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).