a Key binding is detected (respectively,
	 a SendString command is received), then  this	string	is  set  to  the
	 string associated to the instruction (respectively, to the command).

CONDITIONAL LOOPS
     There  are three kinds of conditional loops. The instruction "If-Then-Else"
     has the following syntax:

	 If $ToDo=={Open xcalc} Then
	   Do {Exec xcalc &}		     # List of instructions
	   Else
	   Begin
	     Do {Exec killall xcalc &}	       # List of instructions
	     Do {Exec echo xcalc killed >/dev/console}
	   End

     The second part "Else-Begin-End" is optional. If the loop contains only one
     instruction, Begin and End can be omitted. The instruction  "While-Do"  has
     the following syntax:

	 While $i<5 Do
	 Begin
	   Set $i=(Add i 1)		    # List of instructions
	 End

     Two  strings can be compared with "==" and two numbers can be compared with
     "<", "<=", "==", ">=", ">". The loop "For-Do-Begin-End" has  the  following
     syntax:

	 For $i=1 To 20 Do
	 Begin
	   Do {Exec xcalc &}		     # List of instructions
	 End

COMMANDS
     The following fvwm command may be executed at any time

	 SendToModule ScriptName SendString id sig str

     it  sends	to  any  module  with alias or name which matches ScriptName the
     string

	 SendString id sig str

     When an FvwmScript receives such a message it sends to the  Widget  id  the
     signal  numbered sig and the string str can be obtained with the LastString
     function. Let us give an example. Say that you have a script MyScript  with
     the widget:

	 Widget 50
	 Property
	   Type PushButton
	   Title {Quit}
	   ...
	 Main
	 Case message of
	   SingleClic:
	      Begin
		Quit
	   End

	   1 :
	   Begin
	     Set $str = (LastString)
	     If $str == {Quit} Then
	       Quit
	     Else
	       ChangeTitle 33 $str
	   End
	 End

     Then the command

	 SendToModule MyScript SendString 50 1 str

     forces MyScript to exit if str is equal to "Quit" and if not it changes the
     title of Widget 33 to str.

     This command can be used to change the window title

	 SendToModule ScriptName ChangeWindowTitle newTitle [oldTitle]

     it  causes  that  any  module  with  alias or name which matches ScriptName
     changes its associated window title  to  newTitle.  The  optional	argument
     oldTitle  makes  sense when there are several instances of the same script.
     It permits one to avoid changing the name of all these instances by  speci-
     fying the name of the window associated to the target script (see the exam-
     ple below).

	 + I Module FvwmScript FvwmStorageSend "/dev/hda6"
	 + I Wait FvwmStorageSend
	 + I SendToModule FvwmStorageSend ChangeWindowTitle HDA6
	 + I Module FvwmScript FvwmStorageSend "/dev/hda1"
	 + I Wait FvwmStorageSend
	 + I SendToModule FvwmStorageSend ChangeWindowTitle HDA1 FvwmStorageSend

     Without  the  FvwmStorageSend  argument  in the last case, the SendToModule
     command would have changed to HDA1 the name of both instances of  FvwmStor-
     ageSend.

EXAMPLES
     You will find examples of scripts in the fvwm configuration directory.

     FvwmScript-BellSetup, FvwmScript-KeyboardSetup, FvwmScript-PointerSetup and
     FvwmScript-ScreenSetup  are  a set of scripts that modify X settings. These
     scripts save preferences into a file named ~/.xinit-fvwmrc (If you want  to
     use another file name, give it as the first argument of the script). If you
     want  to  load  these preferences at every startup, you have to include the
     line ".xinit-fvwmrc" in your .xinitrc (or .xsession) file	before	starting
     fvwm.

     FvwmScript-BaseConfig  modifies  fvwm focus and paging mouse policy, window
     placement, opacity and other features of the move and resize commands, snap
     attraction and shading animation. This script saves preferences into a file
     named .FvwmBaseConfig in the user's data directory  (i.e.,  $HOME/.fvwm  or
     $FVWM_USERDIR  if	set).  If  you	want  to load these preferences at every
     startup you must add the line "Read .FvwmBaseConfig" in your fvwm	configu-
     ration file. If you want to use another file name, give it as the first ar-
     gument  of  the script. When you click on Ok or Apply an fvwm function that
     you may define named BaseConfigOkFunc  or	BaseConfigApplyFunc  is  called.
     This  allows  for reloading specific application styles that the script has
     destroyed (e.g., AddToFunc BaseConfigOkFunc I Read MyAppStyle).

