muLinux (µ-Linux) is a full-configured, minimalistic, almost complete, application-centric tiny distribution of Linux made in Italy, fitted on a single 1722K floppy.
Its aim is to demonstrate the power and scalability of this operating system.
The 2.0.36 kernel is compiled for the 386 (without co-processor) and modularized
as much as possible. The binaries are taken from the dozens of distibutions and
boot-floppies on my 3 big hard-disks. Are you wondering why I chose a particular
binary, When I had two of them with the same name? I simply took the smallest
and the one which needs only
libc.so.5. I won't bother you telling
about all the dirty hacks to save space: it's enough for you to know that I
rewrote in C the
expr command, because I couldn't understand why it
takes 50328 bytes when I can do the same job with only 4586 bytes. I even
sed and other similar stuff.
muLinux is not intended for the generic mouse-based user, who wouldn't be
very Happy with its spartan interface, but for the Linux fan in general, or the
curious person who wants to look inside scripts to understand why an hack as
sendmail (only 1216 bytes) is really able to deliver mail
with the correct return-address. Moreover, a portable Linux would be ideal in a
number of situations: maintenance in different places, as a demonstration, as
embeddable system or just to see it booting at times, for no particular reason.
Most PC hardware will work fine. The very minimum is a 386 with 8MB of RAM:
installing muLinux with only 4MB is russian roulette. A math coprocessor is
NOT required since
mulinuz has math emulation built in.
A hard-disk in not required. Of course, you can mount the existing partitions on your hard-disks if you want. SCSI disks are not directly supported because of the huge variety of controller cards. If you want SCSI support please read How can I personalize muLinux?
In order to configure and control all resources , muLinux has a script
setup, see setup -h ) which is able to read (
-r) and write (
setup -s) muLinux profiles to and from the
floppy, the type of keyboard, ethernet data, where the mouse and modem are
located, which modules the kernel has to load at each boot, the phone number of
your ISP, and so on. Thank God, you only have to bother with this profile the
first time you boot the floppy. The user, however, is able to type a command
setup -f ppp or
setup -f net each time he wants
-f means "force"). Or, if you want, you can type
-a means "all". In order to use the floppy in
various positions, the
setup command manages a sort of
"multi-configuration". You are able to switch from one profile to another one
whenever you want. You can save different profiles with different names. For
setup -r "home" you can load a profile with only ppp
setup -r "pc12" you can load a profile for an
ethernet card and the IP for PC #12. All this stuff resides in the
/init directory of the BOOT segment, while the current profile
When muLinux boot, setup ask you for a profile to load. Special config name are "NONE" and "lock": with NONE, setup skip any operation and if your last saved config is named "lock", setup load them without confirm.
setup command, you can also load in memory a compressed
modules: setup -m module_name and, starting from 10r0 release, it support also
command line mode. See help.
Starting from version 2.0, muLinux is able to install itself not only in RAM, but permanently into a DOS directory (UMSDOS installation) or into a free partion of your hard-disk (EXT2 installations). You only need about 8-10M of free space somewhere on your hard-disk.
To perform this kind of installation, the muLinux kernel comes with
DOS support, and we added
loadlin.exe to the floppy. In both cases, we use
loadlin to boot muLinux, so it is necessary to start from the DOS
prompt with the command
linux.bat. The reason behind this choice is
that muLinux was built to be used temporarly on PCs which we do not own: we must
perform non-invasive and easily removable installations.
UMSDOS installation realizes this concept: you can share disk
space between Linux and DOS; you do not have to repartition hard-disks and you
can remove it without particular effort.
EXT2 installation, on the contrary, is just a curiosity and it
is the only intrinsecally dangerous one: muLinux will have to format the chosen
partition (like every Linux installation floppy) and it is possible For a novice
user to chose the wrong partition. By the way, if you really have a spare
partition sufficiently big, why don't you install a true Linux?
Release > 5.1 support also another kind of DOS-based installation: the
loop filesystem. This feature uses the so-called "loop Linux
device", a whole filesystem embedded in a normal DOS file, located in c:\linux.
