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<H4>"Linux Gazette...<I>making Linux just a little more fun!</I>"
</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>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
<FONT COLOR="navy">2 Cent Trick: handy dictionary
</FONT> </H3>
Fri, 10 Mar 2000 16:52:05 -0800
<BR>From: Bryan Henderson &lt;<A HREF="mailto:bryanh@giraffe-data.com">bryanh@giraffe-data.com&gt;</A>
<P> A writer should never forego looking up a word in the dictionary
because it's too much effort. Here's a way to have a dictionary at
your fingertips if you're connected to the Internet: Make a shell
script 'dict' that does
<PRE>
lynx "http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&amp;va=$*"
</PRE>
<P> Now the shell command
<P> dict quotidian
<P> Brings up a definition of "quotidian".
<P> I use Lynx instead of wget because the dictionary page has links on it
I might want to follow (such as alternate spellings and synonyms). I
use Lynx instead of something graphical because it is fast.
<P> <hr> <P>
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<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
<FONT COLOR="navy">faq_builder.pl script
</FONT> </H3>
Sat, 11 Mar 2000 07:08:15 +0100 (CET)
<BR>From: Hans Zoebelein &lt;<A HREF="mailto:hzo@goldfish.cube.net">hzo@goldfish.cube.net&gt;</A>
<P> Everybody who is running a software project needs a FAQ to clarify
questions about the project and to enlighten newbies how to run
the software. Writing FAQs can be a time consuming process without much
fun.
<P> Now here comes a little Perl script which transforms simple ASCII input
into HTML output which is perfect for FAQs (Frequently Asked Questions).
I'm using this script on a daily basis and it is really nice and spares
a lot of time. Check out http://leb.net/blinux/blinux-faq.html for
results.
<P> Attachment faq_builder.txt is the ASCII input to produce faq_builder.html
using faq_builder.pl script.
<P> 'faq_builder.pl faq_builder.txt &gt; faq_builder.html'
<P> does the trick. Faq_builder.html is the the description how to use
faq_builder.pl.
<P> <A HREF="misc/tips/faq_builder.pl.txt">faq_builder.pl</A><BR>
<A HREF="misc/tips/faq_builder.html">faq_builder.html</A><BR>
<A HREF="misc/tips/faq_builder.txt">faq_builder.txt</A>
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
<FONT COLOR="navy">winmodems
</FONT> </H3>
Tue, 14 Mar 2000 20:09:41 -0500
<BR>From: Les Urban &lt;<A HREF="mailto:lnaa@centurytel.net">lnaa@centurytel.net&gt;</A>
<P> Well I'm a Linux newbie. Been in DP for 25 years and wanted something
better. I'm running SuSE 6.3 and having fun. Really close to wiping WINDOZE
from my hard disk. I've really enjoyed your site and have found many answers to
the many questions that have been starring me in the face. Keep up the good
work.
<P> Read another article about winmodems being dead wood as far as Linux is
concerned. I got a great deal I thought at Best Buys a 56k modem for 9.95. Of
course I should have know it had to be a winmodem. But I stumbled on the site
<A HREF="http://linmodems.org">linmodems.org</A> There are alot of people
working on this issue. In fact LUCENT has provided a binary for their LT
MODEMS. Well I downloaded that guy and I'm running great on my winmodem. There
are other drivers available for other modems. Some are workable and some are
still in development. I believe it's worth taking a look and spreading the
word. You can reach alot more than I can.
<P> Once again great site and thank you for all the helpful hints. I'll
continue to be a steady visitor and a Linux advocate.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
<FONT COLOR="navy">Fantastic book on linux - available for free both on/offline!
</FONT> </H3>
Sat, 18 Mar 2000 16:15:22 GMT
<BR>From: Esben Maal&oslash;e (Acebone) &lt;<A HREF="mailto:acebone@f2s.com
">acebone@f2s.com&gt;</A>
<P> Hi!
<P> When I browse through the 2 cent tips, I see a lot of general
Sysadmin/bash questions that could be answered by a book called "An
Introduction to Linux Systems Administration" - written by David Jones
and Bruce Jamieson.
<P> You can check it out at
<A HREF="http://www.infocom.cqu.edu.au/Units/aut99/85321">
www.infocom.cqu.edu.au/Units/aut99/85321</A>
<P> It's available both on-line and as downloadable PostScript file.
Perhaps it's also available in PDF.
<P> It's a great book, and a great read!
<!-- END tips -->
<P> <hr> <P>
<!--================================================================-->
<H4><font color="maroon">
Tips in the following section are answers to questions printed in the Mail
Bag column of previous issues.
</font></H4>
<!-- BEGIN tips.answers -->
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: help in printing numbered pages!
</FONT> </H3>
Wed, 01 Mar 2000 07:48:30 GMT
<BR>From: Anthony E. Greene &lt;<A HREF="mailto:agreene@pobox.com">agreene@pobox.com&gt;</A>
<BLOCKQUOTE>
<P> I usualy print a lot of documentation. One thing that I would like
to make is that my print jobs gets the pages to be numbered. So at the
bottom of the pages we could see "page 1/xx" , etc. I had looked a
while for info in how to set this up, but could not find. The printtool
just dont do it. Maybe i should to create a filter, but what commands
must i use to make this heapppens???
</BLOCKQUOTE>
<P> It depends on the software you used to create the file. If it is a plain
text file, you can use "pr" to print it with page numbers in the header:
<PRE>
pr -f -l 55 somefile.txt | lpr
</PRE>
<P> If the file is HTML, there is a utility html2ps that will do what you
need. It's available at
<A HREF="http://www.tdb.uu.se/~jan/html2ps.html">
http://www.tdb.uu.se/~jan/html2ps.html</A>. It
converts HTML to PostScript with an option for page numbers and other
things.
<P> If you are using a word processor, it may have an option to include page
numbers. Let us know what you are trying to print and we may be able to
give better help.
<H4>Jos&eacute; A. Gaeta Mendes &lt;<A HREF="mailto:gaeta@ecosfera.com.br">gaeta@ecosfera.com.br&gt;</A> suggests</H4>
<P> See emacs *Tools | Print | Postscript Print Buffer* command...
It does exactly what you want!
<P> [ ]s - J. A. Gaeta Mendes
Greetings from Brazil!
<H4>Michal Jaegermann &lt;<A HREF="mailto:michal@ellpspace.math.ualberta.ca">michal@ellpspace.math.ualberta.ca&gt;</A> suggests</H4>
<P> 'man pr'
<P> For fancier output with various bells and whistles
<P> 'man nenscript'
<P> (plus maybe a driver script, or two, to get your customizations).
<P> Michal
<H4>Bob Ternosky &lt;<A HREF="mailto:rternosk@appliedtheory.com">michal@ellpspace.math.ualberta.ca&gt;</A> suggests</H4>
<P> Try the 'mpage' command.
