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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<html>
<head>
<title>More 2 Cent Tips & Tricks Issue 13</title>
</head>
<BODY BGCOLOR=#C0C0C0 TEXT=#000000 LINK=#0000FF VLINK=#0020F0
ALINK=#FF0000 BACKGROUND="../gx/spirbind.gif">
<table width=100%>
<tr><td><img src="../gx/blank.gif" width=50></td>
<td>
<H4>&quot;Linux Gazette...<I>making Linux just a little more fun!</I>
&quot;</H4>
<P> <hr> <P>
<!-- QUICK TIPS SECTION ================================================== -->
<center>
<H1><A NAME="tips"><IMG ALIGN=MIDDLE ALT="" SRC="../gx/twocent.gif">
More 2&#162; Tips!</A></H1> <BR>
Send Linux Tips and Tricks to <A HREF="mailto:gazette@ssc.com">
gazette@ssc.com
</A></center>
<p><hr><p>
<H3>Contents:</H3>
<ul>
<li><a HREF="./lg_tips13.html#free">Another 2cent Tip for LG</a>
<li><a HREF="./lg_tips13.html#console">Console Trick Follow-up</a>
<li><a HREF="./lg_tips13.html#gif">GIF Animations</a>
<li><a HREF="./lg_tips13.html#adm">How to close and reopen a new /var/adm/messages file</a>
<li><a HREF="./lg_tips13.html#admin">How to truncate /var/adm/messages</a>
<li><a HREF="./lg_tips13.html#infozip">Info-ZIP encryption code</a>
<li><a HREF="./lg_tips13.html#kernel">Kernel Compile Woes</a>
<li><a HREF="./lg_tips13.html#title">Letter 1 to LJ Editor re Titlebar</a>
<li><a HREF="./lg_tips13.html#more">Letter 2 to LJ Editor re Titlebar</a>
<li><a HREF="./lg_tips13.html#redial">PPP redialer script--A Quick Hack </a>
<li><a HREF="./lg_tips13.html#table">TABLE tags in HTML</a>
<li><a HREF="./lg_tips13.html#undelete">Text File undelete</a>
<li><a HREF="./lg_tips13.html#var">Truncating /var/adm/messages</a>
<li><a HREF="./lg_tips13.html#host">2c Host Trick</a>
<li><a HREF="./lg_tips13.html#tcsh">Use of TCSH's :e and :r Extensions</a>
<li><a HREF="./lg_tips13.html#notes">Various notes on 2c tips, Gazette 12</a>
<li><a HREF="./lg_tips13.html#howto">Viewing HOWTO Documents</a>
<li><a HREF="./lg_tips13.html#xaw">Xaw-XPM .Xresources troubleshooting tip</a>
<li><a HREF="./lg_tips13.html#xterm">Xterm Titlebar</a>
</ul>
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="free"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
Another 2cent Script for LG
</H3>
Date: Wed, 11 Dec 1996 23:34:58 +0100 <BR>
From: Hans Zoebelein, <A HREF="mailto:zocki@goldfish.cube.net">
zocki@goldfish.cube.net</A><BR>
<P>
Hello LG people,
<P>
here comes a short script which will check from time to time
that there is enough free space available on anything
which shows up in mount (disks, cdrom, floppy...)
<P>
If space runs out, a message is printed every X seconds
to the screen and 1 mail message per filled device is fired up.