At this point you will be asking about the title of this section. Actually,
what we described until now are not real installations but actually a cloning
process. The entire muLinux filesystem (even mounted devices) is copied (with
cp -a, that's true!) into the chosen destination.
Just a few word of advice: do not leave your cd-rom or any NFS volume mounted while cloning mulinux if you do not want the entire universe being replicated into your DOS partition!
Cloned muLinux systems work just as normal systems mounted in RAM. Setup and autoconfiguration procedures are consistent between the three installation modalities. The user will not notice any difference. This feature makes muLinux different from similar floppy-Linux offerings, which have a stronger link with the floppy.
Starting from 7r4 release, a new kind of cloning (via /bin/roclone) is provided. This is primarily for to embed a frozen copy of active filesystem in a (maybe read-only, bootable) media, with DOS campatible formatting. Usefull for clone on Iomega ZIP, CD-R (El-Torrito mechanism) and other removable media (SCSI devices supported).
From a technical point of view, all happen in usually way, but after booting
muLinux try to mount own USR segment from a removable device, probing in turn
CDROM IDE, CDROM Scsi, ZIP floppy and other. If succeded, muLinux mount the USR
image (a normal file in the boot/ directory) using the
Linux device and uses a mixed filesystem arrangement: RAMDISKs and read-only
EXT addon mounted is required, for this functionality. Tested on IOMEGA Zip and HP CD-Writer M820 devices by myself.
The cloning process (see muLinux and
the sheep Dolly), which can be run by the user with the
command at any time, will automatically start when the system recognizes that
there is insufficient RAM available (<4M).
In this case, muLinux stays at "runlevel 3" (only the
commands available), immediately creates a swap file in the DOS partition, and
starts cloning itself without delay.
When you see the message
Automatic reboot in progress, extract
the floppy and start DOS. At the dos prompt cd into
linux.bat: the cloned muLinux will soon be up and running.
The first boot of this new system is exhausting like the pains of a
childbirth: if muLinux realizes that some components are missing (typically
X11), it starts copying them from floppy to
HD. If instead you manually cloned muLinux starting from a RAM-mounted system
already configured, the cloned system will already be complete.
Beware that on a 386 with 4M the entire cloning process and "re-animation" can take more than 15 minutes the very first time, but you will then be able to see XWindow starting on your 386!
Starting from version 3.0, code-name "Hammameth", muLinux is able to install its root filesystem via NFS (Network File System), provided you have a working LAN-server supporting this traditional TCP/IP protocol.
The nfsroot-service is configured with the usual setup procedure (see The setup command): muLinux will ask to configure the Ethernet parameters and to specify the nfs_root, i.e. the remote directory containing a Linux system (which can also be a copy of muLinux).
muLinux kernel was slightly modified in order to mount the "real root" only after the configuration of the variuos network drivers: muLinux kernel is modular, so it is not possible to configure these drivers via the usual boot parameters (nfsroot= and nfsaddrs=). The patch is so tiny (just one line) that it can be the subject of an email or it can be written on a stamp!
For example, suppose your muLinux clients have IP addresses given by (in dot-notation) 192.168.1.x, and that the nfs_root is /remote/root. The /etc/exports on the server could be something like
#/etc/exports /remote/root 192.168.1.0/255.255.255.0(rw,no_root_squash)
Once you saved the profile on the floppy (with your favourite name, for example "nfs"), the next time muLinux is booted you only have to request this "nfs" profile: muLinux will configure the network drivers and mount the nfs_root.
If the remote system is itself a muLinux system, it is possible that at the first boot the "remote" muLinux will ask you to restart the setup one more time. Forgive him: how can he know that you already answered all those questions?
In order to prepare the remote system it is enough copying the entire muLinux tree into the server's /remote/root. Another solution is exporting the entire server's root (THIS SOLUTION IS NOT SAFE).
