Section: Linux System Administrator's Manual (8)
Updated: 1 November 2002
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makedev - create devices  


makedev <directory> [<device_name>]  


makedev is a program that will create the device files in /dev used to interface with drivers in the kernel.

Note that programs giving the error ``ENOENT: No such file or directory'' usually means that the device file is missing, whereas ``ENODEV: No such device'' usually means the kernel does not have the driver configured or loaded.  


The directory where to create the device files.
Only create device nodes that match <device_name> (wich can be either a canonical name or a regexp). eg:

makedev /dev 'dvb.*' will create /dev/dvb/adapter0/*

makedev /dev hda will create /dev/hda



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.  


Certain devices are required for minimal functionality. These are:
mem - access to physical memory; kmem - access to kernel virtual 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
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
Serial ports.
Pseudo Terminals
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
Standard parallel ports. The devices are created lp0, lp1, and lp2.
Bus Mice
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
Joystick. Creates js0 and js1.
Disk Devices
Floppy disk devices. The device fdx is the device which autodetects 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 controller, and devices fd4* through fd7* are floppy disks on the second controller.
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 partitions 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.
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.
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
SCSI tapes. This creates the rewinding tape device stx and the non-rewinding tape device nstx.
QIC-80 tapes. The devices created are rmt8, rmt16, tape-d, and tape-reset.
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
For compatibility reason (aka historical ``compatibility'' with RedHat), we provide a /dev/scdx entry for each /dev/srx device.
This creates the audio devices used by the sound driver. These include mixer, sequencer, dsp, and audio.
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).
To allow an arbitary program to be fed input from file descriptor 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).
Devices for power management.
Other Devices
Note that the present 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.


makedev 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, processing lines in them like so:
[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 created.
a alias value
Any commands that create devices for alias will also include devices that would be crated for value.


The /etc/makedev.d/* files contains instructions that instrument makdev to create the device files in /dev.  


makedev need to be run by root in order to work smoothly since mknod(2)  won't work for non privilegied users (basically those who don't have EUID==0). Indeed, the mknod(2)  syscall need the CAP_MKNOD permissions (see linux/capability.h)
Usually, any problems we'll find will be confined to the configuration files, which were written by examining the devices.txt file.  


Debian first come with a script building the /dev/* devices files (the makedev script).

RedHat enhanced that idea with the MAKEDEV package. This package was made of two parts :

the first one is a set of config files and script that generate config files. These files usually reside in /etc/makedev.d/.
the second was MAKEDEV, a program written in C that read the /etc/makedev.d/* files to create the actual devices files.

Mandrake further enhanced its predecessors in various ways :

the generator scripts build configuration files that are faster to parse and to handle
there's a new makedev perl program that create all devices in a very fast way



The exit code returned by makedev is either 0 (``no error'') or 255. In that case, an error message will be displayed:
``unrecognized macro MACRO at "LINE"''
makedev didn't recognize the macro MACRO on the quoted line LINE (see makedev(5) for further informations about macros)
``unrecognised line "LINE"''
makedev failled in parsing the line quoted in LINE ; the line did not begin by a character in the [bcls] set


intro(4), devfsd(8), makdev(5).  


Pascal Rigaux <>, 2002
Thierry Vignaud <>, 2002

The device database is heavily inspirated by Redhat one.