<P>
Enjoy! <BR>
Hans
<PRE>
#!/bin/sh
#
# $Id: lg_tips13.html,v 1.3 2003/02/03 21:50:18 lg Exp $
#
#
# Since I got mysterious error messages during compile when
# tmp files filled up my disks, I wrote this to get a warning
# before disks are full.
#
# If this stuff saved your servers from exploding,
# send praising email to zocki@goldfish.cube.net.
# If your site burns down because of this, sorry but I
# warned you: no comps.
# If you really know how to handle sed, please forgive me :)
#
#
# Shoot and forget: Put 'check_hdspace &' in rc.local.
# Checks for free space on devices every $SLEEPTIME sec.
# You even might check your floppies or tape drives. :)
# If free space is below $MINFREE (kb), it will echo a warning
# and send one mail for each triggering device to $MAIL_TO_ME.
# If there is more free space than trigger limit again,
# mail action is also armed again.
#
# TODO: Different $MINFREE for each device.
# Free /*tmp dirs securely from old junk stuff if no more free space.
DEVICES='/dev/sda2 /dev/sda8 /dev/sda9' # device; your put disks here
MINFREE=20480 # kb; below this do warning
SLEEPTIME=10 # sec; sleep between checks
MAIL_TO_ME='root@localhost' # fool; to whom mail warning
# ------- no changes needed below this line (hopefully :) -------
MINMB=0
ISFREE=0
MAILED=""
let MINMB=$MINFREE/1024 # yep, we are strict :)
while [ 1 ]; do
DF="`/bin/df`"
for DEVICE in $DEVICES ; do
ISFREE=`echo $DF | sed s#.\*$DEVICE" "\*[0-9]\*" "\*[0-9]\*" "\*## | sed s#" ".\*##`
if [ $ISFREE -le $MINFREE ] ; then
let ISMB=$ISFREE/1024
echo "WARNING: $DEVICE only $ISMB mb free." >&2
#echo "more stuff here" >&2
echo -e "\a\a\a\a"
if [ -z "`echo $MAILED | grep -w $DEVICE`" ] ; then
echo "WARNING: $DEVICE only $ISMB mb free.
(Trigger is set to $MINMB mb)" \
| mail -s "WARNING: $DEVICE only $ISMB mb free!" $MAIL_TO_ME
MAILEDH="$MAILED $DEVICE"
MAILED=$MAILEDH
# put further action here like cleaning
# up */tmp dirs...
fi
elif [ -n "`echo $MAILED | grep -w $DEVICE`" ] ; then
# Remove mailed marker if enough disk space
# again. So we are ready for new mailing action.
MAILEDH="`echo $MAILED | sed s#$DEVICE##`"
MAILED=$MAILEDH
fi
done
sleep $SLEEPTIME
done
</PRE>
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="console"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
Console Trick Follow-up
</H3>
Date: Wed, 27 Nov 1996 16:20:06 -0500 (EST)<BR>
From: Elliot Lee, <A HREF="mailto:sopwith@cuc.edu">sopwith@cuc.edu </A><BR>
<P>
Just finished reading issue #12, nice work.
<P>
A followup to the "Console Tricks" 2-cent tip: <BR>
What I like to do is have a line in /etc/syslog.conf that says:
<PRE>
*.* /dev/tty10
</PRE>
that sends all messages to VC 10, so I can know what's going on whether in
X or text mode. Very useful IMHO.
<P>
-- Elliot, http://www.redhat.com/
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="gif"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
GIF Animations
</H3>
Date: Thu, 28 Nov 1996 20:41:22 -0600 (CST) <BR>
From: Greg Roelofs, <A HREF="mailto:newt@pobox.com">newt@pobox.com </A>
<P>
I too thought WhirlGIF (Graphics Muse, issue 12) was the greatest thing
since sliced bread (well, aside from PNG) when I first discovered it, but
for creating animations, it's considerably inferior to Andy Wardley's
<A HREF="http://www.peritas.com/~abw/multigif.html">MultiGIF</A>. The
latter can specify tiny sprite images as parts of the animation, not just
full images. For my PNG-balls animation (see http://quest.jpl.nasa.gov/PNG/),
this resulted in well over a factor-of-two reduction in size (577k to 233k).
For another animation with a small, horizontally oscillating (Cylon eyes)
sprite, the savings was more than a factor of 20(!).
<P>
MultiGIF is available as source code, of course. (And I had nothing to do
with it, but I do find it darned handy.)
<P>
Regards, <BR>
Greg Roelofs, http://pobox.com/~newt/ <BR>
Newtware, Info-ZIP, PNG Group, U Chicago, Philips Research, ...
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="adm"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
Re: How to close and reopen a new /var/adm/messages file
</H3>
Date: Thu, 05 Dec 1996 01:09:27 -0800 <BR>
From: CyberTech, <A HREF="mailto:CyberTech@ns.cybertech.org">CyberTech@ns.cybertech.org</A><BR>
<P>
Regarding the posting in issue #12 of your gazette, how to backup the
current messages file & recreate, here is an alternative method...
<P>
Place the lines at the end of this messages in a shell script
(/root/cron/swaplogs in this example). Don't forget to make it +x!
Execute it with 'sh scriptname', or by adding the following lines to
your (root's) crontab:
<PRE>
# Swap logfiles every day at 1 am, local time
0 01 * * * /root/cron/swaplogs
</PRE>
The advantage to this method over renaming the logfile and creating a
new one is that in this method, syslogd is not required to be restarted.
<PRE>
#!/bin/sh
cp /var/adm/messages /var/adm/messages.`date +%d-%m-%y_%T`
cat /dev/null >/var/adm/messages
cp /var/adm/syslog /var/adm/syslog.`date +%d-%m-%y_%T`
cat /dev/null >/var/adm/syslog
cp /var/adm/debug /var/adm/debug.`date +%d-%m-%y_%T`
cat /dev/null >/var/adm/debug
</PRE>
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="admin"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
How to truncate /var/adm/messages
</H3>
Date: Mon, 02 Dec 1996 16:47:20 +0100 <BR>
From: Eje Gustafsson, <A HREF="mailto:gne@ffa.se">gne@ffa.se </A> <BR>
<PRE>
>In answer to the question:
>
> What is the proper way to close and reopen a new >/var/adm/messages
> file from a running system?