<P> It wont work for everything but it uses a header and page numbers
and can also print multiple pages of stuff per page (saves paper).
<P> Example:
<PRE>
mpage -2 -H document | lpr
</PRE>
<P> (prints 2 pages on one, and puts a header w/ filename, page numbers)
<P> Hope this helps.
<H4>From: Clovis Sena &lt;<A HREF="mailto:csena@itautec-philco.com.br">csena@itautec-philco.com.br</A>&gt;</H4>
<P> Thanks Bob and everybody who helped me!
Now I am using mpage to print. That makes more sense, saving paper and
toner.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: Inexpensive, powerful db's for Linux?
</FONT> </H3>
Wed, 01 Mar 2000 08:01:11 GMT
<BR>From: Anthony E. Greene &lt;<A HREF="mailto:agreene@pobox.com">agreene@pobox.com&gt;</A>
<BLOCKQUOTE>
To develop a distributed database application that runs on Linux,
what inexpensive, powerful databases might work best?
</BLOCKQUOTE>
<P> Check the Application section at
<A HREF="http://www.linux.org/">Linux.org</A> for
databases. It lists big names such as DB2, Oracle, Informix, Ingres, and
others such as <A HREF="http://www.postgresql.org/">PostgreSQL</A> which is
free, powerful, and ships with Red Hat Linux. The latest beta adds several
desirable features. You may hear a lot about MySQL, but if you're building
anythin more complicated than a basic query system, you'll need something more
powerful than MySQL.
<H4>Marius ANDREIANA &lt;<A HREF="mailto:rocky@ss.pub.ro">rocky@ss.pub.ro&gt;</A> wrote</H4>
<P> PoestgreSQL, by far. www.postgresql.org
Inexpensive ( free, GPL ), powerful ( check the website for
a list of features ), great.
There's also MySQL, but less powerful than Postgres ( performance,
when talking about milions of records, and many more )
<P> Distributed ? PostgreSQL is the database engine, server & client.
You start the server and you can connect to it from any other
machine using TCP/IP. Connect from what ? From what you want :
C, Python, PHP, Perl, etc etc ( see Postgres howto ). A recent
great adition is Gnome-DB ( www.gnome.org/gnome-db/ ), which
gives you the power to develop cool desktop applications.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: linuxconf
</FONT> </H3>
Wed, 1 Mar 2000 06:36:17 -0700 (MST)
<BR>From: &lt;<A HREF="mailto:ghaverla@freenet.edmonton.ab.ca">ghaverla@freenet.edmonton.ab.ca&gt;</A>
<P> I'm just guessing, but are the clocks on all these machines
synchronized? That seems to be one reason why one computer
would continually update another.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Modems
</FONT> </H3>
Wed, 1 Mar 2000 12:20:02 -0300
<BR>From: Juan M. Fera &lt;<A HREF="mailto:jmfera@sion.com">jmfera@sion.com&gt;</A>
<P> Hello:
You can solve your problems by reading the section 20 (Modems) on the Linux Hardware Compatibility HOWTO...
<P> <A HREF="http://www.linuxdoc.org/HOWTO/Hardware-HOWTO-20.html">
http://www.linuxdoc.org/HOWTO/Hardware-HOWTO-20.html</A>
<P> and the section 30 (Appendix E. Linux incompatible Hardware) too...
<P> <A HREF="http://www.linuxdoc.org/HOWTO/Hardware-HOWTO-30.html">
http://www.linuxdoc.org/HOWTO/Hardware-HOWTO-30.html</A>
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">IP Masquerade Connection Problems
</FONT> </H3>
1 Mar 00 08:47:35 PST
<BR>From: Darrell Scott &lt;<A HREF="mailto:scottie99@netscape.net">scottie99@netscape.net&gt;</A>
<P> This is a known bug with the PPP packages distributed with Red Hat 6.1. See
RHEA-1999:051-01 for a full description of the problem, and pointers to
updated packages.
<P> Scottie
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: make virtuald
</FONT> </H3>
Thu, 2 Mar 2000 22:32:07 +0100 (CET)
<BR>From: Roland Smith &lt;<A HREF="mailto:rsmith@xs4all.nl">rsmith@xs4all.nl&gt;</A>
<BLOCKQUOTE>
<P> I am trying to compile virtuald using make virtuald here is the
error I get
<PRE>
Makefile:14: *** missing separator. Stop.
</PRE>
I did a cut and paste of the code from
http://www.linuxdoc.org/HOWTO/Virtual-Services-HOWTO-3.html in the
section 3.4 Source then used ftp to put it on the server in order to
compile it.
</BLOCKQUOTE>
<P> This is a small gotcha with make. See the following makefile snippet:
<PRE>
# Remove all generated files.
clean:;
rm -f $(OBJS) $(BASENAME) *~ core $(TARFILE) $(BACKUP) $(LOG)
</PRE>
<P> The commands that follow a rule (`rm' in this case) should be preceded by a
tab character. Probably, some tabs got converted to spaces when
cutting-and-pasting.
<P> Try editing the Makefile with vi or emacs. Both can insert literal tab
characters, and emacs has a specail mode for makefiles that takes care of
that automagically.
<H4>Darrell Scott &lt;<A HREF="mailto:scottie99@netscape.net">scottie99@netscape.net&gt;</A> suggests</H4>
<P> Hi,
<P> I think you're missing a Makefile!
<P> The "make" command interprets a set of commands in a specifically written
makefile, to compile and link source code into an executable. "gcc" is the
actual compiler/linker, and is appears to be what you actually require in this
case. Try "gcc (source filename goes here) -o virtuald" (it's probably wise
to move your source from virtuald to virtuald.c with the command "mv virtuald
virtuald.c" first).
<P> Scottie
<P> btw, if you did write a makefile, a common gotcha is that at least one
tabspace is required between the label and the commands. Spaces just won't
cut it; you'll end up with the "Missing Separator" message again!
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Linux & win98 internet connection sharing
</FONT> </H3>
Wed, 1 Mar 2000 22:41:07 -0500
<BR>From: DJ Busch &lt;<A HREF="mailto:djbusch@mediaone.net">djbusch@mediaone.net&gt;</A>
<P> Check out a program called WinRoute for Windows 98. You can download a
trial copy from winroute.com. If it's setup right, you can tell your Linux
box that your Win98 box is your "default gateway" and winroute will do the
rest for you. I have 2 W98 boxes, 1 linux box and 1 iMac all running on
this kind of setup and I've never had a problem.
<P> DJ Busch
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: Gazette crashes Konqueror (from LinuxGazette #51/General Mail)
</FONT> </H3>
Thu, 2 Mar 2000 08:41:07 +0000
<BR>From: Jan-Hendrik Terstegge &lt;<A HREF="mailto:helge@jhterstegge.de">helge@jhterstegge.de&gt;</A>
<P> Hi!
