CNSTR(6) CNSTR(6)
NAME
cnstr - Plan B volume constraints and attributes
DESCRIPTION
The Plan B bns(4) program permits the application to mount
at a given mount point those volumes whose names and
attributes match the ones given as arguments, as said in
planb(1).
Volume attributes can be used as constraints to determine
which ones of the volumes available for a given mount point
are of interest for the application. A constraint is a set
of values for attributes that refer to properties of the
resource volume. Both volume announces and volume mount
requests carry a constraint used to pair them.
A constraint is a single argument, field, or string. Its
format is a set of attr=value pairs delimited by white
space. No space may be around the equal sign. Also, when
using rc(1), it is important to quote all the
attribute/value pairs together, or they would become differ-
ent constraints, and not a single one.
ATTRIBUTES
By convention, the following attribute names and values are
used through the system, This convention should be followed
or users will not know how to request a given property for a
resource. Of course, this is highly regional and the version
shown here corresponds to customs at URJC.
Attribute Name Values Description
Type type Type for the resource
serviced. Usually corre-
sponds to the data format
for the device involved.
text text without null charac-
ters.
bin program binary
dir file hiearchy
pcm audio PCM data.
mp3 MPEG 2 layer 3 data.
Arch arch Architecture for the
resource. Commonly used
for bin types.
386 Plan B (or Plan 9), 386.
arm Plan B (or Plan 9), ARM.
lin Linux on 386 PC.
win Windows on 386 PC.
sym Symbian, native.
UI gui User interface service.
CNSTR(6) CNSTR(6)
Identifies the type of
device available.
big Large graphics device
small Small graphics device
txt Text only device
location loc Name used to represent
the location of the vol-
ume. Corresponds to a
directory in /where that
keeps context for the
given location.
user user Identifier used for the
user, to identify volumes
of interest for (or owned
by) a particular user.
machine sys Identifier used for the
machine, to identify vol-
umes served by that par-
ticular machine.
domain dom Identifier used for the
adminstrative domain, to
locate volumes within
domains.
Con net Connection. Specifies the
quality of the link used
to reach the volume.
ok Latency seems to be ok.
bad Latency is a bad one.
Other types and values not documented here may exist,
although those commonly used should be described above. The
convention is that attributes not listed here are not stan-
dard at URJC.
SEE ALSO
planb(1), namespace.planb(4), bns(8), mount(2).