>
> Step one: rename the file. Syslog will still be writing in it >after renaming so you don't
> lose messages. Step two: create a new one. After re-initializing >syslogd it will be used.
>just re-initialize.
>
> 1.mv /var/adm/messages /var/adm/messages.prev
> 2.touch /var/adm/messages
> 3.kill -1 pid-of-syslogd
>
> This should work on a decent Unix(like) system, and I know Linux >is one of them.
</PRE>
This is NOT an proper way of truncate /var/adm/messages.
<P>
It is better to do: <BR>
<ol>
<li>cp /var/adm/messages /var/adm/messages.prev
<li>&gt;/var/adm/messages or cp /dev/null /var/adm/messages
(both of them makes the file empty).
<li>No more.
</ol>
The problem is that when you remove the /var/adm/messages syslogd
gets confused and unhappy and you have to give syslogd a HUPSIG
but if you just sets the file length to zero without removing the file
syslogd don't complain. And if you are really unlucky your system
will go down because you didn't create /var/adm/messages quick enough
or forgot it.
<P>
Best of regards, <BR>
Eje Gustafsson, System Administrator <BR>
THE AERONAUTICAL RESEARCH INSTITUTE OF SWEDEN <BR>
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="infozip"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
Info-ZIP encryption code
</H3>
Date: Thu, 28 Nov 1996 20:58:39 -0600 (CST) <BR>
From: Greg Roelofs, <A HREF="mailto:newt@pobox.com">newt@pobox.com</A><BR>
<P>
This is a relatively minor point, but Info-ZIP's Zip/UnZip encryption
code is *not* DES as reported in Robert Savage's article (LG issue 12).
It's actually considerably weaker, so much so that Paul Kocher has pub-
lished a known-plaintext attack (the existence of which is undoubtedly
the reason PKWARE was granted an export license for the code). While
the encryption is good enough to keep your mom and probably your boss
from reading your files, those who desire *real* security should look
to PGP (which is also based on Info-ZIP code, but only for compression).
<P>
And while I'm at it, Linux users will be happy to learn that the upcoming
releases of UnZip 5.3 and Zip 2.2 will be noticeably faster than the cur-
rent publicly released code. In Zip's case this is due to a work-around
for a gcc bug that prevented a key assembler routine from being used--Zip
is now 30-40% faster on large files. In UnZip's case the improvement is
due to a couple of things, one of which is simply better-optimized CRC
code. UnZip 5.3 is about 10-20% faster than 5.2, I believe. The new ver-
sions should be released in early January, if all goes well. And then...
we start working on multi-part archives. :-)
<P>
Greg Roelofs, http://pobox.com/~newt/ <BR>
Newtware, Info-ZIP, PNG Group, U Chicago, Philips Research, ...
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="kernel"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
Kernel Compile Woes
</H3>
Date: Mon, 2 Dec 1996 21:35:29 +0400 (GMT-4)<BR>
From: Duncan Hill, <A HREF="mailto:dhill@sunbeach.net">dhill@sunbeach.net</A><BR>
<P>
Greetings. Having been through hell after a recompile of my kernel, I
thought I'd pass this on.
<P>
It all started with me compiling a kernel for JAVA binary support..who
tell me do that. Somehow I think I got experimental code in..even worse :>
Anyway, it resulted in a crash, and I couldn't recompile since then.
<P>
Well, after several cries for help, and trying all sorts of stuff, I
upgraded binutils to 2.7.0.3, and told the kernel to build elf support and
in elf format, and hey presto. I'd been wrestling with the problem for
well over a week, and every time, I'd get an error. Unfortunately, I had
to take out sound support, so I'm going to see if it'll add back in.
<P>
I have to say thank you to the folks on the linux-kernel mailing list at
vger.rutgers.edu. I posted there once, and had back at least 5 replies in
an hour. (One came back in 10 minutes).
<P>
As for the LG, it looks very nice seen thru Lynx 2-6 (no graphics to get
messed up :>) I love the Weekend Mechanic, and the 2 cent tips mainly.
Perhaps one day I'll contribute something,.
