How to Install muLinux
on a Single Floppy Disk

muLinux is a miniaturized, but nearly full-featured distribution (i.e., version) of Linux that can fit on a single floppy disk.

It allows almost any personal computer to be converted nearly instantaneously into a powerful command line (i.e., all-text mode) Linux machine by simply inserting the floppy disk and rebooting (i.e., restarting) the computer. There is nothing to install on the hard disk drive (HDD). The computer can be turned back into the original operating system (e.g., Microsoft Windows) by merely removing the floppy disk and rebooting again.

Consequently, muLinux can be very useful for educational purposes, for system repair and as a forensic tool. For example, a number of schools use it because it allows students to obtain Linux experience on existing, older Microsoft Windows computers for which it is impractical to install a second operating system.

muLinux is often used by system administrators and others to facilitate repairing computers that will not boot (i.e., start) and to restore lost passwords. This can be done not only for Linux systems but also for computers running Microsoft Windows and other operating systems.

Although there are several other single-floppy Linux distributions, none of them provide muLinux's unique combination of useful features, which include (1) a very large number of standard Linux commands, (2) use of the ext2 Linux native filesystem, (3) the ability to save user configuration data on the floppy for subsequent use, (4) the ability to connect to the Internet and allow access to common network services, (5) the ability to be installed on a HDD if desired, (6) various extensions, including a GUI (graphical user interface), available for installation on additional floppies and (7) no charge or restrictions on use (i.e., free software).

It is a simple matter to install muLinux on a single floppy disk using a Linux computer for which root (i.e., administrative) access is available. The first step is to download the approximately 2.0MB compressed file from the download page of the muLinux web site1. The version listed on the download page as of June 2005 was mulinux-14r0.tgz, which was released in February 2004. The version on the Sourceforge alternative download page was mulinux-13r2.tgz as of the same date. Although it is a good idea to test the authenticity of the download by using the MD5 signature, the signature that is posted on the download page on the muLinux website is for version 13r2 and has not been updated for 14r0.

The next step (actually, this step can precede the downloading, if desired) is to make a directory in which to place this download. The instructions on the muLinux website say to make the new directory in the /root directory, which is the home directory (i.e., the directory which a user is in when it first logs into the system) of the root account (i.e., administrative user). This is accomplished by becoming the root user and issuing the command

mkdir /root/mulinux

As it is good practice to avoid becoming the root user and to work as an ordinary user to the extent possible, this new directory could, alternatively, be created by an ordinary user in its home directory. This would be accomplished with the following command, assuming that the user currently is in its home directory:

mkdir mulinux

Once the new directory has been created, the downloaded file can be moved into it using the mv (i.e., move) command. Assuming that the file was downloaded into the user's home directory, that the new directory was named mulinux, that the new directory was created in the user's home directory and that the user is currently in its home directory, the following could be used to move the directory:

mv mulinux-14r0.tgz mulinux/mulinux-14r0.tgz

The same command could be used assuming that the file was downloaded into the /root directory, that the new directory was named mulinux, that the new directory was created in the /root directory and that the user is currently in the /root directory.

The compressed download is now ready for decompression and extraction of the various files and directories. This can be accomplished by changing the current directory (i.e., the directory in which the user is currently working) from the user's home directory (or from the /root directory) to the new mulinux directory by using the cd (i.e., change directory) command, i.e.,

cd mulinux

Then the compressed download can be decompressed and separated simultaneously by issuing the command

cat mulinux-14r0.tgz | gzip -dc | tar -xf-

The cat command reads the compressed file and pipes (i.e., sends) its output to gzip, which decompresses it. This output, in turn, is piped to tar, which separates it into the original files and directories.

The contents of the mulinux directory can be viewed using the ls command to confirm that the download has actually been decompressed and separated. More detailed information can be obtained by using ls with its -a, -l and -s options, i.e.,

ls -als

Among the various files and directories will be a file named mu, which is the script (i.e., short program) that can be used to install muLinux on a floppy disk.

The next step is to insert a floppy disk into the floppy drive. Ideally, it should be a new 3.5-inch, standard floppy disk and one that is already preformatted for MS-DOS or Microsoft Windows use. A new one is desirable in order to minimize the chances of bad blocks, i.e., sections of the disk that have become damaged. If an old floppy is used, it might be necessary to first reformat it with the fdformat command, i.e.,

fdformat /dev/fd0

One thing that initially confused many new users of muLinux was the instruction, at least on earlier versions of the muLinux website, that said to install the system on a 1.722MB floppy disk. This left many potential users puzzled and wondering where a floppy of this capacity could be obtained. Actually, the solution is very simple, as any standard 1.44MB floppy can be formatted to this capacity by specifying it when using the fdformat command, i.e.,

fdformat /dev/fd0H1722

This 1.722MB formatting is performed automatically, at least on the newest version of muLinux, by the mu installation script, and thus it is no longer mentioned prominently on the web site.

It is necessary to be the root user to execute the mu script. If not already the root user, this can be accomplished on a computer to which the user has root access (i.e., access to the root account) by using the su (i.e., substitute user) command by entering


then pressing the ENTER key, typing in the root password when prompted by the system, and then pressing the ENTER key again.

Now the mu script can be executed. This is done by preceding it with a dot and a slash and using its -i option, i.e.,

./mu -i

After pressing the ENTER key, a list of choices will be presented for the different installation options. The default choice, which is for a single floppy installation, is the first one. It is labeled 1) BOOT+ROOT+USR (1722K), and it can be selected by merely pressing the ENTER key. This produces a confirmation statement Do You want to superformat it (y/n) ? [y]>. The default answer is yes, so all that is necessary is to push the ENTER key again and the installation process begins.

The installation should be completed in a minute or so, and a message will then appear on the monitor screen that says Done. Reboot now. The new single-floppy Linux distribution is ready to use, and it can be tested by leaving it in the disk drive and rebooting the computer.

The first time that the new muLinux floppy is used there will be a long series of configuration questions to answer. The best solution in most cases is to just select the default answer for each by pressing the ENTER key each time. These answers can be saved on the floppy so that it is not necessary to answer them all again on subsequent uses.

After configuration has been completed, the welcome command can be used to provide a tour of the built-in muLinux documentation. Beware the message that says configuration completed; reboot now to complete installation? -- this is intended to be a joke understandable to those who have experienced installing the Microsoft Windows operating systems.

The settings made when first using the disk can be saved as a default profile so that muLinux starts and begins to work immediately in the future. This is done after logging in (any login name can be used) by issuing the command

setup -s

The muLinux floppy is now ready to put into a pocket or purse to keep available to turn any PC into a powerful Linux machine in minutes.

1 muLinux's download page is

Created June 18, 2005.
Copyright © 2005 The Linux Information Project. All Rights Reserved.