DEVDB(4-SVR4) RISC/os Reference Manual DEVDB(4-SVR4)
NAME
DEV_DB - device description database
DESCRIPTION
The directory /dev/DEV_DB contains a set of files that make
up the database used by MKDEV(1M) to create system device
entries. Note that MKDEV uses the subdirectory ./DEV_DB, so
that if MKDEV is run in another directory, the database must
be there.
The database is the concatenation of the following files in
the given order:
common.system
common.local
common.hostname
machine.system
machine.local
machine.hostname
where hostname is found by executing the command hostname(1)
(if it exists) and machine is found by executing uname(1)
with the option -t. Data definitions are overwritten, so
data found in common.system can be overridden by data found
in, for example, machine.system.
The intent of this organization is to make network and
host-specific administration simpler. The .system files are
supplied with the system. The .local and .hostname files
can be maintained on a single ``master'' system and then
copied periodically to the other systems, thus centralizing
the administration task.
The database is a simple hierarchy of device ``classes'' and
``operations''. A class is defined by the syntax
class(name,alias...) {operations}
(NOTE: Separators, such as parentheses and commas, may be
surrounded by spaces and tabs, and the braces may be sur-
rounded by spaces, tabs, and newlines.) Class names and
aliases may not contain spaces, tabs, newlines, parentheses,
braces, or the comment character (#). Comments are any
string beginning with a # and ending with a newline. There
is no way to escape the # character.
As stated previously, the same class may be defined multiple
times, and each definition overrides the previous, thus
allowing the machine-specific and local files to override
the system defaults.
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The operations part of the class definition consists of
listings for devices, ``iterative'' devices, links, ``itera-
tive'' links, messages, and other classes. Listings are
separated by newlines or semi-colons, and trailing semi-
colons are ignored.
A device listing is of the form
device(name,type,major,minor,mode,owner,group)
This creates a device entry called name, with type type (`b'
for block special or `c' for character special), the given
major and minor device numbers, the given mode (number), and
the named owner and group.
An iterative device is a group of devices whose names and
minor numbers are related and have values that increase by
1. An example of an iterative device is the set of standard
terminals, /dev/tty[0-5], which have minor device numbers
0-5. The iterative device listing is of the form
idevice(count,name,start,type,major,minor,mode,owner,group)
This creates a set of count device entries. The name of
each entry is the concatenation of name and a counter begin-
ning at start increasing by 1. The minor device number
starts with minor and increases by 1 for each entry.
A link listing is of the form
link(file,linkname)
This creates a link called linkname to file, which must
already exist.
An iterative link is a group of links whose source and tar-
get names both end with numbers, and each number is incre-
mented by 1. The iterative link listing is of the form
ilink(count,file,start1,linkname,start2)
This creates a set of count device entries. The name of
each entry is the concatenation of linkname and a counter
beginning at start2. The file to be linked in each case is
the concatenation of file and a counter beginning at start1.
A message listing causes a message to be printed on the
standard output when MKDEV is executed. It is of the form
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message(text)
The text field may contain any characters except for separa-
tors (parentheses, commas, semi-colons, and braces), and is
processed by echo(1). Leading and trailing spaces and tabs
are removed, and intermediate whitespace may be compressed
into single spaces. It is therefore best to use \t for
tabs.
All other listings found in a class definition are con-
sidered to be the names of classes, which are effectively
included. For example, if class ``foo'' is defined with a
listing ``bar'', ``bar'' is considered to be a class, and
its listings are included in ``foo''.
It is a good idea to execute MKDEV with the -n option to
check the syntax of the database files after any changes.
EXAMPLES
The following defines the class of terminals, which consists
of /dev/tty, /dev/ttyh0 through /dev/ttyh15, /dev/ttyi0
through /dev/ttyi5, /dev/tty0 through /dev/tty5, /dev/ttym0
through /dev/ttym5, and the special links to the console.
class(tty,terminals) {
device(tty, c, 2, 0, 622, root, bin)
idevice(16, ttyh, 0, c, 16, 0, 622, root, bin)
idevice(16, ttyi, 0, c, 16, 16, 622, root, bin)
idevice(6, tty, 0, c, 0, 0, 622, root, bin)
idevice(6, ttym, 0, c, 0, 64, 622, root, bin)
console
}
class(console) {
link(tty0, console)
link(tty0, systty)
link(tty0, syscon)
}
Executing the command ``MKDEV tty'' or ``MKDEV terminals''
will create all of these files and links, while executing
``MKDEV console'' will only create links to /dev/tty0 if it
exists.
FILES
/dev/DEV_DB Device database directory
/dev/DEV_DB/*.system
Mips-defined device database entries
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/dev/DEV_DB/*.local
Locally-defined device database entries
/dev/DEV_DB/*.hostname
Host-specific device database entries
SEE ALSO
MKDEV(1M).
BUGS
The syntax checking, especially with regard to commas, is
not very thorough, and the syntax error messages are vague.
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