If you have a spare EXT2 partition on the server (/dev/hdb1 for instance), you can also prepare it with a working Linux distribution and export it to the workstations. In this case it is enough to mount this partition at boot time (place the line "mount -t ext2 /dev/hdb1 /remote/root" into one of the server's boot scripts) in order to make it available to the clients. The clients' /etc/fstab should contain something like
/dev/nfs / ext2 defaults 1 1
If the client needs swap space, it must use a local disk: muLinux kernel is not able (at this time) to swap via NFS.
For machines with low memory (less than 4M of ram), the boot process is slightly changed: muLinux will immediately ask if you want to clone the system to disk (like previous versions), or if you want to mount root via NFS. With little effort it is possible to transform your 386 into a diskless workstation based on Linux+XWindow. This solution is very cheap and efficient for many schools with obsolete computer labs (like many Technical Institues you can find in Italy).
______________________________ __|__ ___|___ | | local network | | ______ PPP-link to provider | PC | 192.168.1.0 | Linux |--|modem |------------------> | | | Router| |______| x.x.x.x |_____| |_______| (dynamic IP-address) pppd
IP filtering firewall is designed to control the flow of packets based the
source, destination, port and packet type. In muLinux (version > 2.7,
setup ipfwadm) You can enable IP masquerade feature and IP generic
protection on a Linux server, allowing connected computers (running TCP/IP, but
without registered Internet address) to connect to the Internet through your
The floppy is made up of 1722 blocks of size 1024K. It is logically divided into three parts:
An ext2 non-compressed (i.e. mountable) file-system. It will be mounted
A gzipped ext2 file-system image, obviously mounted under
A bzipped ext2 file-system image. It will be mounted under
The X11 floppy addon (1772K) is, instead, in tarred+bzipped (tbz) format.
The kernel is loaded, as usual, via LILO. When the kernel is loaded, it
/sbin/init. BOOT is mounted from the floppy under
/startup, while USR is mounted under
/startup we are able to permanently save to
floppy our muLinux profile: see section The setup
Startup scripts take also care about creating a fourth partition into RAM,
The Linux kernel has a limited capability to accept information at boot in ther form of var=value entry. In general, this is used to supply the kernel with information about hardware parameters.
Boot-prompt arguments typically only apply to hardware drivers that are compiled directly into kernel, so in muLinux this feature is rarely useful.
If You, at "boot:" prompt, press [SHIFT] or [TAB] key, LILO waits for the name of a boot image (in our case: mulinux) and pass command-line options to the kernel. Example:
boot: mulinux root=/dev/hdb2 vga=extended
This is a brief list usable with muLinux kernel:
specifcs the VGA text mode: normal (80x25), extended (80x50), or "ask".
mount this device as root partition.
specifics the name of init program to execute, ex. /bin/sh, or /bin/rc.1,etc. This is useful for recovery purpose.
specifics the amount of installed memory (if BIOS report is bad).
avoid muLinux root loading.
If You want to supply an alternate mountable root floppy, instead of muLinux standard ramdisk (low-memory system) you can type:
boot: mulinux load_ramdisk=0
The kernel ask you "Insert ROOT floppy ..."
If You want mount an existing EXT2 root partition, type:
boot: mulinux root=/dev/hd...
This list is always a work in progress: whenever I free space on the floppy the list will grow.
Release >4.2 comes with a set of mini-apps, based on "muless", a less-like programmable ncurses interface:
RNA, mail & news reader;
Pion, File Manager with FTP and rustic VFS support;
whois, looks up records in the Network Information Center (NIC) database;
info, System info;
help, small "hypertextual" help system;
mon, resource monitor (/proc based);
muhex, an hexadecimal editor (v>5.3)
/bin/ash: I know it's ugly, but it is much smaller than bash
and it's the same as far as scripts are concerned. "Command history"
approximated support with
help interactive command (VAX style) is
available. Some true man pages are in GCC floppy addon.
elvis tiny (standard UNIX vi clone) and
Editor (but this on X11 floppy).
Many national keyboard mappings. Codepages: 437,850.
Serial mouse. Bus Mouse: PS/2 (aux port style): /dev/psaux; Logitech BUS Mouse: /dev/logibm; Microsoft BUS Mouse: /dev/inportbm. gpm mouse server (v>6.0, EXT).