<P>
Duncan Hill, Student of the Barbados Community College
http://www.sunbeach.net/personal/dhill/dhill.htm
http://www.sunbeach.net/personal/dhill/lynx/lynx-main.html
<p><hr><p>
<!--================================================================-->
</td> </tr> </table>
<a name="title"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<h3><img align=bottom alt=" " src="../gx/lil2cent.gif">
Letter 1 to the LJ Editor re Titlebar
</h3>
Date: Sat, 21 Dec 1996 15:18:01 -0600 <br>
From: Roger Booth, <a
href="mailto: Roger_Booth@crow.bmc.com">Roger_Booth@crow.bmc.com</a><br>
To: linux@ssc.com
The Jan97 Issue 33 of <i>Linux Journal</i> contained the "Linux Gazette Two
Cent Tips".
I was interested in the tip "X Term Titlebar Function". Although
the text of the tip stated that the tip would work in ksh-based
systems, I could not get it to work as shown. I think there are
three problems. First, I think there are a few transcription
errors in the script. Second, I believe the author is using
embedded control characters and it was not obvious to me which
character sequences are representations of control characters
and which characters should be typed verbatim. Third, the
author uses a command-line option to the echo command which
is not available on all Unix platforms.
<p>
I finally used the following script:
<pre>
if [ ${SHELL##/*/} = "ksh" ] ; then
if [[ $TERM = x"term" ]] ; then
HOSTNAME=`uname -n`
label () { echo "\\033]2;$*\\007\\c"; }
alias stripe='label $LOGNAME on $HOSTNAME - ${PWD#$HOME/}'
cds () { "cd" $*; eval stripe; }
alias cd=cds
eval stripe
fi
fi
</pre>
I don't use vi, so I left out that functionality.
<p>
The functional changes I made are all in the arguments to the
echo command. The changes are to use \\033 rather than what
was shown in the original tip as ^[, to use \\007 rather than
^G, and to terminate the string with \\c rather than use the
option -n.
<p>
On AIX 4.1, the command &quot;echo -n hi&quot; echoes &quot;-n hi&quot;; in
other
words, -n is not a portable command-line option to the echo
command. I tested the above script on AIX 3.2, AIX 4.1,
HPUX 9.0, HPUX 10.0, Solaris 2.4 and Solaris 2.5. I'm still
trying to get Linux and my Wintel box mutually configured,
so I haven't tested it on Linux.
<p>
I have noticed a problem with this script. I use the rlogin
command to log in to a remote box. When I exit from the
remote box, the caption is not updated, and still shows the
hostname and path that was valid just before I exited. I tried
adding
<pre>
exits () { "exit" $*; eval stripe; }
alias exit=exits
</pre>
and
<pre>
rlogins () { "rlogin" $*; eval stripe; }
alias rlogin=rlogins
</pre>
Neither addition updated the caption to the host/path
returned to. Any suggestions?
<p>
Roger Booth, rbooth@bmc.com
<p><hr><p>
<!--================================================================-->
</td> </tr> </table>
<a name="more"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<h3><img align=bottom alt=" " src="../gx/lil2cent.gif">
Letter 2 to the LJ Editor re Titlebar
</h3>
Date: Fri, 13 Dec 1996 23:03:37 -0700 (MST)
From: Gary Masters, <A HREF="mailto:gmasters@csn.net">gmasters@csn.net</A><BR>
<P>
Some further clarification is needed with respect to the X Term Titlebar
Function tip in the Linux Gazette Two Cent Tips column of the January
1997 issue. With regard to the -print option to find, Michael Hammel
says, &quot;Linux does require this.&quot; This is yet another example of &quot;Your
mileage may vary.&quot; Some versions of Linux do not require the -print
option. And, although Solaris may not, SunOS 4.1.3_U1 and 4.1.4 do
require the -print option. Also, if running csh or tcsh, remember to
escape wildcards in the file specification ( e.g. find ./ -name \*txt\* )
so that the shell doesn't attempt to expand them.
<P>
Second, for those tcsh fans out there, here is an xterm title bar function
for tcsh.
<P>
NOTE: This works on Slackware 3.0 with tcsh version 6.04.00, under the
tab, fv, and OpenLook window managers. Your mileage may vary.
<pre>
if ( $TERM == xterm ) then
set prompt="%h> "
alias cwdcmd 'echo -n "^[]2;`whoami` on ${HOST} - $cwd^G^[]1;${HOST}^G"'
alias vi 'echo -n "^[]2;${HOST} - editing file-> \!*^G" ; vim \!* ;
cwdcmd'
alias telnet '/bin/telnet \!* ; cwdcmd'
alias rlogin '/usr/bin/rlogin \!* ; cwdcmd'
cwdcmd
else
set prompt="[%m]%~% "
endif
</PRE>
<ol>
<li>Check to see if tcsh is running in an xterm.
<li>Set the prompt to show the current history event number.