     FvwmScript-Buttons is a buttons panel which can replace  FvwmButtons  (this
     script supports popup menus and requires xload, xclock, FvwmPager, TkDesk).
     FvwmScript-Colorset  allows  you to edit your colorset. FvwmScript-Date al-
     lows you to set date and time. FvwmScript-FileBrowser  is	a  file  browser
     used  by  the  other scripts. FvwmScript-Find is an elementary front-end to
     find. FvwmScript-Quit allows one to quit fvwm, restart fvwm or  some  other
     window manager, or shut down and reboot the computer. FvwmScript-ScreenDump
     is a screen dumper. FvwmScript-WidgetDemo is a pure example script. See the
     next section for FvwmScript-ComExample.

A COMMUNICATION PROTOCOL
     FvwmScript is a weak (but simple) programming language. If you need to deal
     with a lot of data and/or you need to use complex algorithms you should use
     an  external  program (in perl for example) and "send" the desired informa-
     tion to your FvwmScript script. The first approach is to use the  GetOutput
     function.	This  is  simple but you should rerun your external program each
     time you need information from it (and this may  cause  performances  prob-
     lems).  The  second approach is to use the SendMsgAndGet function which ex-
     tends FvwmScript by using any programming	language  which  can  deal  with
     named  pipes  (fifos).  We describe this solution in this section. (A third
     approach is to use fvwm-themes-com from the  fvwm-themes  package,  but  in
     fact  the	SendMsgAndGet method is an implementation of fvwm-themes-com in-
     side FvwmScript and this gives better performance).

     Basically, you start an "external" program (the  program  for  short)  from
     your  FvwmScript  script  (the  script for short). This program runs in the
     background and you use the SendMsgAndGet function in  your  script  to  ask
     questions or to give instructions to the program. The program must strictly
     respect  a certain communication protocol. First of all there is an identi-
     fier comId for the communication, it should contain the process id  of  the
     script  for  a good implementation of the protocol (use the GetPid function
     and pass the comId via an option to the program). The protocol uses two fi-
     fos,  in  the   fvwm   user   directory,	named:	 .tmp-com-in-comId   and
     .tmp-com-out-comId.   The	 program   should   create  and  listen  on  the
     .tmp-com-in-comId fifo. Then, when FvwmScript executes a  function  of  the
     form:

	 Set $answer = (SendMsgAndGet {comId} {cmd} bool)

     FvwmScript  writes  the cmd on this fifo. This way the program can read the
     cmd and can execute the appropriate action (it should remove the in fifo to
     support multi-communications). If bool is 0, FvwmScript does not  wait  for
     an answer from the program and return 1 if the previous actions succeed and
     0	if  they  failed  (then the program should "go back" to the in fifo). If
     bool is 1, then FvwmScript waits (20 sec) for an answer  from  the  program
     and  in turn returns the answer to the script (note that bool is not passed
     to the program as it must know which commands need an answer).  To  answer,
     the  program  creates  the .tmp-com-out-comId fifo and writes the answer on
     it. The program should wait until FvwmScript reads the answer and	then  it
     should  remove  the  out fifo and go back to the in fifo. The answer should
     consist of one line of no more than 32000 characters (take a  look  at  the
     Parse function to handle multiple lines as one line).

     A	simple way to understand this protocol and to write scripts and programs
     that use it is to take a look at the (not useful) example FvwmScript-ComEx-
     ample and fvwm-script-ComExample.pl (that can found in the fvwm data direc-
     tory). Moreover, this implementation of the protocol solves  questions  as:
     What  to do if the script exits for a bad reason? What to do if the program
     exits for a bad reason? ...etc.

BUGS
     FvwmScript crashes if widgets are accessed that have not been defined.

AUTHOR
     Frederic Cordier (cordie97@cui.unige.ch or f-cord96@univ-lyon1.fr).

CONTRIBUTOR
     Eddy J. Gurney (eddy@gizmo.aa.ans.net).

				   2026-06-27			   FVWMSCRIPT(1)

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