Dos, UMSDOS, Windows, vfat, NFS (
nfs.o module), WfW/NT fs
share Samba/SMB (
smbfs.o module), cdrom (
module). Commands like
m4 macro processor,
bc calculator (emulated with
Release > 4.2 comes with
awk language and a set of new
classical UNIX command based on them, like:
I dreamt of not including
gzip and using the
option of tar. But tar only gunzips...
You won't find either
unzip: these are
rather big. Maybe in the future.
lp.o module, by request plus a simple
escape codes (no spooler). muLinux support only ASCII, POSTSCRIPT (i.e. Apple
Laserwriter) and HP-PCL (i.e. Laserjet) printer, but print only this format:
ascii, pgm, tiff (g3,fax). Starting from 4.0 release, muLinux support also
remote UNIX printers, BSD style (contributed by Tom Poindexter
(firstname.lastname@example.org). Starting from 6r3 release muLinux support an LPD server,
contributed by Steve Flynn (email@example.com): a little C program which
understand the traditional BSD lpd printer protocol (RFC1179). Enabling this
daemon, your host may act as a simple Print Server or Print Sharer for UNIX
machines, for WinNT ( using "Microsoft TCP/IP Printing" driver) or for Windows
95/98 (using a FREE program, called ACITS LPR )
Timeout is used by the drive to determine how long to wait (with no disk activity) before turning off the spindle motor to save power.
ipfwadmfor masqueranding & forwanding processes,
ftpget(a small FTP client, suitable for scripting),
netcat, a general purpose TCPUDP port scanner.
sniffitpacket sniffer and monitoring tool
nmap(rustic) network mapper
sshSecure Shell (on EXT addon)
ne (NE1000, NE2000, and
ne2k-pci (PCI ne2000 clones),
3c59x ( the 3Com
"Vortex" and "Boomerang" series ethercards,Fast EtherLink
3c590/3c592/3c595/3c597, XL 3c900 and 3c905 cards), ..., but the modules are
on the floppy. You just have to gzip your own module, and put it on the
floppy. See section How can I
personalize muLinux? for further details.
Dynamic Host Configuration Protocol; muLinux (>4.2) support a
dhcpcd configured client. DHCP allows hosts on a TCP/IP network
to request and be assigned IP addresses, and also to discover information
about the net- work to which they are attached.
pppd commands. Configuration is automatic
and you start PPP typing
ppp-off. PPP mulinux setup also provide a way to link together
two PCs (or a local network to the Internet), via null-modem serial cable.
muLinux (hyper-rustic) diald is a daemon based on an IP accounting's hack. Enabling diald, muLinux detected outgoing DNS request to some remote NAMESERVER (port 53) and start PPP (or what you want, of course)
the traditional UNIX command scheduler.
fetchmail only a few K, perfectly working, with the
-F (flush) option, but also a true
sendmail compatible with the real one, wich support
smarthost and offline processing. I tested it with pine from my "big" Linux.
You can use the
From: field you prefer (
Mail processing with
RNA Messenger, symlink `mail` (offline
RNA, newsreader mode +
suck (pull small newsfeed from usenet;
emulated with scripts).
Starting from 7.0, mulinux support inetd, wu-ftpd, in.rlogind. Multi-user is now enabled, with login and password.
Starting from 7.0 release, muLinux support PCMCIA card (EXT addon). Tested on IBM Thinkpad with 3c589 card and ACER Extensa 5027, with ne2000 compatible card.
mitermcommand, similar to
minicom, for remote modem session.
agetty(dialin session) and
efax(send, receive fax)
fax script allows You to make,send,receive and print fax
efax packages (C) Ed. Casas. Tested with USR
Sportster 3.66, but will work with any modem, I hope.
sound.omodule (SoundBlaster) and
PC-Speakermodule+patch (by Michale Beck). On my PC the SoundBlaster works. In some cases it may be necessary to give the kernel extra options
mpg123to play MPEG files (layers 1-2-3) (X11 addon)
vrecto record with your microphone.
playcdto listen to cd.