<li>Set the alias cwdcmd to display the user, host, and current path in
the xterm title bar, and set the icon name to the host name. cwdcmd
is a special tcsh alias, which if set holds a command that will be
executed after changing the value of $cwd.
<li>Set a vi alias to display the user, host, and file name under edit in
the xterm title bar. And run cwdcmd on exit to restore the xterm
title bar and icon name.
<li>Alias telnet and rlogin to restore the xterm title bar and icon name
upon exit. NOTE: Paths to telnet and rlogin may vary.
<li>Run the alias cwdcmd to set the initial xterm title bar and icon name.
<li>If this wasn't an xterm, set the prompt to show hostname and path.
</ul>
Gary Masters
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="redial"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
PPP redialer script--A Quick Hack
</H3>
Date: Sun, 08 Dec 1996 13:20:25 +0200 <BR>
From: Markku J. Salama, <A
HREF="mailto:msalama@usa.net">msalama@usa.net</A><BR>
<P>
This here is the way I do it, but don't use it if your area has some
regulations
about redialing the same phone numbers over and over:
<PRE>
#!/bin/sh
# A quick hack for redialing with ppp by <root@superfly.salama.fi>
# Tries 2 numbers sequentially until connected
# Takes 1 cmdline parm, the interface (ppp0, ppp1...)
# You need 2 copies of the ppp-on script (here called modemon{1,2}) with
# different telephone numbers for the ISP. These scripts should be
slightly
# customized so that the passwd is _not_ written in them, but is taken
# separately from the user in the main (a.k.a. this) script.
# Here's how (from the customized ppp-on a.k.a. modemon1):
# ...
# TELEPHONE=your.isp.number1 # Then make a copy of this script ->
modemon2
# and change this to your.isp.number2
# ACCOUNT=your.account
# PASSWD=$1 # This gets the passwd from the main
script.
# ...
# /sbin/ifconfig must be user-executable for this hack to work.
wd1=1 # counter start
stty -echo # echo off
echo -n "Password: " # for the ISP
account
read wd2
stty echo # back on
echo
echo "Trying..."
echo 'ATE V1 M0 &K3 &C1 ^M' > /dev/modem # modem init,
# change as
needed
/usr/sbin/modemon1 $wd2 # first try
flag=1 # locked
while [ 1 ]; do # just keep on
going
if [ "$flag" = 1 ]; then # locked?
bar=$(ifconfig | grep -c $1) # check for a link
if [ "$bar" = 1 ]; then # connected?
echo "Connected!" # if so, then
exit 0 # get outta here
else
foo=$(ps ax) # already
running?
blaat=$(echo $foo | grep "/usr/sbin/pppd")
if [ "$blaat" = "" ]; then # if not, then
flag=0 # unset lock
fi
fi
else # no lock, ready
# to continue
wd1=$[wd1+1]
echo "Trying again... $wd1"
if [ $[wd1%2] = 1 ]; then # this modulo
test
/usr/sbin/modemon1 $wd2 # does the
switching
else # between the 2
numbers
/usr/sbin/modemon2 $wd2 # we are using
fi
flag=1 # locked again
fi
done # All done!
</PRE>
There. Customize as needed & be an excellent person. Ant DON'T break any
laws if redialing is illegal in your area!
<P>
Mark
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="table"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
TABLE tags in HTML
</H3>
Date: Fri, 20 Dec 1996 11:51:22 -0500 <BR>
From: Michael O'Keefe, <A HREF="mailto:Michael.OKeefe@LMC.Ericsson.SE">
Michael.OKeefe@LMC.Ericsson.SE </A> <BR>
Organization: Ericsson Research Canada <BR>
<P>
G'day,
<P>
Just browsing through the mailbox, and I noticed your reply to a user
about HTML standard compliance and long download times. You replied that
you use the spiral image (a common thing these days) inside a &lt;TABLE&gt;.
<P>
I hope you are aware that a browser cannot display any contents of a
&lt;TABLE&gt; until it has received the &lt;/TABLE&gt; tag (no matter what version
of any browser - it is a limitation of the HTML tag) because the browser
cannot run its algorithm until it has received all of the &lt;TR&gt; and
&lt;TD&gt; tags, and it can't be sure of that until the &lt;/TABLE&gt; linux-questions-only@ssc.comes
through. I have seen many complex sites, using many images (thankfully
they at least used the HEIGHT and WIDTH tags on those images to tell
the browser how big the image will be so it didn't have to download
it to find out) but still, putting it in a table nullifies much of the
speediness that users require.
