MAKEDEV(8) Linux Programmer's Manual MAKEDEV(8)NAMEMAKEDEV - create devices
SYNOPSIS
/sbin/MAKEDEV -V
/sbin/MAKEDEV [ -d directory ] [ -D directory ] [ -c configdir ] [ -m
maxdevices ] [-a] [-n] [-v] [-i] [-M] [-S] [-u] [-x] device ...
DESCRIPTIONMAKEDEV is a program that will create the devices in /dev used to
interface with drivers in the kernel.
Note that programs giving the error ``ENOENT: No such file or direc‐
tory'' normally means that the device file is missing, whereas
``ENODEV: No such device'' normally means the kernel does not have the
driver configured or loaded.
OPTIONS-V Print out version and exit.
-a Always create devices, even if they already exist and have the
proper permissions and file context. The default behavior is to
only (re-)create device nodes which appear to be missing or
whose permissions differ from the configured values.
-m maxdevices
Create no more than the specified number of devices for any
specification in a configuration file.
-n Do not actually update the devices, just print the actions that
would be performed.
-M Create symlinks, directories, and sockets belonging to the cur‐
rent user, and print out the list of devices which would be cre‐
ated in a format which is understood by RPM.
-S Do not actually update the devices, just print the actions that
would be performed in a format which can be fed to a shell.
-d directory
Create the devices under directory instead of the default (usu‐
ally /dev).
-D directory
Compute file contexts for device creation as if the directory
specified for the -d flag were the specified directory. This is
useful if the -d flag is being used to populate a chrooted
device directory.
-u Print the ownership and permissions for devices instead of cre‐
ating them. The information is formatted for use by udev.
-x Create exactly the named device. By default, device names which
have the specified device name as the initial portion of their
name are also created. For example, specifying "tty" will also
trigger the creation of "tty1", "tty2", and so on.
-v Be verbose. Print out the actions as they are performed. This
is the same output as produced by the -n option.
-i Ignore errors parsing configuration files.
CUSTOMIZATION
Since there is currently no standardization in what names are used for
system users and groups, it is possible that you may need to modify
MAKEDEV's configuration files to reflect your site's settings.
DEVICES
Certain devices are required for minimal functionality. These are:
mem - access to physical memory; null - null device (infinite
sink); port - access to I/O ports; zero - null byte source
(infinite source); core - symlink to /proc/kcore (for kernel
debugging); full - always returns ENOSPACE on write; ram -
ramdisk; tty - to access the controlling tty of a process.
Virtual Terminals
console
This creates the devices associated with the console. These are
the virtual terminals ttyx, where x can be from 0 though 63.
The device tty0 is the currently active VT, and is also known as
console. For each VT, there are two devices: vcsx and vcsax,
which can be used to generate screen-dumps of the VT (vcsx is
just the text, and vcsax includes the attributes).
Serial Devices
ttyS{0..63}
Serial ports.
Pseudo Terminals
pty[p-s]
Each possible argument will create a bank of 16 master and slave
pairs. The current kernel (1.2) is limited to 64 such pairs.
The master pseudo-terminals are pty[p-s][0-9a-f], and the slaves
are tty[p-s][0-9a-f].
Parallel Ports
lp Standard parallel ports. The devices are created lp0, lp1, and
lp2.
Bus Mice
busmice
The various bus mice devices. This creates the following
devices: logimouse (Logitech bus mouse), psmouse (PS/2-style
mouse), msmouse (Microsoft Inport bus mouse) and atimouse (ATI
XL bus mouse) and jmouse (J-mouse).
Joystick Devices
js Joystick. Creates js0 and js1.
Disk Devices
fd[0-7]
Floppy disk devices. The device fdx is the device which autode‐
tects the format, and the additional devices are fixed format
(whose size is indicated in the name). The other devices are
named as fdxLn. The single letter L identifies the type of
floppy disk (d = 5.25" DD, h = 5.25" HD, D = 3.5" DD, H = 3.5"
HD, E = 3.5" ED). The number n represents the capacity of that
format in K. Thus the standard formats are fdxd360, fdxh1200,
fdxD720, fdxH1440, and fdxE2880.
For more information see Alain Knaff's fdutils package.
Devices fd0* through fd3* are floppy disks on the first con‐
troller, and devices fd4* through fd7* are floppy disks on the
second controller.
hd[a-d]
AT hard disks. The device hdx provides access to the whole
disk, with the partitions being hdx[0-20]. The four primary
partitions are hdx1 through hdx4, with the logical partitions
being numbered from hdx5 though hdx20. (A primary partition can
be made into an extended partition, which can hold 4 logical
partitions). By default, only the devices for 4 logical parti‐
tions are made. The others can be made by uncommenting them.
Drives hda and hdb are the two on the first controller. If
using the new IDE driver (rather than the old HD driver), then
hdc and hdd are the two drives on the secondary controller.
