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<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
<html> <head>
<title>Miscellaneous Notes</title>
</head>
<body bgcolor="#ffefd5" text="#181871">
<H4>
"Linux Gazette...<I>making Linux just a little more fun!</I>
"</H4>
<P> <HR> <P>
<!--===================================================================-->
<center><h1>Miscellaneous Notes</h1></center>
<center><h4><a href="mailto: layers@vax2.rainis.net">by Larry
Ayers</a></h4></center>
<center>Copyright (c) 1996</center><BR>
<center><H5>Published in Issue 13 of the Linux Gazette</H5></center>
<hr>
<center><h3>Fun with Little Shell-Scripts</h3></center>
<p>After typing the same command or editing the same rc-file for
the dozenth time the idea of a short executable shell-script
will gradually rise to the surface of my mind. As an example,
last year after much trial-and error I figured out how to start
my S3 X-server in 16-bit mode. This was great, but I found that
there were a few programs which preferred to be run in 8-bit
mode. Typing <i>startx -- -bpp 16</i> and <i>startx -- -bpp 8</i>
began to become tiresome; then it dawned on me that I could
write a shell script for each color-depth which would do the
typing for me. One of them looks like this:<br><pre>
#!/bin/sh
# x16: starts x in 16-bit mode
startx -- -bpp 16
</pre>
<p>Just a simple little script (made executable with
<i>chmod +x x16</i>) but so handy!
<p>Encouraged by this, it occurred to me that changing
window-managers could be done in a similar way. I normally use
fvwm2, but lately I've been fooling around with one of fvwm's
hacked offspring, the Afterstep window-manager. Since I didn't
have Afterstep's configuration quite as usefully customised as
my mainstay fvwm2's, I didn't want to use it the majority of the
time. Rather than editing ~/.xinitrc each time I wanted to
switch to Afterstep, then again to switch back, I copied
~/.xinitrc twice. The first copy is .xinitrc-f and it's just my
normal copy. The second, .xinitrc-a starts Afterstep instead.
The scripts which control this are as follows:<br><pre>
#!/bin/sh
# xa: starts x with afterstep
cp ~/.xinitrc-a ~/.xinitrc ; startx
</pre>
<p>and<br><pre>
#!/bin/sh
# xf: starts x with fvwm2
cp ~/.xinitrc-f ~/.xinitrc ; startx
</pre>
<p>Of course, while in an X-session another window-manager can be
easily started from a menu. I spend a fair amount of time
working in a console session without X running, in which case
the above scripts are useful.
<p>It just occurred to me as I write this that these tasks could
be as easily done using aliases or functions in ~/.bashrc. The
only difference I suppose would be that shell-functions are
memory-resident whereas the scripts aren't.
<p>These examples may seem self-evident or trivial to the
unix-gurus out there, but they were part of the learning process
for me. Perhaps this piece will encourage the beginners out
there to try some similar scripting.
<hr>
<center><h3>Keyboards and RXVT</h3></center>
<p> Here's a discovery I made recently concerning rxvt, the
memory-saving alternative to xterm. I received an email message
recently in response to my article last month concerning S-lang
applications, in which I opinionated about rxvt vs. xterm. The
poster of the message wondered whether there is any way to use
shift-page-up and shift-page-down to scroll the rxvt window,
similar to the way console screens (and xterms) scroll. I had
tried to get this to work without success, and some usenet
messages had led me to believe that without patching the source
rxvt just wouldn't scroll from the keyboard.
