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<!--startcut ==========================================================-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<title>Linux on a Shoestring LG #36</title>
  <meta name="summary" content="How to run Linux on an antiquated machine">
</HEAD>
<BODY BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#A000A0"
ALINK="#FF0000">
<!--endcut ============================================================-->

<H4>
"Linux Gazette...<I>making Linux just a little more fun!</I>"
</H4>

<P> <HR> <P> 
<!--===================================================================-->

<center>
<H1><font color="maroon">Linux on a Shoestring</font></H1>
<H4>By <a href="mailto:csu96177@cse.iitd.ernet.in">Vivek Haldar</a></H4>
</center>
<P> <HR> <P>  

This article first appeared in the September 1998 issue of PC Quest, India's
leading infotech magazine.
<P> <HR> <P> 

<!-- AS-TOC_BEGIN{ -->
<H1 ALIGN=center>Table of Contents</H1>

<UL>
	<LI><A HREF="#as-h2-23100">INTRODUCTION</A>
	<LI><A HREF="#as-h2-23101">SAVE RAM!</A>
	<UL>
		<LI><A HREF="#as-h3-23102">RECOMPILE THE KERNEL</A>
		<LI><A HREF="#as-h3-23103">STOP SOME SERVICES!</A>
		<LI><A HREF="#as-h3-23104">HOW TO REMOVE SERVICES FROM A RUNLEVEL </A>
		<LI><A HREF="#as-h3-23105">WHICH SERVICES TO KEEP, AND WHICH TO REMOVE </A>
		<LI><A HREF="#as-h3-23106">SERVICES YOU MIGHT WANT TO KEEP</A>
	</UL>
	<LI><A HREF="#as-h2-23107">SAVE DISK SPACE</A>
	<UL>
		<LI><A HREF="#as-h3-23108">HOW TO REMOVE A PACKAGE </A>
		<LI><A HREF="#as-h3-23109">WHICH PACKAGES DO I REMOVE?</A>
	</UL>
	<LI><A HREF="#as-h2-231010">WINDING UP</A>
</UL>
<!-- AS-TOC_END} -->


<HR>




<H2><A NAME="as-h2-23100">INTRODUCTION</A></H2>

	
<P>

      With every operating system out there screaming "Give me more!"
      - more disk space, more RAM, more Mhz - it's comforting to know
        that there is one savior out there for those of us not
        endowed with the sizzlingly latest hardware. Yes, I am talking 
        about Linux.
      
<P>
Though Linux shines as a network operating system, and is often
      projected as one, the fact is that it makes a great single user
      OS as well - something that one could use on a non-networked
      home PC. 
<P>
And in that case, there are a number of ways in which you could
      tweak your system to get more punch out of it - even on machines
      as antiquated as 486s, and with as little RAM as 8MB.

         
<P>
Now please remember that you need to be logged in as root to do
      all the following things. Our attack will be two pronged - to
      minimize usage of RAM, and to save disk space. 

  <H2><A NAME="as-h2-23101">SAVE RAM!</A></H2>


  <H3><A NAME="as-h3-23102">RECOMPILE THE KERNEL</A></H3>

           
<P>
 The kernel that is installed out of the box does the job,
            but its a catch-all kernel, with almost everything
            compiled into it. Which means that its bigger than it has
            to be for you. If you compile your own kernel from the
            kernel sources, it could be upto 100kb smaller than the
            default vmlinuz kernel. Besides, its very helpful to know
            how to compile the kernel. 
            It's quite simple actually. You first configure it, that
            is, you say what all you want in your kernel. And then you 
            compile it. 
           
<P>
 Linux has reached that advanced stage in its evolution
            where even the kernel configuration can be done
            graphically. The kernel sources usually reside in
            /usr/src/linux. To get the graphical configuration
            running, do "make menuconfig"(for text based menus), or "make 
            xconfig"(for graphical setup in X). You'll be presented
            with a long list of configurable options, and before
            deciding, it is advisable to see the sagely help note
            which goes along with each. The notes always give sound
            advice, and you should follow it. By doing so, you'll land
            up with exactly the things that you need compiled into
            your kernel, and nothing else. I would also suggest
            reading the README file in the source directory. 
            Once you've configured everything, quit X if you're
            running it. This is so that you can do the compilation in
            text mode, without a heavy X running, and with more
            available RAM. 
           
<P>
 Do "make dep; make zImage", go have coffee, and come back
            after some time. Once that is done, the README explains in
            no uncertain terms what to do with your new kernel, and I
            would only be reproducing it if I told you.

         <H3><A NAME="as-h3-23103">STOP SOME SERVICES!</A></H3>

            
<P>
When a normal Linux system is running, there are a number of
            background jobs constantly running on it, each for a specific 
            purpose - these are called <EM>daemons</EM>. For example, sendmail,
            the mail daemon, is the process which takes care of all the
            sending and routing of mail. A number of such daemons are
            started at bootup. And to group together sets of daemons that 
            you might want to start for specific purposes, you have
            <EM>runlevels</EM>, which are simply groupings of services to start
            and stop. For example, on a normal Linux system runlevel 1,
            which is single user mode, will obviously need a lot fewer
            services to be running than runlevel 3, the full fledged
            multi user mode. 
            