These devices can also be used to acess IDE CDROMs if using the
new IDE driver.
xd[a-d]
XT hard disks. Partitions are the same as IDE disks.
sd[a-z], sd[a-c][a-z], sdd[a-x]
SCSI hard disks. The partitions are similar to the IDE disks,
but there is a limit of 11 logical partitions (sdx5 through
sdx15). This is to allow there to be 128 SCSI disks.
loop Loopback disk devices. These allow you to use a regular file as
a block device. This means that images of filesystems can be
mounted, and used as normal. This creates 16 devices loop0
through loop15.
Tape Devices
st[0-7]
SCSI tapes. This creates the rewinding tape device stx and the
non-rewinding tape device nstx.
qic QIC-80 tapes. The devices created are rmt8, rmt16, tape-d, and
tape-reset.
ftape Floppy driver tapes (QIC-117). There are 4 methods of access
depending on the floppy tape drive. For each of access methods
0, 1, 2 and 3, the devices rftx (rewinding) and nrftx (non-
rewinding) are created. For compatability, devices ftape and
nftape are symlinks to rft0 and nrft0 respectively.
CDROM Devices
scd[0-7]
SCSI CD players.
sonycd Sony CDU-31A CD player.
mcd Mitsumi CD player.
cdu535 Sony CDU-535 CD player.
lmscd LMS/Philips CD player.
sbpcd{,1,2,3}
Sound Blaster CD player. The kernel is capable of supporting 16
CDROMs, each of which is accessed as sbpcd[0-9a-f]. These are
assigned in groups of 4 to each controller. sbpcd is a symlink
to sbpcd0.
Scanner
logiscan
Logitech ScanMan32 & ScanMan 256.
m105scan
Mustek M105 Handscanner.
ac4096 A4Tek Color Handscanner.
Audio
sound This creates the audio devices used by the sound driver. These
include mixer, sequencer, dsp, and audio.
Miscellaneous
sg Generic SCSI devices. The devices created are sga through sgh
and sg0 through sg7. These allow arbitary commands to be sent
to any SCSI device. This allows for querying information about
the device, or controlling SCSI devices that are not one of
disk, tape or CDROM (e.g. scanner, CD-R, CD-RW).
fd To allow an arbitary program to be fed input from file descrip‐
tor x, use /dev/fd/x as the file name. This also creates
/dev/stdin, /dev/stdout, and /dev/stderr. (Note, these are just
symlinks into /proc/self/fd).
ibcs2 Devices (and symlinks) needed by the IBCS2 emulation.
apm Devices for power management.
Network Devices
Linux used to have devices in /dev for controlling network
devices, but that is no longer the case. To see what network
devices are known by the kernel, look in /proc/net/dev.
Other Devices
Note that the list of devices above is not exhaustive. MAKEDEV
can create more devices nodes. Its aim is to be able to create
everything listed in the devices.txt file distributed with Linux
2.4.
CONFIGURATIONMAKEDEV doesn't actually know anything about devices. It reads all of
the information from files stored in /etc/makedev.d. MAKEDEV will read
any and all files in the subdirectory, skipping over subdirectories,
symbolic links, and device nodes, processing lines in the files like
so:
devices
[b|c] mode owner group major minor inc count fmt [base]
count devices will be created, with permissions set to mode and
owned by owner and group. The first device will be named fmt,
and additional devices will be created if count is larger than
1. If fmt contains a C-style formatting string, it will be
filled with the sum of base and zero. Subsequent devices will
be filled with the sum of base and n * inc, where n is the order
this device is being created in. If the format string did not
already include a format specifier, a "%d" will automatically be
appended to it to make this work.
symbolic links
l linkname target
A symbolic link pointing to target named linkname will be cre‐
ated.
aliases
a alias value
Any commands that create devices for alias will also include
devices that would be crated for value.
macros
=macro expansion
Indicates a macro which can be referenced as $macro in subse‐
quent configuration statements.
CONFIGURATION CONFLICTS
In the event that the set of configuration files contains multiple
rules for a given device name, MAKEDEV will use all of them. The end
result is typically that the last rule given (either by virtue of being
listed below all other matching rules in the same file, or by being
listed in a file which is read after all others which contain alternate
rules) will apply. MAKEDEV reads the set of configuration files in
sorted order, so this misfeature can be exploited dependably.
SEE ALSO
Linux Allocated Devices, maintained by Torben Mathiasen
<device@lanana.org>.
BUGS
Let's hope not. If we're lucky, any problems we'll find will be con‐
fined to the configuration files, which were written by examining the
devices.txt file. If your system uses udev, conflicts between
devices.txt and the in-kernel data which udev uses for naming devices
may crop up. If you find any bugs, please file them in the bug data‐
base at http://bugzilla.redhat.com/ against the "MAKEDEV" component.
AUTHOR
Nalin Dahyabhai, based largely on work done by Nick Holloway and
Michael K. Johnson.
Linux 26 June 2001 MAKEDEV(8)