<p>Recently I installed the S.u.S.E. distribution, but didn't
install the supplied rxvt package. I recompiled rxvt version
2.19 in this new environment, and to my surprise the
above-mentioned scrolling keys worked! This piqued my
curiosity, so I began prowling through the directory hierarchy
searching for the difference in config files which made this
behaviour possible. I came up with two differences: first,
there was a new entry in the ~/.Xmodmap file. The lines<br><pre>
keycode 64 = Meta_L
keycode 0x6D = Multi_key
</pre>
<p>had been added to the "keycode 22 = BackSpace" line which I had
in my previous installation. Second, the /etc/termcap file was
different than the ones I'd seen before; a new rxvt stanza had
been included which looks like this:<br><pre>
rxvt|rxvt terminal emulator:\
:am:km:mi:ms:xn:xo:\
:co#80:it#8:li#65:\
:AL=\E[%dL:DC=\E[%dP:DL=\E[%dM:DO=\E[%dB:IC=\E[%d@:\
:LE=\E[%dD:RI=\E[%dC:UP=\E[%dA:ae=^O:al=\E[L:as=^N:bl=^G:\
:cd=\E[J:ce=\E[K:cl=\E[H\E[2J:cm=\E[%i%d;%dH:cr=^M:\
:cs=\E[%i%d;%dr:ct=\E[3k:dc=\E[P:dl=\E[M:do=^J:ei=\E[4l:\
:ho=\E[H:ic=\E[@:im=\E[4h:\
:is=\E[r\E[m\E[2J\E[H\E[?7h\E[?1;3;4;6l\E[4l:\
:k1=\E[11~:k2=\E[12~:k3=\E[13~:k4=\E[14~:k5=\E[15~:\
:k6=\E[17~:k7=\E[18~:k8=\E[19~:k9=\E[20~:kI=\E[2~:\
:kN=\E[6~:kP=\E[5~:kb=\177:kd=\EOB:ke=\E[?1l\E>:kh=\E[H:\
:kl=\EOD:kr=\EOC:ks=\E[?1h\E=:ku=\EOA:le=^H:md=\E[1m:\
:me=\E[m:mr=\E[7m:nd=\E[C:rc=\E8:sc=\E7:se=\E[m:sf=^J:\
:so=\E[7m:sr=\EM:ta=^I:te=\E[2J\E[?47l\E8:ti=\E7\E[?47h:\
:ue=\E[m:up=\E[A:us=\E[4m:
</pre>
<p>I have noticed, though, that if I type the command
<i>echo $TERM</i> in an rxvt window the result is <i>xterm-color</i>, so
perhaps the above rxvt termcap entry isn't being used at all.
<p>I'd love to know if anyone else has any luck transplanting
either or both of these two changes into their system. The rxvt
termcap entry can be pasted right into your /etc/termcap file; in
mine it is right after the xterm stanzas. I don't believe the
order of stanzas is important, though.
<hr>
<center><h3>Partitions and Directories</h3></center>
<p>After using linux for a while you tend to take for granted the
supple flexibility inherent in the Linux manner of dealing with
files, partitions, and mount-points. Recently I began to feel
constrained by a relatively small /usr partition, so I thought
I'd do some experimenting.
<p>I happened to have an unused 100 mb. partition on my disk, so
I created an ext-2 filesystem on it and mounted it on an empty
directory, /new, created for this purpose. Then I ran this
command: cp -a /usr/X11R6 /new. Using cp with the -a switch is
really handy, as it copies all subdirectories, links, and files,
and also saves permissions.
<p>The next step was modifying the /etc/fstab file, inserting the
following entry which causes /usr/X11R6 to be mounted on the new
partition:<br><pre>
/dev/hda11 /usr/X11R6 ext2 defaults 1 2
</pre>
<p>Before rebooting I dropped back to a console and deleted the
entire contents of the /usr/X11R6 directory.
<p>I was reasonably certain this would work, but I must confess I
was surprised when (after rebooting) X started up without
comment, as if nothing had changed.
<p>Linux doesn't really care, after all, where files are located,
as long as there is a congruence between the partition table and
the contents of the /etc/fstab file. One benefit of this laxity
is that repartitioning (with all of the attendant backing up,
restoring, etc.) should seldom be necessary.
<hr>
<p><address><a href="http://vax2.rainis.net/~layers/">Larry Ayers<layers@vax2.rainis.net></a></address>
<!-- hhmts start -->
Last modified: Tue Dec 17 21:31:27 CST 1996
<!-- hhmts end -->
<P> <hr> <P>
<center><H5>Copyright © 1997, Larry Ayers <BR>
Published in Issue 13 of the Linux Gazette</H5></center>
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