Saving Space mini-HOWTO
 By Guido Gonzato,  <mailto:[email protected]>
 v1.0.1, 7 April 1999

 This mini-HOWTO gives you directions for squeezing your Linux instal
 lation into the least possible space. It's particularly aimed at note
 book users.
 ______________________________________________________________________

 Table of Contents


 1. Introduction

 2. Software requirements

 3. The procedure

    3.1 Removing the Kernel Sources
    3.2 Pruning Out Applications
    3.3 Stripping Binaries
    3.4 Compressing with
    3.5 Gzipping around

 4. A Real Life Example

 5. The End

    5.1 Copyright
    5.2 Disclaimer


 ______________________________________________________________________

 1.  Introduction


 I've got a notebook I installed Linux on, beside Windows 95 that was
 pre--installed. I squeezed the Windows partition to 500 Mb, making
 space for a 240 Mb Linux one. Small though the latter may seem, I've
 managed to install a fairly complete Linux system on it, based on Red
 Hat 4.1 and some magic to save as much space as possible.

 If you're in need for space, the indications you'll find in the
 following sections will free up a considerable chunk of hard disk. The
 only caveat I'm giving you is: don't blame me if something goes wrong!
 We'll be using a couple of programs that worked fine for me, but are
 inherently dangerous.  You've been warned.

 2.  Software requirements


 You need:


   a fully working Linux system (any version should be OK);

   the common gzip compression utility, or alternatively bzip2 that
    you find on <ftp://sunsite.unc.edu:/pub/Linux/utils/compress>; this
    tool compresses better than gzip, but it's also a wee bit slower
    and consumes a lot of memory;

   the upx executable compressor, whose home page is at
    <http://cdata.tvnet.hu/~ml/upx.html> and <http://wildsau.idv.uni-
    linz.ac.at/mfx/upx.html>;

   the zlibc package, available on
    <ftp://sunsite.unc.edu:/pub/Linux/libs/compression>. It's called
    zlibc-X.X.tar.gz, where X.X is the latest version.

 There are other executable compressors. One is gzexe (forget it),
 while tcx was probably the best before upx became available; yet
 another is tzx, in theory better than tcx. The thing is, it screwed
 everything up when I tried it on a spare PC, though I'm not sure if I
 did something wrong. You had better stick with upx: it's reliable,
 efficient, and very handy.

 There are kernel patches that provide transparent file system
 compression a la Stacker, but as of this writing none of them has yet
 a reputation for stability and reliability. For safety's sake, steer
 clear.

 3.  The procedure

 3.1.  Removing the Kernel Sources


 The kernel sources take up more than 20 Mb, and you may want to remove
 them.  If so, I suggest that you compile a new kernel that is tailored
 to your machine once and for all, then get rid of the sources. Take
 care, though.

 I don't recommend that you remove the kernel sources unless you are
 sure that your machine is properly configured. Besides, you need the
 kernel #includes to compile C programs. Think twice!

 If you do decide so, do not remove the include/linux tree unless you
 know you'll never compile applications on your machine.

 3.2.  Pruning Out Applications


 Now, decide which applications you really need. Some may prove
 redundant: for instance, are you sure you can't live without emacs?
 You could use jed instead.

 It's up to you to decide what you want to keep. Some general points:


   gcc is a fairly large package. It's needed to recompile the kernel
    and all the applications for which there are no pre--built Linux
    binaries. It's also needed, of course, if you write your own C or
    Fortran (with f2c or g77) programs; consider your needs before
    removing it.  Other compilers like lcc are fine, but not up to gcc
    level. I suggest that you keep it;

   X11 is awfully large, but it's a nice thing to have. If you decide
    you can't give it up, at least try to make do with as little as
    necessary: only the right X server, one simple window manager, only
    one xterm, no 100 dpi fonts, and so on;

   TeX and accompanying packages are very large indeed. Giving up
    LaTeX and sticking to plain TeX saves a lot of space; giving up X11
    previewers like xdvi and ghostview is possible if you use dvitty,
    dvivga and some such. Eliminating the need for X11 dviware could
    even make X11 redundant;

   games are never ``necessary''.

 3.3.  Stripping Binaries


 Let's start reducing the size of binaries. Move to /usr/bin and issue
 the command

      machine:/usr/bin# strip *

 which will do away with symbols embedded in binaries. Repeat this step
 in /usr/X11R6/bin/ and other directories containing executables you
 may have (don't forget to locate TeX's and gcc's binaries), but do not
 run it under /sbin, /bin, or /usr/sbin/ if you value your
 installation!

 3.4.  Compressing with upx


 First, install upx and read its documentation. Then go to /usr/bin and
 run it with the command upx *; it will compress all executables,
 including suid ones (tcx wouldn't). Repeat this step in other
 directories as seen above.

 Remember to compress the executables whenever you install a new
 package!

 3.5.  Gzipping around


 There are lots of other files that can be compressed once and for all.
 Let's start with /usr/doc/; move to this directory and issue the
 command

      machine:/usr/doc# find . -type f -exec gzip -9 {} \; 2> /dev/null

 Remember to compress the docs whenever you install a new package!

 Repeat this step in the directory containing the documentation for TeX
 (on my system, /usr/lib/texmf/texmf/doc/. If you're really sure,
 remove these directories altogether.

 Now, install zlibc and compile it. If your system is like mine, the
 compilation process will abort complaining about a missing (static)
 libc.  Never mind; you'll find a file called uncompress.o that is
 what's needed. Move it to /usr/local/lib/ and add this line to your
 /etc/profile:

      export LD_ELF_PRELOAD=/usr/local/lib/uncompress.o

 Now, you can compress with gzip not only documentation, but also data
 files: the applications that use them will be able to use them
 nonetheless.  In theory, the trick should work with most applications,
 but in practice your degree of success may vary. Mine was rather
 unimpressive.

 4.  A Real Life Example


 This is what I got applying the above procedure to one of my machines.
 Before the treatment, df reported I used 398,798 1024--blocks:


   I didn't remove the kernel sources and the kernel headers;

   I uninstalled several applications and all of the games, but I left
    X11, X11 development, C and Fortran development, Tcl/Tk, networking
    tools, and a few other standard applications. df reported 244,668
    used blocks;

   I ran upx on /usr/bin, /usr/X11R6/bin,
    /usr/lib/texmf/bin/i586-linux, and /usr/lib/gcc-
    lib/i386-linux/2.7.2.1. 226,270 used blocks;

   I compressed the documentation under /usr/doc and
    /usr/lib/texmf/texmf/doc: 198,745 used blocks.

 To sum up, I started with 398,798 blocks and finished with 198,745.
 Think of the stuff you can shove in those 200,000 spared blocks! I
 would have saved even more if I had used bzip2 instead of gzip.

 On average, if you are careful from the beginning and install only the
 necessary applications, compressing executables and documents will
 save you some 20 Mb. On a notebook, this can be a lifesaver.

 5.  The End

 5.1.  Copyright


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 5.2.  Disclaimer


 ``Saving Space mini-HOWTO''was written by Guido Gonzato,
 <[email protected]>.

 This document is provided ``as is''. I put great effort into writing
 it as accurately as I could, but you use the information contained in
 it at your own risk. In no event shall I be liable for any damages
 resulting from the use of this work.

 Feedback is welcome. For any requests, suggestions, flames, etc., feel
 free to contact me.

 Enjoy Linux and life,

 Guido   =8-)

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