<P> In LinuxGazette #51 Pierre Abbat (phma@oltronics.net) wrote:
<BLOCKQUOTE>
I am trying to read the Gazette with kfm 1.167 and several pages crash
it, including the mailbag and 2c Tips. Can you help me figure out
what's wrong? It's happend before.
</BLOCKQUOTE>
In you Subject you wrote the the gazette crashes the konqueror, but in your
text you wrote it is the kfm. What thing do you use? Is the Konqueror your
kfm replacement. Then I think you use a KDE-beta Version. Please try to use
stable releases (I think the last was KDE 1.1.2).
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">AS/400 Emulation
</FONT> </H3>
Thu, 02 Mar 2000 08:25:59 -0500
<BR>From: Vince Du Beau &lt;<A HREF="mailto:vdubeau@ploverdev.com">vdubeau@ploverdev.com&gt;</A>
<BLOCKQUOTE>
From: Jeffrey T. Ownby (jownby@ecsis.net)<BR>
Subject: 5250 terminal for AS400 connection
<P> I am adding a Linux box to a network consisting of several Win9X
and NT machines that use either IBM Client Access or Rumba to connect
to our AS400. Is there a program similar to either one of these that
can provide terminal emulation on Linux. Any info appreciated!
<P> Later,<BR>
Jeffro
</BLOCKQUOTE>
<P> I currently use tn5250 to connect from my laptop to an AS/400 (thru an NT Server). This is a
modified version of telnet with better key mappings. You can find it at:
<A HREF="http://www.blarg.net/~mmadore/5250.html">
http://www.blarg.net/~mmadore/5250.html</A>
<P> IBM also has a java based version of client access which reportedly runs under Linux. I haven't
tried it since it requires some of it to run from the HTTP server on the AS/400. Their link is:
<A HREF="http://www-4.ibm/software/network/hostondemand">
http://www-4.ibm/software/network/hostondemand</A>
<P> Hope this helps.
<P> Vince Du Beau
<H4>From: Jimmy O'Regan &lt;<A HREF="mailto:jimregan@litsu.ie">jimregan@litsu.ie&gt;</A> suggests</H4>
<P> There's a 5250 terminal emulator available at
<A HREF="http://www.linux-sna.org/software/5250/index.html">
http://www.linux-sna.org/software/5250/index.html</A>
<P> We use an AS/400 in the college I attend, and while I haven't been able to
get permission to put a linux box on the same network as the 400 (and
therefore cannot vouch for the linux version) I have tried the WinNT port
of the program, and it works very well. (Though as far as I remember,
there was no way to paste)
<P> But as far as getting the capabilities of client access, you should try
Linux SNA (<A HREF="http://www.linux-sna.org/">
http://www.linux-sna.org/</A>) which adds the AS/400s native
protocol stack to the kernel. There are also some tools which should
provide some of the other capabilities of client access, such as file
transfer.
<P> (If you get it working, please drop me a note, as I'd love some
testimonial to use to convince my college to let me hook up a box to our
as/400).
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Quick tip for mounting FDs, CDs, etc...
</FONT> </H3>
Fri, 25 Feb 2000 15:49:17 -0800
<BR>From: &lt;<A HREF="mailto:fuzzybear@pocketmail.com">fuzzybear@pocketmail.com&gt;</A>
<P> If you can't or don't want to use auto-mounting, and are tired of typing out all those 'mount' and 'umount' commands, here's a script called 'fd' that will do "the right thing at the right time" - and is easily modified for other devices:
<PRE>
#!/bin/bash
d="/mnt/fd0"
if [ -n "$(mount $d 2&gt;&amp;1)" ]; then umount $d; fi
</PRE>
<P> It's a fine example of "obfuscated Bash scripting"<grin>, but it works well - I use it and its relatives 'cdr', 'dvd', and 'fdl' (Linux-ext2 floppy) every day.
<P> Ben Okopnik
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: Pentium-II Xeon and calculation speed
</FONT> </H3>
Sun, 27 Feb 2000 15:19:44 +0100 (CET)
<BR>From: Roland Smith &lt;<A HREF="mailto:rsmith@xs4all.nl">rsmith@xs4all.nl&gt;</A>
<BLOCKQUOTE>
<P> Hi guys, here I'm trying to get a little bit of help with my
computer. I'm doing a very time expensive calculations using FORTRAN
programs, compiled with g77 under Red Hat 6.1. First, on dual
Pentium-II/400MHz and Pentium-III/450MHz computers I noticed, that when
program size (RSS in top) is getting biger that approximately 600K
computation speed dramatically decreasing by factor two. This slowing
down agrees with the bus speed (100MHz) and L2 cache (512K, 200MHz). So,
</BLOCKQUOTE>
<P> What have you done about optimizing your program? Some things you could do:
<UL>
<LI> profile the running application to see where it spends it's time, then
<UL>
<LI> rewrite the critical code, using a faster algorithm.
<LI> use the most recent compiler (2.95.2, I believe) which knows about more
recent Pentium-class processors.
<LI> compile the critical modules for speed, and the others for small size,
to make the image smaller.
<LI> if everything else fails, try rewriting critical sections an assembly code.
</UL>
<LI> kill all unnecessary services to give the program as much CPU time as
possible.
<LI> enhance the program's nice value (only root can do this, though).
<LI> make your program multi-processor-aware. Normal programs only use 1
CPU. You have to run several instances of your program (or make it
multi-threaded) to really take advantage of your two CPU's.
</UL>
<BLOCKQUOTE>
I've decided that the reason lies in the cache sped/size and bought
(pretty cheap) dual Pentium-II/450MHz Xeon computer with 2MB L2 cache
per proccessor that suppose to run at 450MHz and 512M SDRAM on
SuperMicro mainboard. Unfortunately I did not find any difference in
performance of this computer and still much cheaper dual
Pentium-II/400MHz. Why is it?
</BLOCKQUOTE>
<P> Total performance depends on a lot of things except CPU speed and cache
size. To name a few:
<UL>
<LI> amount of RAM
<LI> - type and speed of hard disks
<LI> - is the kernel SMP aware?
<LI> - number of processes competing for CPU time
</UL>
<P> The clock speeds between the two systems don't vary much. So if you find
that your performance hasn't increased as much as you expected, the only
thing that you can conclude is that the cache size probably isn't the limiting
factor here.
<BLOCKQUOTE>
May be, Red Nat 6.1 somehow must be told explicitely about cache size?
But I did not find any such option...
</BLOCKQUOTE>
<P> I don't *think* so. AFAIK, the cache can't be influenced from the OS on x86
CPU's. I've only heard of that trick with Mac's running on 68040's
<P> HTH, Roland
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: Anti Virus programs for linux Red Hat 6
</FONT> </H3>
Sun, 27 Feb 2000 15:35:41 +0100 (CET)
<BR>From: Roland Smith &lt;<A HREF="mailto:rsmith@xs4all.nl">rsmith@xs4all.nl&gt;</A>
<BLOCKQUOTE>
<P> Is there a "definative" anti virul program for Linux? Any info
appreciated!