<P>
A solution I often offer the HTML designers under me is to use a
&lt;DL&gt;&lt;DD&gt; combination. Though this doesn't technically fit the HTML DTD
(certain elements are not allowed in a &lt;DL&gt;) and I use an editor that
will not allow illegal HTML, so I can't do it myself (without going
via a backdoor - but that's bad quality in my opionion). The downside
of the this is of course that you don't know what sized FONT the user
has set on the browser, and the FONT size affects the indetation width
of the &lt;DD&gt; element. But if your spiral image is not too wide, then
that could be made a NULL factor. The plus to the &lt;DL&gt;&lt;DD&gt; is that the
page can be displayed instantly as it comes down (again..providing the
developer uses the HEIGHT and WIDTH attributes on *ALL* images so that
the browser doesn't have to pause it's display to get the image and work
out how to lay out around the image)
<p>
Michael O'Keefe
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="undelete"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
Text File undelete
</H3>
Date: Sat, 7 Dec 1996 15:00:58 +1300 (NZDT) <BR>
From: Michael Hamilton, <A HREF="mailto:michael@actrix.gen.nz">
michael@actrix.gen.nz </A> <BR>
<P>
Here's a trick I've had to use a few times.
<P>
Desperate person's text file undelete.
<P>
If you accidentally remove a text file, for example, some email, or
the results of a late night programming session, all may not be lost.
If the file ever made it to disk, ie it was around for more than 30
seconds, its contents may still be in the disk partition.
<P>
You can use the grep command to search the raw disk partition for the
contents of file.
<P>
For example, recently, I accidentally deleted a piece of email.
So I immediately ceased any activity that could modify that partition:
in this case I just refrained from saving any files or doing any compiles
etc. On other occasions, I've actually gone to the trouble of bring the
system down to single user mode, and unmounted the filesystem.
<P>
I then used the egrep command on the disk partition: in my case the email
message was in /usr/local/home/michael/, so from the output from df,
I could see this was in /dev/hdb5
<PRE>
sputnik3:~ % df
Filesystem 1024-blocks Used Available Capacity Mounted on
/dev/hda3 18621 9759 7901 55% /
/dev/hdb3 308852 258443 34458 88% /usr
/dev/hdb5 466896 407062 35720 92% /usr/local
sputnik3:~ % su
Password:
[michael@sputnik3 michael]# egrep -50 'ftp.+COL' /dev/hdb5 > /tmp/x
</PRE>
Now I'm ultra careful when fooling around with disk partitions, so I
paused to make sure I understood the command syntax BEFORE pressing
return. In this case the email contained the word 'ftp' followed by
some text followed by the word 'COL'. The message was about 20 lines
long, so I used -50 to get all the lines around the phrase. In the
past I've used -3000 to make sure I got all the lines of some source
code. I directed the output from the egrep to a different disk
partition - this prevented it from over writing the message I was
looking for.
<P>
I then used strings to help me inspect the output
<PRE>
strings /tmp/x | less
</PRE>
Sure enough the email was in there.
<P>
This method can't be relied on, all, or some, of the disk space may
have already been re-used.
<P>
This trick is probably only useful on single user systems. On
multi-users systems with high disk activity, the space you free'ed up
may have already been reused. And most of use can't just rip the box
out from under our users when ever we need to recover a file.
<P>
On my home system this trick has come in handy on about three
occasions in the past few years - usually when I accidentally trash
some of the days work. If what I'm working survives to a point where
I feel I made significant progress, it get's backed up onto floppy, so
I haven't needed this trick very often.
<P>
Michael
<p><hr><p>
<!--================================================================-->
</td> </tr> </table>
<a name="var"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<h3><img align=bottom alt=" " src="../gx/lil2cent.gif">
Truncating /var/adm/messages
</h3>
Date: Tue, 31 Dec 1996 15:32:57 GMT+100 <BR>
From: Michel Vanaken, <A HREF="mailto:michel@idtech.be">michel@idtech.be</A><BR>
Organization: IDtech <BR>
<P>
Hi !
<P>
About the topic &quot;How to truncate /var/adm/messages&quot;, here's the way
to do it with a shell script :
<pre>
mv /var/adm/messages /var/adm/messages.prev
touch /var/adm/messages
mv /var/adm/syslog /var/adm/syslog.prev
touch /var/adm/syslog
kill -1 `ps x | grep syslog | grep -v grep | awk '{ print $1 }'`
</pre>
Happy new year ! <BR>
Michel
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="host"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
2c Host Trick
</H3>
Date: Tue, 10 Dec 1996 17:27:46 +0300 <BR>
From: Paul Makeev, <A HREF="mailto:mac@rosprint.ru">mac@rosprint.ru</A><BR>
<P>
In order to make DHCPD by ISC/Vixie to run under Linux, you should
have route to host 255.255.255.255. Standard "route" from Slackware
distribution does not like the string "route add -host 255.255.255.255
dev eth0". But you can add hostname to your /etc/hosts file with
address 255.255.255.255, and use "route add hostname dev eth0" instead.