<P>

Linux, by default, boots into <STRONG>runlevel 3</STRONG>. Now it turns out
            that of the myriad services started in that runlevel, some of 
            them a simple non networked home PC could do without. For
            example, you obviously wouldn't want to waste precious RAM by 
            running sendmail on such a machine. Yeah, it can be fun to
            send mail back and forth between root@localhost, and
            someuser@localhost, but that wears off pretty fast. 

  <H3><A NAME="as-h3-23104">HOW TO REMOVE SERVICES FROM A RUNLEVEL </A></H3>

               
<P>
With RedHat, it's all very simple. Administration is
               definitely one of the areas in which RedHat scores over
               other distributions. After logging in as root, start X,
               and from an xterm, start "tksysv". This is the graphical
               runlevel editor.  
               
<P>

You'll see six columns, one for each runlevel. Now we'll
               only be fiddling with runlevel 3, the one which Linux
               normally boots into. Each column will have two halves, the
               top one for services to start at bootup, and the botton
               one for services to stop at shutdown. All you have to do
               to remove a particular service is to select it, and press
               Del. Thats it. Just remember to save your changes before
               quitting. 

<H3><A NAME="as-h3-23105"> WHICH SERVICES TO KEEP, AND WHICH TO REMOVE </A></H3>

               
<P>
Actually, it's much simpler to tell you which ones to
               keep. Remember, all this tweaking is only in runlevel
               3. Now the bare essentials are :
               <UL>
               <LI><STRONG>kerneld</STRONG> - nothing will work without this!
               <LI><STRONG>syslog </STRONG>- must have around for kernel to log
               messages. The logs are helpful for seeing what was
               going on with your system in case something goes
               wrong(actually, nothing ever goes wrong with Linux!).
               <LI> <STRONG>keytable</STRONG> - you need this if want to be able to use
               your keyboard!
               <LI><STRONG>rc.local</STRONG> - this is where some trivial nitty gritties
               happen, after all the other services have been
               started. 
</UL>

               
               
<P>
You simply need to have the above four
               services. Without them, as some say, "not everything
               will work."
  <H3><A NAME="as-h3-23106">SERVICES YOU MIGHT WANT TO KEEP</A></H3>

              
<P>
 Then there are the fence sitters - non critical services
               which you might want to keep, if you need them, or if
               you fancy them.
               <UL>
               <LI> <STRONG>crond </STRONG>- this runs a number of trivial jobs
               periodically, the most important of which is to make
               sure that your log files don't get too large. you can
               run it if you're paranoid. 
               <LI><STRONG>atd</STRONG> - this deamon is required if you want to run "at" 
               jobs, i.e., jobs which begin execution at a time
               specified by you. people working on large, multi-user
               systems which are up 24 hours, everyday, use this to run
               heavy computational jobs at night, when loads on the
               system are lighter. but on a simple home machine, i
               don't see much use for it. after all, you're the only
               one using it!
               <LI> <STRONG>gpm</STRONG> - this allows you to use the mouse in text
               mode. useful sometimes only if you work in text mode,
               and a complete waste if you work in x. 
</UL>
 
               

<H2><A NAME="as-h2-23107"> SAVE DISK SPACE</A></H2>

      
<P>
   Actually, there's nothing much you can do here, except
         removing unwanted packages. Redhat linux has a superb,
         easy to use, and comprehensive package management system 
         which can keep track of almost every non user file on
         your disk. Everything installed on your system is part
         of some package, and packeges can be uninstalled. 

<H3><A NAME="as-h3-23108"> HOW TO REMOVE A PACKAGE </A></H3>


          
<P>
  Just run "glint", the graphical interface to the
            redhat package management system, from a command line
            while in x, and you will get a graphical interface to
            all the packages installed on your system. The
            packages are classified, and show up in a directory
            browser like window. To remove a package, just select
            it and click on the "uninstall" button on the right
            side.
            
<H3><A NAME="as-h3-23109">  WHICH PACKAGES DO I REMOVE?</A></H3>

            
<P>
Beware though, there are some critical packages which
            shouldn't be uninstalled. In glint, it's generally
            advisable to not touch the "base" and "library"
            packages unless you know exactly what you are
            doing. 
            
<P>

            For others, see their description(click the "query"
            button). If you haven't used that package in a long
            time, or don't foresee using it, it's generally safe
            to remove it. In case removing a package affects any
            other package, glint will tell you. It's all quite
            safe. If you do end up needing the package, you can
            always reinstall it from the CD.
            
<H2><A NAME="as-h2-231010">  WINDING UP</A></H2>


<P>
      These were only a few suggestions that you could try
      out. The more comfortable you get with Linux, and the more
      you explore, the more ideas you'll get to tweak your system 
      to get the most out of it. 

<P>
      <EM>Linux is an OS which is more
      forgiving to experimentation than most others. So think,
      and try it out!</EM>


<!--===================================================================-->
<P> <hr> <P> 
<center><H5>Copyright &copy; 1999, Vivek Haldar <BR> 
Published in Issue 36 of <i>Linux Gazette</i>, January 1999</H5></center>

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