.aufiles directly to
lynx, version 2.6 a fully-featured World Wide Web (WWW) client for users running cursor-addressable, character-cell display devices (e.g., vt100 terminals, vt100 emulators running on PCs or Macs, or any other character-cell display). It will display Hypertext Markup Language (HTML) documents containing links to files on the local system, as well as files on remote systems running http, gopher, ftp, wais, nntp, finger, or cso/ph/qi servers, and services accessible via logins to telnet, tn3270 or rlogin accounts.
netcat. Its one and only notable feature is its size in bytes: 3713.
inews(emulated) used by Lynx for newsgroup posting.
Chimeragraphical Web Browser (in X11 addon)
Starting from release 2.3, muLinux comes with some rustic "servers and daemons" support. A muLinux server is, generally, a shell script (often netcad based) running via init(8) at "runlevel 5", without inetd. Servers shutdown with "init s" and restarts with "init 5"; "init q" update the init(8) status. This list will grow, I hope.
PygmyWWW server, a simple httpd server (2202 bytes), supporting multi-connections,download and directory browsing. Try with lynx://localhost/. Recents releases run also a CGI capable HTTP server (thttpd) and comes with a nice CGI front-end to internal setup engine (mu-RCP).
atd) daemon for deferred execution (command like
fortune (classical Linux fortunes, in latino),
piano (sound games)
reverse, blue (solitaires).
carbo (crypto games)
mu -i command supports creation of various floppy models, of
size 1440K or 1770K. For example, the two floppy model BOOT+ROOT(1722K) and
USR(1722K), allows to increment the number of binaries put in ROOT
/bin) and in USR (
The model BOOT+ROOT(1440K) and USR(1722K) boots much more rapidly.
-i has a drawback: DOS-installers cannot choose the model but they must
accept the default BOOT+ROOT+USR on a single 1722K floopy. This is because LILO
is not available as a DOS program. Tecnically, building a floppy is just a
command similar to
cat BOOT ROOT > /dev/fd0, but LILO is
necessary to modify the MBR. I do not know a simple way to do this under DOS
(without LILO). Finally I don't think that distributing a BOOT.1440 and a
BOOT.1722 would be a good idea.
See also the file doc/custom.txt in dist archive.
Neccessary kernel functionality to do 'mu -r':
- loopback device support
The right versions of 'fdformat', 'lilo' and 'bzip2' are included.
The root partition resides on the floppy, split into two parts (see section
happens at boot time?): The first part (ROOT) just contains the directory
The first thing to do if you want to build a custom muLinux is to unpack the
BOOT,ROOT,USR and X11 images with the command
mu -u. It will unpack
the BOOT partition under subdirectory
tree/startup and ROOT+USR+X11
Now, add, wipe, replace commands as you like.
If you want to change the kernel, compile it with
and copy it under
tree/startup/boot/mulinuz. The necessary modules
must be gzipped and copied in
tree/startup/modules/README, for details).
It is often necessary to specify parameters like
irq and so on when you load a module. If your
module needs extra parameters just write them into
tree/startup/modules/X.param, remembering that muLinux loads
modules with a command equivalent to this
insmod X.o `cat X.param`
Please note that you have to compile
UMSDOS file-system support and
directly into the kernel because they are needed at boot time for UMSDOS muLinux
If you look into the
mu script you will find a variable called
BOOT_FREE: with it you can tune the free space you want on the BOOT
partition, where all configurations are saved permanently and where you may want
to save you emails for instance.
Custom keymaps are located under
You can save a
mailrc and/or a
You will find the contents of this directory under
You may change this directory without restrictions. If you ran out of space this
is the place to look if you want to purge commands. Remember that
lynx is the biggest executable on the floppy.