</BLOCKQUOTE>
<P> There are several anti-virus programs available, see Freshmeat.net:
<A HREF="http://freshmeat.net/appindex/daemons/anti-virus.html">
http://freshmeat.net/appindex/daemons/anti-virus.html</A>
<P> I believe that the McAfee also runs on Linux.
<P> But these are mostly used for scanning mail destined for other systems that
are more vulnerable to viruses.
<P> Linux and other UNIX-like systems don't suffer much from viruses, because
most programs do not run with root privileges. So they don't have access to
the system, other than the user's home-directory and processes.
<P> So as long as you're surfing as a normal user, and not as root, any virus
that you contract can at most endanger your own files and processes, and
not the integrety of the system. Besides, most binary and macro viruses are
targeted on DOS/Windows, so they don't even work on Linux.
<P> Of course there are other attacks on your system possible, forms of
so-called root-exploits; using known defects in programs to gain access to
your machine as root.
<P> That's why you do need to keep track of your distribution's security
advisories.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: neighbour table overflow
</FONT> </H3>
Sun, 27 Feb 2000 15:38:13 +0100
<BR>From: Baco &lt;<A HREF="mailto:baco@baco.net">baco@baco.net&gt;</A>
<P> Dear,
<BLOCKQUOTE>
I was running quite a long time with NFS and transmission stopped. I
get: Sep 6 00:03:20 coyote kernel: eth0: trigger_send() called with
the transmitter busy. I rebooted the machine I was connected to and I
get the below (part of /var/log/messages >file. Not all error
statements shown):
<PRE>
Sep 6 17:57:04 beartooth kernel: neighbour table overflow
Sep 6 17:57:04 beartooth kernel: neighbour table overflow
Sep 6 17:57:04 beartooth rpc.statd: Cannot register service: RPC:
Unable to send; errno = No buffer space available
Sep 6 17:57:04 beartooth nfs: rpc.statd startup succeeded
Sep 6 17:57:04 beartooth rpc.statd[407]: unable to register (SM_PROG,
SM_VERS, udp).l:
</PRE>
</BLOCKQUOTE>
<P> I had the same problem but with all ftp daemons running
under inetd
<P> My problem was resolved when I added
"127.0.0.1 localhost" into /etc/hosts
and when I setup the loopback lo interface using route and ifconfig
<P> I hope this was also your problem.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Win95-Linux small network with null modem
</FONT> </H3>
Sun, 27 Feb 2000 10:36:57 -0500
<BR>From: David B Sarraf &lt;<A HREF="mailto:david.sarraf@juno.com">david.sarraf@juno.com&gt;</A>
<P> Dear Wagner Perlino
<P> What you are asking is commonly done with Linux. For example I have a
small home network with three and sometimes four W95 machines and
sometimes another Linux box. All are connected to a hub along with a
"server" linux box. That machine does the following
<UL>
<LI> dials my ISP on demand using the diald package
<LI> network address translation (masquerading) and firewalling (blocks
bad guys) using IPFWADM
<LI> intranet server using Apache
<LI> file (disk volume) and printer sharing (2 printers) using Samba
<LI> modem sharing (for Juno, FreeInet, etc)
<LI> intranet-enabled control of lamps and other devices using an X10
transmitter on the serial port.
</UL>
Projects underway:
<UL>
<LI> database server installation, possibly MySQL
<LI> cron and perl scripts to update a database of my personal Setiathome
statistics
</UL>
<P> I did not set out to do all of this at once. The project began as a
request to make a dial-on-demand connection. It just grew as I got
better with Linux and realized the power of the O/S and machine.
<P> Dial on demand was quite an experience to set up due to my then
inexperience with Linux, ISP hookups, and networking. Now it would be
quite easy.
<P> There were some issues with the current version of diald (0.16 and 0.99)
and incompatibilities with newer versions of Linux (particularly Red Hat
6.1 and the Ethertap device). When I did this project about a year ago
the issues were being worked through. Some comprehensive how-tos were
posted and some users were reporting success. By now the package itself
has probably been fixed. My workaround was to stay with diald 0.16 and
RedHat 5.1. Setup was straightforward and the combination has worked
flawlessly for about a year.
<P> Contact me if you want more details. I'd be glad to help.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Subject: insmod and newbie to RH6.1
</FONT> </H3>
Sun, 27 Feb 2000 11:05:53 -0500
<BR>From: David B Sarraf &lt;<A HREF="mailto:david.sarraf@juno.com">david.sarraf@juno.com&gt;</A>
<P> Put the insmod command into /etc/rc.d/rc.local
<P> Any commands there are run at boot time.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">secondary ide and cdrom
</FONT> </H3>
Sun, 27 Feb 2000 22:32:44 -0500
<BR>From: George W. Bursha &lt;<A HREF="mailto:gburs2@hotmail.com">gburs2@hotmail.com&gt;</A>
<P> I noticed a number of times people have problems with secondary ide on a
pnp sound card. Don't be alarmed by ide3: unexpected interrupt,
status=0xff, count=1. That is to say, if you are successful in getting
your isapnp.conf correct and the the card seems proper from dmesg all
except for this message and you still can't do a mount /dev/cdrom
/cd0.....well fool, then go to /dev and rm cdrom and ln -s to the
correct device! /dev/cdrom is probably linked to /dev/hdb for example.
When testing your cd use 'mount -t iso 9660 /dev/hdx /mnt/cdrom'. Where
x in hdx is the correct device name. You will perhaps surprise yourself
after many hours spent shaking your head.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: Users required to enter root-password? Red Hat 6.1
</FONT> </H3>
Tue, 29 Feb 2000 19:40:27 -0500
<BR>From: Srinivasa A. Shikaripura &lt;<A HREF="mailto:sas@lucent.com">sas@lucent.com&gt;</A>
<BLOCKQUOTE>
I have just installed version 6.1 and set up my modem to dial out to my ISP.
However, when I log on as a user and press KDE&gt;Internet&gt;kppp a pop-up box
opens up and wants me to enter the root-password! This does not seem right.
is there a way to avoid having to enter the root pass word when logged on
as a non-root user?
</BLOCKQUOTE>
<P> You could possibly change the permissions on /dev/modem and whatever
it is pointing to (/dev/ttyS1 etc.) to allow the user to read/write
from that device.
<P> You should also be selectively allow some users to use the modem by giving
group permissions, but I am really not suer how it is done. (but I know
it is possible).
