System Administration Commands devlinks(1M)
NAME
devlinks - adds /dev entries for miscellaneous devices and
pseudo-devices
SYNOPSIS
/usr/sbin/devlinks [-d] [-r rootdir] [-t table-file]
DESCRIPTION
devfsadm(1M) is now the preferred command for /dev and /dev-
ices and should be used instead of devlinks.
devlinks creates symbolic links from the /dev directory tree
to the actual block- and character-special device nodes
under the /devices directory tree. The links are created
according to specifications found in the table-file (by
default /etc/devlink.tab).
devlinks is called each time the system is reconfiguration-
booted, and can only be run after drvconfig(1M) is run.
The table-file (normally /etc/devlink.tab) is an ASCI file,
with one line per record. Comment lines, which must contain
a hash character (`#') as their first character, are
allowed. Each entry must contain at least two fields, but
may contain three fields. Fields are separated by single TAB
characters.
The fields are:
devfs-spec Specification of devinfo nodes that will
have links created for them. This specifi-
cation consists of one or more keyword-
value pairs, where the keyword is
separated from the value by an equal-sign
(`='), and keyword-value pairs are
separated from one another by semicolons.
The possible keywords are:
type The devinfo device type. Pos-
sible values are specified in
ddicreateminornode(9F)
name The name of the node. This is
the portion of the /devices
tree entry name that occurs
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System Administration Commands devlinks(1M)
before the first `@' or `:'
character.
addr[n] The address portion of a node
name. This is the portion of a
node name that occurs between
the `@' and the `:' charac-
ters. It is possible that a
node may have a name without
an address part, which is the
case for many of the pseudo-
device nodes. If a number is
given after the addr it speci-
fies a match of a particular
comma-separated subfield of
the address field: addr1
matches the first subfield,
addr2 matches the second, and
so on. addr0 is the same as
addr and matches the whole
field.
minor[n] The minor portion of a node
name - the portion of the name
after the `:'. As with addr
above, a number after the
minor keyword specifies a sub-
field to match.
Of these four specifications, only the
type specification must always be present.
name Specification of the /dev links that
correspond to the devinfo nodes. This
field allows devlinks to determine match-
ing /dev names for the /devices nodes it
has found. The specification of this field
uses escape-sequences to allow portions of
the /devices name to be included in the
/dev name, or to allow a counter to be
used in creating node names. If a counter
is used to create a name, the portion of
the name before the counter must be speci-
fied absolutely, and all names in the
/dev/-subdirectory that match (up to and
including the counter) are considered to
be subdevices of the same device. This
means that they should all point to the
same directory, name and address under the
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System Administration Commands devlinks(1M)
/devices/-tree
The possible escape-sequences are:
\D Substitute the device-name (name)
portion of the corresponding
devinfo node-name.
\An Substitute the nth component of
the address component of the
corresponding devinfo node name.
Sub-components are separated by
commas, and sub-component 0 is the
whole address component.
\Mn Substitute the nth sub-component
of the minor component of the
corresponding devinfo node name.
Sub-components are separated by
commas, and sub-component 0 is the
whole minor component.
\Nn Substitute the value of a
'counter' starting at n. There can
be only one counter for each dev-
spec, and counter-values will be
selected so they are as low as
possible while not colliding with
already-existing link names.
In a dev-spec the counter sequence
should not be followed by a digit,
either explicitly or as a result
of another escape-sequence expan-
sion. If this occurs, it would not
be possible to correctly match
already-existing links to their
counter entries, since it would
not be possible to unambiguously
parse the already-existing /dev-
name.
extra-dev-link Optional specification of an extra /dev
link that points to the initial /dev link
(specified in field 2). This field may
contain a counter escape-sequence (as
described for the dev-spec field) but may
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System Administration Commands devlinks(1M)
not contain any of the other escape-
sequences. It provides a way to specify an
alias of a particular /dev name.
OPTIONS
The following options are supported:
-d Debugging mode - print out all devinfo
nodes found, and indicate what links would
be created, but do not do anything.
-r rootdir Use rootdir as the root of the /dev and
/devices directories under which the device
nodes and links are created. Changing the
root directory does not change the location
of the /etc/devlink.tab default table, nor
is the root directory applied to the
filename supplied to the -t option.
-t table-file Set the table file used by devlinks to
specify the links that must be created. If
this option is not given, /etc/devlink.tab
is used. This option gives a way to
instruct devlinks just to perform a partic-
ular piece of work, since just the links-
types that devlinks is supposed to create
can be specified in a command-file and fed
to devlinks.
ERORS
If devlinks finds an error in a line of the table-file it
prints a warning message on its standard output and goes on
to the next line in the table-file without performing any of
the actions specified by the erroneous rule.
If it cannot create a link for some filesystem-related rea-
son it prints an error-message and continues with the
current rule.
If it cannot read necessary data it prints an error message
and continues with the next table-file line.
EXAMPLES
Example 1 Using the /etc/devlink.tab Fields
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System Administration Commands devlinks(1M)
The following are examples of the /etc/devlink.tab fields:
type=pseudo;name=win win\M0
type=ddidisplay framebuffer/\M0 fb\N0
The first example states that all devices of type pseudo
with a name component of win will be linked to /dev/winx,
where x is the minor-component of the devinfo-name (this is
always a single-digit number for the win driver).
The second example states that all devinfo nodes of type
ddidisplay will be linked to entries under the
/dev/framebuffer directory, with names identical to the
entire minor component of the /devices name. In addition an
extra link will be created pointing from /dev/fbn to the
entry under /dev/framebuffer. This entry will use a counter
to end the name.
FILES
/dev entries for the miscellaneous devices
for general use
/devices device nodes
/etc/devlink.tab the default rule-file
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWcsu
SEE ALSO
devfsadm(1M), attributes(5), devfs(7FS),
ddicreateminornode(9F)
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System Administration Commands devlinks(1M)
BUGS
It is very easy to construct mutually-contradictory link
specifications, or specifications that can never be matched.
The program does not check for these conditions.
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