It works.
<P>
Paul.
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="tcsh"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
Use of TCSH's :e and :r Extensions
</H3>
Date: Mon, 02 Dec 1996 23:25:23 -0500 <BR>
From: Bill C. Riemers, <A HREF="mailto:bcr@feynman.com">bcr@feynman.com</A><BR>
<P>
I'd like to congratulate Jesper Pedersen on his article on tcsh
tricks. Tcsh has long been my favorite shell. But most of the features
Jesper hit upon are also found in bash. Tcsh's most useful and unique
features are its variable/history suffixes.
<P>
For example, if after applying a patch one wishes to undo things, by
moving the *.orig files to there base names, the :r extension which
means to strip the extension comes in handy. e.g.
<PRE>
foreach a ( *.orig )
mv $a $a:r
end
</PRE>
The same loop for ksh looks like:
<PRE>
for a in *.orig; do=20
mv $a `echo $a|sed -e 's,\.orig$,,g'`
done
</PRE>
Even better, one can use the :e extension to extract the file extension.
For example, lets say we we want to do the same thing on compressed
files:
<PRE>
foreach a ( *.orig.{gz,Z} )
mv $a $a:r:r.$a:e
end
</PRE>
The $a:r:r is the filename without .orig.gz and .orig.Z, we tack the
.gz or .Z back on with .$a:e.
<P>
Bill
<P> <hr> <P>
<!--================================================================-->
</td> </tr> </table>
<a name="notes"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
Various notes on 2c tips, Gazette 12
</H3>
Date: Wed, 04 Dec 1996 15:30:21 -0600 <BR>
From: Justin Dossey, <A HREF="mailto:dossey@ou.edu">dossey@ou.edu </A> <BR>
<P>
I noticed a few overly difficult or unnecessary procedures recommended
in the 2c tips section of Issue 12. Since there is more than one, I'm
sending it to you:
<PRE>
#!/bin/sh
# lowerit
# convert all file names in the current directory to lower case
# only operates on plain files--does not change the name of
directories
# will ask for verification before overwriting an existing file
for x in `ls`
do
if [ ! -f $x ]; then
continue
fi
lc=`echo $x | tr '[A-Z]' '[a-z]'`
if [ $lc != $x ]; then
mv -i $x $lc
fi
done
</PRE>
Wow. That's a long script. I wouldn't write a script to do that;
instead, I would use this command:
<PRE>
for i in * ; do [ -f $i ] && mv -i $i `echo $i | tr '[A-Z]' '[a-z]'`;
done;
</PRE>
on the command line.
<P>
The contributor says he wrote the script how he did for
understandability (see below).
<P>
On the next tip, this one about adding and removing users, Geoff is
doing fine until that last step. Reboot? Boy, I hope he doesn't reboot
every time he removes a user. All you have to do is the first two
steps. What sort of processes would that user have going, anyway? An
irc bot? Killing the processes with a simple
<PRE>
kill -9 `ps -aux |grep ^<username> |tr -s " " |cut -d " " -f2`
</PRE>
Example, username is foo
<PRE>
kill -9 `ps -aux |grep ^foo |tr -s " " |cut -d " " -f2`
</PRE>
That taken care of, let us move to the forgotten root password.
<P>
The solution given in the Gazette is the most universal one, but not the
easiest one. With both LILO and loadlin, one may provide the boot
parameter &quot;single&quot; to boot directly into the default shell with no login
or password prompt. From there, one may change or remove any passwords
before typing ``init 3``to start multiuser mode.
Number of reboots: 1
The other way
Number of reboots: 2
<P>
That's just about it. Thanks for the great magazine and continuing
contribution to the Linux community. The Gazette is a needed element
for many linux users on the 'net.
<P>
Justin Dossey
<P>
Date: Wed, 4 Dec 1996 08:46:24 -0800 (PST) <BR>
Subject: <B> Re: lowerit shell script in the LG </B> <BR>
From: Phil Hughes, <A HREF="mailto:phil@ssc.com">phil@ssc.com </A> <BR>
<P>
The amazing Justin Dossey wrote:
<PRE>
> #!/bin/sh
> for i in * ; do [ -f $i ] && mv -i $i `echo $i | tr '[A-Z]' '[a-z]'`;
> done;
>
> may be more cryptic than
...
>
> but it is a lot nicer to the system (speed & memory-wise) too.
</PRE>
Can't argue. If I had written it for what I considered a high usage
situation I would have done it more like you suggested. The intent,
however, was to make something that could be easily understood.