<P> cheers
-Sas
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: Modem problem with 5.2
</FONT> </H3>
Sat, 04 Mar 2000 11:33:45 -0800
<BR>From: Steve Dunbar &lt;<A HREF="mailto:sad@efn.org">sad@efn.org&gt;</A>
<BLOCKQUOTE>
... I can hear the modem clicking like it is trying to dial, but it will never dial the number....
</BLOCKQUOTE>
<P> Try running setserial to set the IRQ used by the modem, e.g. I use
"setserial /dev/ttyS2 irq 5 uart 16550A" to get my modem working. This
command must be run as root. You may have to mess with the jumpers on
your modem card to set the IRQ.
<P> There should be an initialization script that controls serial port
configuration at boot time. On Suse 6.3 this is /sbin/init.d/serial. It
should be possible to edit this script to set your modem set up
automagically, although I haven't yet got it working on my system.
<P> See the Modem HOWTO for more info.
<P> -- Steve
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Installing Linux on a laptop with a single FD/CD slot
</FONT> </H3>
Sun, 5 Mar 2000 17:45:26 -0800
<BR>From: &lt;<A HREF="mailto:ben-fuzzybear@yahoo.com">ben-fuzzybear@yahoo.com&gt;</A>
<P> Saw this question in LG the other day - yep, I'm a few issues behind but
catching up fast. Relatively easy answer (I just tried it with both Debian and
Red Hat and it works fine):
<P> (Assumptions: you have DOS/Windows installed, and can read from your CD.)
<P> First, create a directory - C:\Linux is fine.
<P> (The two examples below will cover the majority of the installs done these days, and are easily adaptable to other distros.)
<H3>Debian</H3>
I'm one of those guys who'd never heard of a distro on CD until _after_
d'loading a gig-plus worth of stuff, back when... but somewhere on the CD there
should be files called "loadlin.exe", "root.bin", and "linux", ~1.5MB worth of
stuff. Copy those to your new directory. Shut down your machine (I'm assuming
the CD and the FD are not hot-swappable - otherwise there'd be no point to
this), swap in the CDR, and turn it back on. Start DOS - *not* a DOS window
under Win9x, but DOS (by pressing the F8 key, if necessary, as soon as you see
the "Starting Windows..." message), type
<PRE>
cd Linux
</PRE>
<P> at the C: prompt, then type
<PRE>
loadlin linux root=/dev/ram initrd=root.bin
</PRE>
<H3>Red Hat</H3>
<P> This uses the 5.2 CD but I would think it's much the same for the different
versions. From the "dosutils" directory, copy "loadlin.exe"; from
"dosutils\autoboot" copy "vmlinuz" and "initrd.img" into your "Linux"
directory. Shut down, attach CDROM, reboot into DOS, 'cd Linux', and type
<PRE>
loadlin vmlinuz initrd=initrd.img
</PRE>
<P> ...and you're on your way!
<P> Another tip, while we're on the subject - Debian has these files available at their FTP server, and probably on the CD as well -
<PRE>
base2_1.tgz - 10MB
drv1440.bin - 1.4MB
resc1440.bin - 1.4MB
</PRE>
<P> Stick these in your "Linux" directory, too; they'll install a base Linux
system on your HD, or let you perform any sort of rescue ops necessary (by
mounting your existing Linux partition as /target hanging off a ramdisk, for
example - forget your root password lately? <grin>). No CD required - that's
the entire base package. One of _the_ handiest things there is when you're
munging through a tricky installation - and a GOOD reference for the initial
state of your /etc files (look inside base2_1.tgz). Putting those files on the
DOS side is usually my first step during an installation, and it's saved my
sanity more than once.
<P> Ben Okopnik
Captain S/V "Ulysses"
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">X screen captures into video animation
</FONT> </H3>
Mon, 6 Mar 2000 10:27:37 -0700 (MST)
<BR>From: Michael J. Hammel &lt;<A HREF="mailto:mjhammel@graphics-muse.org">mjhammel@graphics-muse.org&gt;</A>
<P> Thus spoke Ferenc Tamas Gyurcsan
<BLOCKQUOTE>
I just saw your problem on the lg. Did you look for something like
xvidcap? (I can't give you an url, but you will find it.)
ps: If you manage to produce a good mpeg from the captured pictures,
please let me know how.
Ferenc
</BLOCKQUOTE>
<P> The original question was from Shawn Medero, who asked:
<BLOCKQUOTE>
It captures motion on the computer desktop, basically multiple
screen-captures tied together to form a movie of sorts. Primarly one would
use to create training demostrations on linux applications, etc.
</BLOCKQUOTE>
<P> I checked, and yes, XVidCap does appear to fit this description. A quick
check on <A HREF="http://freshmeat.net">Freshmeat</A> gave this description for
XVidCap:
<BLOCKQUOTE>
XVidCap is an X11/Xt program, which captures specified rectangular areas of
the X11 desktop. The captured frames can be saved in different formats
(XWD, PNG, JPEG, PPM). Frames per second and other parameters can be
defined at the command line. The saved frames could be used e.g. for an
mpeg encoder or to make an animated GIF. A Step-mode is supported to get a
frame on mouse click.
</BLOCKQUOTE>
<P> I tried to access the Homepage for this program, but couldn't get through,
though it might be a problem on my end. I don't have time to recheck
today, so I'll just pass along the URLs of interest.
<P> Download: <A HREF="ftp://ftp.komm.hdk-berlin.de/pub/linux/X11/">
ftp://ftp.komm.hdk-berlin.de/pub/linux/X11/</A>
Homepage: <A HREF="http://home.pages.de/~rasca/xvidcap/">
http://home.pages.de/~rasca/xvidcap/</A>
<P> Thanks to Ferenc for pointing this out. Its another application to add to
my own catalog of tools on the Graphics Muse site
(<A HREF="http://graphics-muse.com">http://graphics-muse.com</A>).
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Uninstalling Linux on a Laptop
</FONT> </H3>
Tue, 7 Mar 2000 12:55:23 -0500
<BR>From: &lt;<A HREF="mailto:Michael.Risser@Summus.com">Michael.Risser@Summus.com&gt;</A>
<P> First I know this is opposite of what the intentions of Linux are, but
sometimes it IS necessary.
I recently had to remove Linux from my Dell Inspiron 3500 Laptop so that I
could reinstall Windoze, it was necessary due to work, and limited
hard-drive space(4GB).
<P> Windows fdisk, Partition Magick, and Drive Wizard would not remove the
partitions I had created for Red Hat 6.1(kudos to Linux on that one :-))
Instead you must first begin installing WinNT, and allow it to remove the
partition. After WinNT has removed the partition you can either let it
format the drive, or install Windoze as normal. So far that is the only way
I have found to remove Linux partitions
<P> Note: This tip was actually given me by my brother-in-law who had to do the
same thing.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">2 Cent Tips
</FONT> </H3>
Wed, 08 Mar 2000 16:13:59 -0500
<BR>From: Bolen Coogler &lt;<A HREF="mailto:bcoogler@dscga.com">bcoogler@dscga.com&gt;</A>
How to set vi edit mode in bash for Mandrake 7.0
<P> If, like me, you prefer vi-style command line editing in bash, here's
how to get it working in Mandrake 7.0.
