Plan 9 /sys/man/6/cnstr

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 different 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 corresponds to the data format for the device involved.
text            text without null characters.
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. 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 volume. 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 volumes served by that particular 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 standard at URJC.