<P>
Phil Hughes
<p><hr><p>
<!--================================================================-->
</td> </tr> </table>
<a name="howto"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<h3><img align=bottom alt=" " src="../gx/lil2cent.gif">
Viewing HOWTO Documents
</h3>
Date: Sun, 22 Dec 1996 09:43:40 -0800 <br>
From: Didier Juges, <a
href="mailto:dj@destin.nfds.net">dj@destin.nfds.net</a><br>
<p>
>From a newbie to another, here is a short script that eases looking for
and viewing howto documents.
My howto's are in /usr/doc/faq/howto/ and are gzipped. The file names are
XXX-HOWTO.gz, XXX being the subject.
I created the following script called "howto" in the /usr/local/sbin
directory:
<pre>
#!/bin/sh
if [ "$1" = "" ]; then
ls /usr/doc/faq/howto | less
else
gunzip -c /usr/doc/faq/howto/$1-HOWTO.gz | less
fi
</pre>
When called without argument, it displays a directory of the available
howto's. Then when entered with the first part of the file name (before
the hyphen) as an argument, it unzips (keeping the original intact) then
displays the document.
<p>
For instance, to view the Serial-HOWTO.gz document, enter:
$ howto Serial
<p>
Keep up the good work.
<p>
Didier
<p><hr><p>
<!--================================================================-->
</td> </tr> </table>
<a name="xaw"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<h3><img align=bottom alt=" " src="../gx/lil2cent.gif">
Xaw-XPM .Xresources troubleshooting tip.
</h3>
Date: Wed, 18 Dec 1996 17:02:07 +0100 (GMT+0100) <br>
From: Robin Smidsroed, <a
href="mailto:dex@sysedata.no">dex@sysedata.no</a><br>
<p>
I'm sure a lot of you folks out there have installed the new Xaw-XPM and
like it a lot. But I've had some trouble with it. If I don't install the
supplied .Xresources-file, xcalc and some other apps (ghostview is one)
segfaults whenever you try to use them.
<p>
I found out that the entry which causes this, is this:
<pre>
*setPixmap: /path/to/an/xpm-file
</pre>
If this entry isn't in your .Xresources, xcalc and ghostview won't work. Hope
some of you out there need this.
<p>
And while you're at ghostview, remember to upgrade ghostscript to the latest
version to get the new and improved fonts, they certainly look better on
paper than the old versions.
<p>
Ciao! <br>
Robin
<p>
PS: Great mag, now I'm just waiting for the arrival of my copy of LJ
<p><hr><p>
<!--================================================================-->
</td> </tr> </table>
<a name="xterm"><p></a>
<table>
<td><img src="../gx/blank.gif" width=50></td>
<td>
<h3><img align=bottom alt=" " src="../gx/lil2cent.gif">
xterm title bar
</h3>
Date: Wed, 18 Dec 1996 21:21:47 -0800 (PST)
From: bradshaw@nlc.com (Lee Bradshaw)
<p>
Hi Guys,
<p>
I noticed the &quot;alias for cd xterm title bar tip&quot; from Michael
Hammel in
the <i>Linux Gazette</i> and wanted to offer a possible improvement for your
.bashrc file. A similar solution might work for ksh, but you may need
to substitute $HOSTNAME for \h, etc:
<pre>
if [ "x$TERM" = "xxterm" ]; then
PS1='\h \w-> \[\033]0;\h \w\007\]'
else
PS1='\h \w-> '
fi
</pre>
PS1 is an environment variable used in bash and ksh for storing the
normal prompt. \h and \w are shorthand for hostname and working
directory in bash. The \[ and \] strings enclose non-printing
characters from the prompt so that command line editing will work
correctly. The \O33]0; and \007 strings enclose a string which
xterm will use for the title bar and icon name. Sorry, I don't
remember the codes for setting these independently. (ksh users note:
\033 is octal for ESC and \007 is octal for CTRL-G.) This example just
changes the title bar and icon names to match the prompt before the
cursor.
<p>
Any program which changes the xterm title will cause inconsistencies if
you try an alias for cd instead of PS1. Consider rlogin to another
machine which changes the xterm title. When you quit rlogin, there is
nothing to force the xterm title back to the correct value when using
the cd alias (at least not until the next cd). This is not a problem
when using PS1.
<p>
You could still alias vi to change the xterm title bar, but it may not
always be correct. If you use ":e filename" to edit a new file, vi
will not update the xterm title. I would suggest upgrading to vim (VI
iMproved). It has many nice new features in addition to displaying the
current filename on the xterm title.
<p>
Hopefully this tip is a good starting point for some more experimenting.
Good luck!
<p>
Lee Bradshaw, bradshaw@nlc.com
<P> <hr> <P>
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