<P> When I wiped out Redhat 5.2 on my PC and installed Mandrake 7.0, I found
vi command line editing no longer worked, even after issuing the "set -o
vi" command. After much hair pulling and gnashing of teeth, I finally
found the problem is with the /etc/inputrc file. I still don't know
which line in this file
caused the problem. If you have this same problem in Mandrake or some
other distribution, my suggestion for a fix is:
<P> 1. su to root.
2. Save a copy of the original /etc/inputrc file (you may want it back).
<P> 3. Replace the contents of /etc/inputrc with the following:
<PRE>
set convert-meta off
set input-meta on
set output-meta on
set keymap vi
set editing-mode vi
</PRE>
<P> The next time you start a terminal session, vi editing will be
functional.
<P> --Bolen Coogler
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Solution to mysterious dial-in hangup
</FONT> </H3>
Wed, 15 Mar 2000 19:19:56 +0100
<BR>From: Eric Kaf&eacute; &lt;<A HREF="mailto:kafe@mobilixnet.dk">kafe@mobilixnet.dk&gt;</A>
<P> This seems to be a very common Red Hat 6.1 bug. The problem is
mentioned, without a solution, in the current FAQ for the PPP demon.
<P> After installing Red Hat 6.1, every time I tried to dial-in to my
ISP, a mysterious hangup occurred on the first attempt, and the
connection always succeeded the second time. I first suspected the
ISP, but they have nothing to do with it.
<P> The problem disappeared as soon as I compiled ppp from the most
recent source rpm. I use ppp-2.3.11-1 with a 2.2.14 kernel.
Compilation was straightforward. Now I connect at once and
everything is just fine.
<P> According to the README.linux file in the ppp documentation,
there are some subtleties related to compiling ppp for different
kernel versions. Perhaps the ppp package included in Red Hat 6.1
was configured for another kernel than it ships with.
<P> Best regards
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">ATI xpert cards
</FONT> </H3>
Sat, 18 Mar 2000 21:50:25 -0800
<BR>From: &lt;<A HREF="mailto:noah@nack.org">noah@nack.org&gt;</A>
<BLOCKQUOTE>
I'm new user and believer of the Linux OS and I need help badly. I'm looking for a driver for an ATI Xpert@Work 8Mb PCI card. Where can
I get it? I'm using a RedHat 5.2 and my monitor is a Mitsubishi Diamond Scan model FA3415AT4 [...]
</BLOCKQUOTE>
<P> Configure your display with the help of 'XF86Setup' (you have to write it as I do, with upper and lower cased letters), or, if it doesn't run the 'xf86config'
program. Try to find your ATI Card, and if you don't, use simply SVGA. Most of cards which are not listed are standard SVGA Cards (my Matrox
Millenium G200 also), and they run very well with the SVGA driver.
<P> I have (successfully) set up a bunch of ATI cards under RedHat, and lately
(&gt;=5.0) have found that Xconfigurator seems to give better results with ATI cards.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: Tip & Tricks
</FONT> </H3>
Tue, 21 Mar 2000 16:09:45 -0600
<BR>From: Jesse Lang &lt;<A HREF="mailto:jesse@tcmi.com">jesse@tcmi.com&gt;</A>
<P> The tip you're looking for looks something like this:
<P> Edit your dns entry that probably looks like this:
<PRE>
www A [Your Machine's IP Address]
</PRE>
TO:
<PRE>
@ A [Your Machine's IP Address]
www CNAME @
</PRE>
<P> What you're saying is that your IP is uniandes.edu.co and that www is a
alias to it. So either way, it will end up at your site. If Apache is set
up with the ServerName directive as "www.uniandes.edu.co", then it will fix
names as soon as it connects to apache.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Re: make virtuald
</FONT> </H3>
Tue, 21 Mar 2000 16:50:16 -0600
<BR>From: Jesse Lang &lt;<A HREF="mailto:jesse@tcmi.com">jesse@tcmi.com&gt;</A>
<P> Chances are if your are using any other platform than Linux (Windows, dos,
mac, etc.), the problem is the mode that ftp was in when you uploaded it.
You have to make sure you upload in ascii mode as opposed to binary. This
mode will do the proper conversion of line breaks and such. Give it another
shot. The best way to tell if it's readable on linux is to type 'cat
filename.c' You should see the line breaks in the right places. Hope
this works for you. Let me know if you need more help if this doesn't roll
out for you.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Linux not detecting above 64meg
</FONT> </H3>
Tue, 21 Mar 2000 16:50:16 -0600
<BR>From: Linux Gazette &lt;<A HREF="mailto:gazette@ssc.com">gazette@ssc.com&gt;</A>
<P> Several readers took your humble Editor to task for telling a user that
Linux cannot autodetect memory above 64 MB because of a BIOS limitation;
instead, I said that you have to tell Linux explicitly in the LILO config file
or at the LILO command line.
<P> The readers said they have had no problems with Linux autodetecting
their 128 MB of memory. So I went home and took the
<PRE>
append = "mem 128M"
</PRE>
line out of my /etc/lilo.conf file and discovered that, indeed, it was
unnecessary. But I know it was a necessity last year when I put the system
together. In the meantime I had switched from kernel 2.0.36 to 2.2.14--perhaps
autodetection was added to the 2.2 kernels.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Multiple video cards
</FONT> </H3>
Mon, 13 Mar 2000 12:46:32 +0100
<BR>From: Fran&ccedil;ois D&eacute;sarm&eacute;nien &lt;<A HREF="mailto:desar@club-internet.fr">desar@club-internet.fr</A>&gt;
<BLOCKQUOTE>
<P> I have a question, have you any idea where I could find info about running multiple video cards and monitors under linux. eg. 2 SVGA cards or a SVGA and a VGA card
... and how should one configure these ??
</BLOCKQUOTE>
<P> XFree4.0 (which is out now) should solve this issue.
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Screen "Camera" for linux
</FONT> </H3>
Thu, 30 Mar 2000 02:28:57 -0500
<BR>From: Paul Winkler &lt;<A HREF="mailto:slinkp23@yahoo.com">desar@club-internet.fr</A>&gt;
Shawn Medero wrote:
<BLOCKQUOTE>
It captures motion on the computer desktop . .basically multiple
screen-captures tied together to form a movie of sorts. Primarly
one would use to create training demostrations on linux applications, etc.
</BLOCKQUOTE>
<P> You could do this with import (part of the ImageMagick package) and
a simple shell script. Try this, for example.
<P> <A HREF="misc/tips/camera.sh.txt">camera.sh</A>
You could then combine them to an animated GIF with Gimp.
