format(1M)                                                       format(1M)


   NAME
         format - format a disk

   SYNOPSIS
         /sbin/format [-fprsw] [-d datafile] /dev/rdsk/c?d?s?

   DESCRIPTION
         The format command formats a disk device while also creating a block
         which describes the physical layout of the disk (the pdsector).
         format exec's a lower-level format program relating to the device
         driver for that particular device, passing on all the arguments
         given.  The lower-level format program lives in
         /usr/lib/disk_formats/bus/controller_type/format. The
         bus/controller_type part of the pathname is generated by issuing a
         BGETTYPE ioctl.

         Each low-level format program can have one or more datafiles
         associated with it (in the same directory), holding details of the
         fields of the pdsector or formatting parameters for a given disk
         type.

         The /dev/rdsk/c?d?s?  file must be the character special file of the
         device to be formatted.

   OPTIONS
         The following options are recommended to apply to the lower-level
         format program:

         -f    read the pdsector, format the device, and write a pdsector to
               the disk

         -p    print out the data file name associated with the disk that is
               going to be opened and then exit.  This is useful for debugging
               purposes when adding a new disk to a given bus/controller_type

         -r    display the current contents of the pdsector

         -s    set the pdsector in the device driver - that is, the pdsector
               is not written

         -w    set the pdsector in the device driver and also write the
               pdsector to the disk

         -d datafile
               override default data file and use the named datafile instead

         The data file contains one specification line for each individual
         parameter to be set. Each line is delimited by a new line character
         (\n). If the first character of a line is a hash character (#), the
         line is treated as a comment. An example of an entry in a datafile
         would be:


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   format(1M)                                                       format(1M)


           bytespersector = 512

         Parsing of the datafile is up to the implementor of the low-level
         format program; however, a parsing routine called getdiskinfo() is
         provided:

           #include "gfdefs.h"

           getdiskinfo(char *datafile, struct diskformatdesc *diskdes)

         The arguments are:

         datafile
               the name of the datafile file

         diskdes
               a pointer to an array of structures containing a list of which
               fields are to be read from the datafile

         The diskformatdesc structure has the following elements:

         char *dffieldname
               the name of the field to be updated - for example,
               bytespersector

         int dfformat
               field type - HEX, DECIMAL, OCTAL or STRING

         union dfident dfident
               holds either an integer value or a pointer to a string for the
               field name

         int dfstatus
               a status value which is set to VALSTAT(1) if the parsing
               routine managed to fill in the value correctly.  If the value
               to be used is expected to be in the data file, dfstatus should
               be initialized to INVALSTAT(0).

         An example declaration of the parsing structures would be:

           struct diskformatdesc ddatades[] = {
                 "bytespersector", DECIMAL, 0, INVALSTAT,
                 ""
           };

         After a format has been issued, it will necessary to run setvtoc in
         order for the disk to be populated with a VTOC (volume table of
         contents) defining partitions of the disk, etc.





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   format(1M)                                                       format(1M)


   SEE ALSO
         prtvtoc(1M), setvtoc(1M), ioctl(2)

   NOTES
         In /usr/lib/diskformats there is source for an example format
         program that can be used when designing a new format program for a
         particular device (if the implementor so wishes). The header file
         gfdefs.h is also located there.













































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