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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<title>Fvwm Configuration in Different Environments using cpp Issue 21</title>
</HEAD>
<BODY BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#0020F0"
ALINK="#FF0000">
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<H4>
"Linux Gazette...<I>making Linux just a little more fun!</I>"
</H4>
<P> <HR> <P>
<!--===================================================================-->
<center>
<H2>Fvwm Configuration in Different Environments using cpp</H2>
<H4>By Gerd Bavendiek,
<a href="mailto:bav@rw.sni.de">bav@rw.sni.de</a></H4>
</center>
<P><HR><P>
<h1>Do you use Linux at home ? In the office ? On a laptop ?
Do you use fvwm 2.xx or fvwm95 as your windowmanager ?</h1>
If yes, you should read on.
<p>
Perhaps you have read my article about <a
href="../issue20/laptop.html">Using a
Laptop in Different Environments</a>. There I described an
easy way to setup a Linux laptop to boot into different
network configurations. I mentioned that setting up a shell
variable called <code>PROFILE</code> is useful not only for
configuring the network but also the windowmanager.
<h2>Why should you do that ?</h2>
Your windowmanager needs to be configured quite different when you are
using it on a laptop with 600x420 pixel or on a 17"-monitor with
1024x768 pixel. This is a rather basic difference - there may be
others. Think of using your system in a network environment. There it
will be handy to have a taskbar labeled appropiate to <code>rlogin</code>-sessions.
After fiddling some time with patching different
fvwm configuration files on different machines I found this to be a
pain. A typical <code>.fvwm95rc</code> is about 900 lines. Keeping several of them
in sync is not the thing I like.
<h2>Generating ~/.fvwm95rc using cpp</h2>
My solution is simple: Use <code>cpp</code>, the C-preprocessor ! fvwm 2.xx as well
as fvwm95 are configured by a central file. fvwm95 is derived from
fvwm, so the basic idea applies to both. Let me show you the details
using fvwm95. I keep my fvwm95 configuration in the file <code>~/.fvwm95rc-cpp</code>.
<p>
You can use the system default setup in
<code>/etc/X11/fvwm95/system.fvwm2rc95</code> as starting point.
Look at this code fragment from my <code>.xinitrc</code> (For me, <code>.xsession</code> is
linked to <code>.xinitrc</code>):
<pre>
...
# I need the value of PROFILE for generating .fvwm95rc
# netenv contains an assignment like e.g. PROFILE=32
if [ -r /tmp/netenv ]; then
. /tmp/netenv
fi
# Now the actual .fvwm95rc is generated depending on the value of PROFILE
cpp -lang-c++ -D PROFILE=$PROFILE ~/.fvwm95rc-cpp ~/.fvwm95rc
exec fvwm95 # exec saves the extra memory for a no longer useful shell ...
...
</pre>
The shell variable <code>PROFILE</code> contains the information about the current
environment. The file <code>/tmp/netenv</code> is set up by <code>init</code> when going to run
level 2. I described this in the article mentioned above.
Obviously you need <code>cpp</code>, which comes either as an extra package or as
part of <code>gcc</code>. Yes, I know that there is a module <code>FvwmCpp</code> (which calls
<code>cpp</code>) - but I never managed to get it work.
<p>
One advantage of the old-fashioned style of configuration files is
that you can put comments in. <i>You really should do this !</i> All that
hidden dot files in your home directory make up your personal
environment (these files will never be touched by a system
update). Having comments will make it easier to maintain this
environment.<p>
<code>system.fvwm95rc</code> comes in shell style comment syntax (so does
fvwm). You can't feed this into <code>cpp</code>. I didn't like
traditional c-style comments in a configuration file, so I switched
all these comment lines
<pre>
# this is a useful comment
</pre>
into c++-style comments
<pre>
// this is a useful comment
</pre>
(hail emacs !). Calling <code>cpp</code> with
<pre>
-lang-c++
</pre>
tells <code>cpp</code> to preprocess c++-code. A hint for those, who are not
familiar with <code>cpp</code>: <code>cpp</code> strips off the comment lines of the input
file. You probably will get output with a lot of blank lines.
<h2>Examples how to use cpp-syntax</h2>
Now let us have a look inside my <a href="../issue21/fvwm95rc-cpp.html"><code>.fvwm95rc-cpp</code></a>.
Of course, everything herein is strongly a matter of personal taste.
<p>
I don't like to stress my eyes. So I hate small letters, I barely can
read them in the evening of a long day ... So my desktop has 4x2 pages.
Each page is assigned to one application (or a few). I use
<code><Alt><F1></code> to <code><F8></code> to
switch quickly between pages. Using the fabulous fvwm95 mini icons my
screen holds the <code>FvwmTaskBar</code> and on the right hand side a column
holding some icons. This way I can maximize the application window.
<p>
The <a href="./gx/fvwm/page-1.gif">screenshot</a> should make it clear.