When you finished customizing muLinux just type
to rebuild the floppy-image. Pay attention to error messages! If everything works fine reboot now your brand new muLinux!
mu -r mu -x # this if for X11 subsection
This addon consists, basically, of the VGA-16 XServer, the fvwm95-2,
Afterstep and wm2 Window-Manager and the XFM Application & File Manager.
muLinux mounts the content of this floppy (approximately 4.2M not compressed)
/usr/X11R6. You will find the new binaries and libraries into
Configuration files are located under
initial choice of X11R6 developers. Maybe you want to take a look at the
/usr/X11R6/lib/X11/XF86Config: configuration of the X server;
/usr/X11R6/lib/X11/fvwm95-2/*: fvwm configuration files;
/usr/X11R6/lib/X11/afterstep/*: afterstep configuration files;
/usr/X11R6/lib/X11/xfm/*: xfm configuration.
The XKB feature is disabled: national keyboards are directly exported into X. Finally, a lot of fonts were simply deleted.
Anyway, you will find these X programs: xcalc, xclock, xload, xhost, xmodmap,
xsetroot, xinit, xcal, xmixer, pyro, xsnow and xterm (rxvt).
can be used to run every text-mode muLinux command (lynx, minicom, workbone,
xhost is interesting because it allows the local X server
to display applications running on a remote workstation.
If you have 16-32M of avalaible RAM, X will run at a terrific speed!!!!
This 1722k floppy, coming with 6.0 release, is intended as a repository of kernel modules, optional binary, etc. Currently: gpm mouse server; SCSI support, ssh (Secure Shell), lilo and syslinux (boot manager), mkisofs and cdrecord (for CD burning), sox and cdda2wav, the Samba Suite v1.9.18a, etc. EXT is mounted on /usr/local/.
XVnc X-Server (from Virtual Network Computing) and relative clients; SVGA-lib; zgv thumbnail image viewer. X11 required.
An add-on floppy for muLinux to add a healthy mix of application programs written in Tcl/Tk. Requires the muLinux X11 add-on, as most Tcl programs included are X11 based. Author: Tom Poindexter, firstname.lastname@example.org.
LaTex: TeX typesetting system for UNIX-like systems, with AMSTex (from American Mathematical Society) package, dvips, xdvi, etc. The addon contains also Lyx: the popular X frontend to LaTex.
This addon can be used as tool for emergency professional typesetting, if you work as sturm-reporter in some war-zone, around the world, and wish urgently to rewrote the "Book 8th, Conic's Section" of Apollonio di Perga (never found; I'm curiousus).
In this 1722K floppy, coming with 4.0 release, some utitily for C developers.
as-- the portable GNU assembler.
gcc-- GNU project C Compiler (v2.7.0)
cpp-- The GNU C-Compatible Compiler Preprocessor
make-- GNU make utility to maintain groups of programs
ar-- create, modify, and extract from archives.
ld-- the GNU linker
ldd-- print shared library dependencies
ldconfig-- determine run-time link bindings
strip-- discard symbols from object files.
flex-- fast lexical analyzer generator ("lex" replacement)
bison-- GNU Project parser generator (yacc replacement)
f2c-- FORTRAN to C translator.
p2c-- turbo-PASCAL to C translator.
qb2c-- Quick-BASIC to C translator (source package)
g48-- C to RPN (Reverse Polish) translator for HP48G
ddsbasic-- a small BASIC interpreter (6372 bytes!) (source package)
Moreveor: trues UNIX man pages and test-sources in /gcc/usr/src.
This is the muLinux EMU(lators) addon. It contains:
-- DOSEMU v0.66, the Linux DOS Emulator -- WINE v981018, the Linux Windows Emulator -- mtools v3.8, DOS commands in the Linux box
Because most of this programs requires libc6 and libX11 to works, this addon depend from the PERL and X11 addons. Wine, on the other hand, requires XWindow up and running; DOSEMU, doesn't.
The addon is mounted on /usr/emu. Please, look in the directories /usr/doc/help and /usr/emu/doc for more info.
-- DOSEMU starts typing 'dos' (see dos -h) -- WINE starts typing 'wine' (see wine -h) -- swap is strongly suggested running WINE
Alert! DOSEMU and WINE are alpha software; they can crash/destroy your DOS/WIN9x installations: handle with care.
This document was written in SGML, and then rendered using the sgml-tools package.
You can find the latest version of this document at http://sunsite.auc.dk/mulinux/.
End of the MuLinux README. (You can stop reading here.)