Saving Space mini-HOWTO
By Guido Gonzato, <mailto:guido@ibogeo.df.unibo.it>
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,
<REMOVE_MEguido@ibogeo.df.unibo.it>.
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-)