<h3>Defining geometry</h3>
One important application is xemacs for me. So I define a mini button
in the <code>FvwmButtons</code> section like this:
<pre>
*MiniButtons - mini-edit.xpm Exec "Xemacs" /usr/bin/xemacs \
-geometry EMACS_GEO &
</pre>
<code>EMACS_GEO</code> is to be substituted by
<code>cpp</code>. I put all the <code>#define</code> in the
beginning of my <code>.fvwm95rc-cpp</code>. Basically it reads like this
<pre>
#if PROFILE == 30 || PROFILE == 31 || PROFILE == 32
#define EMACS_GEO 80x25+0+480
#else
#define EMACS_GEO 96x31+0+767
#endif
</pre>
Whenever I'm on my laptop, <code>PROFILE</code> equals 30, 31
oder 32 (at home, in the office, on customers site). The
LCD-Display has 600x420 pixel. My other systems have 17" monitors and
there I use 1024x768. The +0+480 or +0+767 pops up the xemacs window
on the leftmost page on the bottom row of my 4x2 desktop. But this is
true only when being on the very first page while clicking the
icon. I'm shure, this could be improved.
<p>
With defining
<pre>
Key F5 A M GotoPage 0 1
</pre>
I can conveniently switch to my xemacs window using <code><ALT><F5></code> without
leaving the keyboard.
<h3>Launching applications</h3>
Being at home or in the office, I have usually some <code>rlogin</code> sessions to
some well known machines. Being on a customers site I frequently have
to work with high availability configurations mostly consisting of two
machines. I call them always abba and bebe. See how this can be set
up (shortened for clarity):
<pre>
DestroyFunc "InitFunction"
#if PROFILE == 30
AddToFunc "InitFunction" \
"I" Exec xsetroot -solid turquoise4 -cursor_name top_left_arrow &
+ "I" Exec xconsole -font 6x10 -geometry XCONSOLE_GEO -sb -file /dev/xconsole &
+ "I" Exec rxvt -geometry 94x28+0+0 -fn DEF_FONT -ls -sb -vb \
-title TERMWIN_ID1 -n TERMWIN_ID1 -cr Yellow3 &
+ "I" Exec rxvt -geometry TERMWIN_GEO2 -fn DEF_FONT -ls -sb -vb \
-title TERMWIN_ID2 -n TERMWIN_ID2 -cr Red3 &
+ "I" Exec rxvt -geometry TERMWIN_GEO3 -fn DEF_FONT -ls -sb -vb \
-title TERMWIN_ID3 -n TERMWIN_ID3 -cr Magenta3 &
+ "I" Module FvwmButtons MiniButtons
+ "I" Module FvwmTaskBar
+ "I" Module FvwmAuto 700
+ "I" Module FvwmPager 0 0
#elif PROFILE == 10
...
#else
AddToFunc "InitFunction" \
...
...
+ "I" Exec rxvt -geometry 94x28+0+0 -fn DEF_FONT -ls -sb -vb \
-title TERMWIN_ID1 -n home -cr Yellow3 &
+ "I" Exec rxvt -geometry TERMWIN_GEO2 -fn DEF_FONT -ls -sb -vb \
-title TERMWIN_ID2 -n TERMWIN_ID2 -cr Red3 &
+ "I" Exec rxvt -geometry TERMWIN_GEO3 -fn DEF_FONT -ls -sb -vb \
-title TERMWIN_ID3 -n TERMWIN_ID3 -cr Magenta3 &
+ "I" Exec rxvt -geometry TERMWIN_GEO4 -fn DEF_FONT -ls -sb -vb \
-title TERMWIN_ID4 -n TERMWIN_ID4 -cr Green3 &
+ "I" Exec rxvt -geometry TERMWIN_GEO5 -fn DEF_FONT -ls -sb -vb \
-title TERMWIN_ID5 -n TERMWIN_ID5 -cr Blue3 &
...
...
#endif
</pre>
<p>
The terminal geometry und identifiers are defined as follows:
<p>
<pre>
#if PROFILE == 10
#define TERMWIN_ID1 bav@nana
#define TERMWIN_ID2 nana
#define TERMWIN_ID3 lulu
#elif PROFILE == 20
...
#elif PROFILE == 30
...#define TERMWIN_ID1 bav@lulu
#elif PROFILE == 31
...
#elif PROFILE == 32
#define TERMWIN_ID1 bav@lulu
#define TERMWIN_ID2 lulu
#define TERMWIN_ID3 abba
#define TERMWIN_ID4 bebe
#define TERMWIN_ID5 abba
#endif
</pre>
<h2>Conclusion</h2>
Screen geometry and network environment differ from one machine to
another. Everyone, who wants to have <b>one</b>
configuration file for his fvwm 2.xx or fvwm95 to reflect these
differences, should consider to use <code>cpp</code> as shown.
<p>
Perhaps you know, that <code>xrdb(1)</code> also can
make use of <code>cpp</code>. So
you can preprocess your <code>~/.Xdefaults</code> achieving the discussed advantages.
<p>
I hope you will find these ideas somehow useful !
<p>
Kind regards
<p>
Gerd
<hr>
<address><a href="mailto:bav@rw.sni.de">Gerd Bavendiek</a></address>
<!--===================================================================-->
<P> <hr> <P>
<center><H5>Copyright © 1997, Gerd Bavendiek<BR>
Published in Issue 21 of the Linux Gazette, September 1997</H5></center>
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