Or use ImageMagick's animate command to view the sequence, like
this:
<PRE>
animate shot*.gif
</PRE>
But that starts a loop that repeats until you stop it...
<P> <hr> <P>
<!--================================================================-->
<a name=""></a>
<H3><IMG ALIGN=BOTTOM ALT="" SRC="../gx/lil2cent.gif">
ANSWER: <FONT COLOR="navy">Extracting a block of text from a file
</FONT> </H3>
Thu, 30 Mar 2000 09:29:34 -0800
<BR>From: Jim Dennis &lt;<A HREF="mailto:jimd@linuxcare.com">djimd@linuxcare.com</A>&gt;
<BLOCKQUOTE>
I'm trying to extract a block of text from a file using just bash and
standard shell utilities (no perl, awk, sed, etc). I have a definitive
pattern that can denote the start and end or I can easily get the line
numbers that denote the start and end of the block of text I'm
interested in (which, by the way, I don't know ahead of time. I only
know where it is in the file). I can't find a utility or command that
will extract everything that falls between those points. Does such a
thing exist?
</BLOCKQUOTE>
<P> awk and sed are considered to be "standard shell utilities."
(They are part of the POSIX specification).
The sed expression is simply:
<PRE>
sed -n "$begin,${end}p" ...
</PRE>
... if begin and end are line numbers.
<P> For patterns it's easier to use awk:
<PRE>
awk "/$begin/,/$end/" ...
</PRE>
... Note: begin and end are regexes and should be
chosen carefully!
<P> However, since you don't want to do it the
easy way, here are some alternatives:
<P> ------------------ WARNING: very long -------------------------
<P> If it is a text file and you just want some lines out of
it try something like: (<A HREF="misc/tips/shextract.sh.txt">text version</A>)
<PRE>
#!/bin/sh
# shextract.sh
# extract part of a file between a
# pair of globbing patterns
[ "$#" -eq "2" ] || {
echo "Must supply begin and end patterns" &gt;&amp;2
exit 1
}
begin=$1
end=$2
of="" ## output flag
while read a; do
case "$a" in
"$begin") of="true";;
"$end") of="";;
esac
[ -n "$of" ] &amp;&amp; echo $a
done
exit 0
</PRE>
<P> ... this uses no external utilities except for the
test command ('[') and possibly the 'echo' command from
VERY old versions of Bourne sh. It should be supported
under any Bourne shell derivative. Under bash these
are builtin commands.
<P> It takes two parameters. These are "globbing" patterns
NOT regular expressions. They should be quoted, especially
if they contain shell wildcards (?, *, and [...]
expressions).
<P> Read any good shell programming reference (or even the
rather weak 'case...esac' section of the bash man page)
for details on the acceptable pattern syntax. Note
because of the way I'm using this you could invoke
this program (let's call it shextract, for "shell
extraction") like so:
<PRE>
shextract "[bB]egin|[Ss]tart" "[Ee]nd|[Ss]top"
</PRE>
<P> ... to extract the lines between the any occurrence
of the term "begin" or "Begin" or "start" or "Start" and
the any subsequent occurence of "end" or "End" or "stop"
or "Stop."
<P> Notice that I can use the (quoted) pipe symbol in this
context to show "alternation" (similar to the egrep use
of the same token).
<P> This script could be easily modified to use regex's
instead of glob patterns (though we'd either have to
use 'grep' for that or rely on a much newer shell
such as ksh '93 or bash v. 2.x to do so).
<P> This particular version will extract *all* regions
of the file that lie between our begin and end tokens.
<P> To stop after the first we have to insert a "break"
statement into our "$end") ...;;; case. To support
an "nth" occurence of the pattern we'd have to use
an additional argument. To cope with degenerate
input (cases where the begin and end tokens might be
out of order, nested or overlapped) we'd have to
do considerably more work.
<P> As written this example requires exactly two arguments.
It will only process input from stdin and only write
to stdout. We could easily add code to handle
more arguments (first two are patterns, 'shift'ed out
rest are input file names) and some options switches
(for output file, only one extraction per file,
emit errors if end pattern is found before start
pattern, emit warnings if no begin or subsequent end
pattern is found on any input file, stop processing on
any error/warning, etc).
<P> Note: my exit 0 may seem superfluous here. However,
it does prevent the shell from noting that the
program "exited with non-zero return value" or
warnings to that effect. That's due to my use of
test ('[') on my output flag in my loop. In the
normal case that will have left a non-zero return value
since my of flag will be zero length for the part of
the file AFTER the end pattern was found.
<P> Note: this program is SLOW. (That's what you get for
asking for it in sh). Running it on my 38,000 line
/usr/share/games/hangman-words (this laptop doesn't
have /usr/dict/words) it takes about 30 seconds or
roughly only 1000 lines per second on a P166 with 16Mb
of RAM. A binary can do better than that under MS-DOS
on a 4Mhz XT!
<P> BUG: If any lines begin with - (dashes) then your version
of echo *might* try to treat the beginnings of your lines
as arguments. This *might* cause the echo command to
parse the rest of the line for escape sequences. If you
have printf(1) evailable (as a built-in to your shell or
as an external command) then you might want to use that
instead of echo.
<P> To do this based on line numbers rather than patterns
we could use something more like:
(<A HREF="misc/tips/lnextract.sh.txt">text version</A>)
<PRE>
#!/bin/sh
# lnextract.sh
# extract part of a file between a
# line numbers $1 and $2
function isnum () {
case "$1" in
*[^0-9]*)
return 1;;
esac
}
[ "$#" -gt "2" ] || {
echo "Must supply begin and end line numbers" &gt;&amp;2
exit 1
}
isnum "$1" || {
echo "first argument (first line) must be a whole number" &gt;&amp;2
exit 1
}
isnum "$2" || {
echo "second argument (last line) must be a whole number" &gt;&amp;2
exit 1
}
begin=$1
end=$2
[ "$begin" -le "$end" ] || {
echo "begin must be less than or equal to end" &gt;&amp;2
exit 1
}
shift 2
for i; do
[ -r "$i" -a -f "$i" ] || {
echo "$i should be an existing regular file" &gt;&amp;2
continue
}
ln=0
while read a ; do
let ln+=1
[ "$ln" -ge "$begin" ] &amp;&amp; echo $a
[ "$ln" -lt "$end" ] || break
done < "$i"
done
exit 0
</PRE>
<P> This rather ugly little example does do quite a
bit more checking than my previous one.
<P> It checks that its first two arguments are
numbers (your shell must support negated character
class globs for this, ksh '88 and later, bash 1.x and 2.x,
and zsh all qualify), and that the first is less than or
equal to the latter. Then it shifts those out of
the way so it can iterate over the rest of the
arguments, extracting our interval of line from
each. It checks that each file is "regular"
(not a directory, socket, or device node) and
readable before it tries to extract a portion of
it. It will follow symlinks.
<P> It has some of the same limitations we saw before.
<P> In addition it won't accept it's input from stdin
(although we could add that by putting the main loop
into a shell function and invoking it one way if
our arg count was exactly two, and differently
(within our for loop) if $# is greater than two.
I don't feel like doing that here --- as this message
is already way too long and that example is complicated
enough.
<P> It's also possible to use a combination of 'head' and
'tail' to do this. (That's a common exercise in
shell programming classes). You just use something
like:
<PRE>
head -$end $file | tail -$(( $end - $begin ))
</PRE>
<P> ... note that the 'tail' command on many versions
of UNIX can't handle arbitrary offsets. It can
only handle the lines that fit into a fixed block size.
GNU tail is somewhat more robust (and correspondingly
larger and more complicated). A classic way to
work around limitations on tail was to use tac (cat
a file backwards, from last line to first) and
head (and tac again). This might use prodigous
amounts of memory or disk space (might use temporary
files).
<P> If you don't want line oriented output --- and your
patterns are regular expressions, and you're willing
to use grep and dd then here's a different approach:
<PRE>
start=$(grep -b "$begin" ... )
stop=$(( $( grep -b "$end" ... ) - $begin ))
dd if="$file" skip=$begin count=$stop bs=1b
</PRE>
<P> This is not a shell script, just an example.
Obviously you'd have to initialize $begin, $end, and $file
or use $1, $2, and $3 for them to make this into a
script. Also you have to modify those grep -b commands
a little bit (note my ellipses). This is because grep
will be giving us too much information. It will be
giving a byte offset to the beginning of each pattern
match, and it will be printing the matching line, too.
<P> We can fix this with a little work. Let's assume that
we want the first occurrence of "$begin" and the last
occurence of "$end" Here's the commands that will
just give us the raw numbers:
<PRE>
grep -b "$begin" "$file" | head -1 {
IFS=:
read b x
echo b
}
grep -b "$end" "$file" | tail -1 | {
IFS=:
read e x
echo e
}
</PRE>
<P> ... notice I just grep through head or
tail to get the first or last matching line,
and I use IFS to change my field separator
to a ":" (which grep uses to separate the offset
value from the rest of the line). I read the
line into two variables (separated by the
IFS character(s)), and throw away the extraneous
data by simply echoing the part I wanted
(the byte offset) back out of my subshell.
<P> Note: whenever you use or see a pipe operator
in a shell command or script --- you should
realize that you've created an implicit subshell
to handle that.
<P> Incidentally, if your patterns *might* have a
leading - (dash) then you'll have problems
passing them to grep. You can massage the
pattern a little bit by wrapping the first
character with square brackets. Thus "foo"
becomes "[f]oo" and "-bar" becomes "[-]bar".
(grep won't consider an argument starting
with [ to be a command line switch, but it
will try to parse -bar as one).
<P> This is easily done with printf and sed:
<PRE>
printf "%s" "$pattern" | sed -e 's/./[&amp;]/'
</PRE>
<P> ... note my previous warning about 'echo' ---
it's pretty permissive about arguments that
start with dashes that it doesn't recognize, it'll
just echo those without error. But if your pattern
starts with "-e " or -n it can effect out the rest
of the string is represented.
<P> Note that GNU grep and echo DON'T seem to take the
-- option that is included with some GNU utilities.
This would avoid the whole issue of leading dashes
since this conventionally marks the end of all
switch/option parsing for them.
<P> Of course you said you didn't want to use sed,
so you've made the job harder. Not impossible,
but harder. With newer shells like ksh '93 and
bash 2.x we can use something like:
<PRE>
[${pattern:0:1}]${pattern:1}
</PRE>
<P> (read any recent good book on shell programming
to learn about parameter expansion).
You<P> can use the old 'cut' utility, or 'dd' to
get these substrings. Of course those are just
as external to the shell as perl, awk, sed,
test, expr and printf.
If you<P> really wanted to do this last sort of
thing (getting a specific size substring from
a variable's value, starting from an offset
in the string, using only the bash 1.x parameter
expansion primitives) it could be done with a whole
lot of fussing. I'd use ${#varname} to get the
size, a loop to build temporary strings of
? (question mark) characters to of the right
length and the ${foo#} and ${foo%} operators
(stripping patterns from the left and right of
variable's value respectively)
to isolate my substring.
<P> Yuck! That really is as ugly as it sounds.
<P> Anyway. I think I've said enough on the subject
for now.
<P> I'm sure you can do what you need to. Alot of
it depends on which shell you're using (not just
csh vs. Bourne, but ksh '88 vs. '93 and bash v1.14
vs. 2.x, etc) and just how rigit you are about that
constraint about "standard utilities"
<P> All of the examples here (except for the ${foo:}
parameter expansion) are compatible with bash 1.14.
<P> (BTW: now that I'm really learning C --- y'all can
either rest easy that I'll be laying off the sh
syntax for awhile, or lay awake in fear of what I'll
be writing about next month).
<P> Here's a short GNU C program to print a set of
lines between one number and another:
(<A HREF="cextract.c.txt">text version</A>)
<PRE>
/* extract a portion of a file from some beginning line, to
* some ending line
* this functions as a filter --- it doesn't take a list
* of file name arguments.
*/
#include &amp;lt;stdio.h&amp;gt;
#include &amp;lt;stdlib.h&amp;gt;
#include &amp;lt;errno.h&amp;gt;
int
main (int argc, char * argv[] )
{
char * linestr;
long begin, end, current=0;
ssize_t * linelen;
linelen = 0;
linestr=NULL;
if ( argc &amp;lt; 3 ) {
fprintf(stderr, "Usage: %s begin end\n", argv[0]);
exit(1);
}
begin=atol(argv[1]);
if ( begin &amp;lt; 1 ) {
fprintf(stderr, "Argument error: %s should be a number "
"greater than zero\n", argv[1]);
exit(1);
}
end=atol(argv[2]);
if ( end &amp;lt; begin ) {
fprintf(stderr, "Argument error: %s should be a number "
"greater than arg[1]\n", argv[1]);
exit(1);
}
while ( getline(&amp;linestr, &amp;linelen, stdin ) &amp;gt; -1
&amp;&amp; (++current &amp;lt; end ) ) {
if (current &amp;gt;= begin) {
printf("%s", linestr);
}
}
exit(0);
return 0;
}
</PRE>
<P> This is about the same length as my shell version.
It uses atol() rather than strtol() for the
argument to number conversion. atol() (ASCII to long)
is simpler, but can't convey errors back to us.
However, I require values greater than zero, and GNU
glibc atol() returns 0 for strings that can't be
converted to longs. I also use the GNU getline()
function --- which is non-standard, but much more
convenient and robust than fussing with scanf(),
fgets() and sscanf(), and getc() stuff.
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