.TH SG_MAP "8" "January 2001" "sg3_utils-0.92" SG3_UTILS
.SH NAME
sg_map \- displays mapping between sg and other SCSI devices
.SH SYNOPSIS
.B sg_map
[\fI-a\fR] [\fI-n\fR] [\fI-scd\fR] [\fI-sd\fR] [\fI-sr\fR] [\fI-st\fR]
[\fI-x\fR]
.SH DESCRIPTION
.\" Add any additional description here
.PP
Sometimes it is difficult to determine which SCSI device a sg device
name (e.g. /dev/sg0) refers to. This command loops through the
sg devices and finds the corresponding SCSI disk, cdrom or tape
device name (if any). Scanners are an example of SCSI devices
that have no alternate SCSI device name apart from their sg device
name.
.TP
-a
assume the sg devices have alphabetical device names and loop
through /dev/sga, /dev/sgb, etc. Default is numeric scan
.TP
-n
assume the sg devices have numeric device names and loop
through /dev/sg0, /dev/sg1, etc. Default is numeric scan
.TP
-sd
display mappings to SCSI disk device names
.TP
-scd
display mappings to SCSI cdrom device names of the form
/dev/scd0, /dev/scd1 etc
.TP
-sr
display mappings to SCSI cdrom device names of the form
/dev/sr0, /dev/sr1 etc
.TP
-st
display mappings to SCSI tape device names
.TP
-x
after each active sg device name is displayed there are
five digits: <host_number> <bus> <scsi_id> <lun> <scsi_type>
.PP
If no options starting with "-s" are given then the mapping to
all SCSI disk, cdrom and tape device names is shown.
.PP
If the device file system (devfs) is present a line noting
this is output. The "native" devfs scsi hierarchy makes the
relationship between a sg device name and any corresponding
disk, cdrom or tape device name easy to establish. This
replaces the need for this command. However many applications
will continue to look for Linux SCSI device names in their
traditional places. [Devfs supplies a compatibility daemon
called devfsd whose default configuration adds back the
Linux device names in their traditional positions.
.PP
Quite often the mapping information can be derived by
observing the output of the command: "cat /proc/scsi/scsi".
However if devices have been added since boot this can
be deceptive.
.SH EXAMPLES
.PP
My system has a SCSI disk, a cd writer and a dvd player:
.br
   $ sg_map
.br
   # Note: the devfs pseudo file system is present
.br
   /dev/sg0  /dev/sda
.br
   /dev/sg1  /dev/sr0
.br
   /dev/sg2  /dev/sr1
.PP
In order to find which sg device name corresponds to the disk:
.br
   $ sg_map -sd
.br
   # Note: the devfs pseudo file system is present
.br
   /dev/sg0  /dev/sda
.br
   /dev/sg1
.br
   /dev/sg2
.PP
The "-x" option gives the following output:
.br
   sg_map -x
.br
   # Note: the devfs pseudo file system is present
.br
   /dev/sg0  1 0 1 0  0  /dev/sda
.br
   /dev/sg1  2 0 4 0  5  /dev/sr0
.br
   /dev/sg2  2 0 6 0  5  /dev/sr1
.PP
When a SCSI scanner is added the output becomes:
.br
   $ sg_map
.br
   # Note: the devfs pseudo file system is present
.br
   /dev/sg0  /dev/sda
.br
   /dev/sg1  /dev/sr0
.br
   /dev/sg2  /dev/sr1
.br
   /dev/sg3
.PP
By process of elimination /dev/sg3 must be the scanner.
.SH AUTHOR
Written by Doug Gilbert
.SH "REPORTING BUGS"
Report bugs to <dgilbert@interlog.com>.
.SH COPYRIGHT
Copyright \(co 2000, 2001 Douglas Gilbert
.br
This software is distributed under the GPL version 2. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
.SH "SEE ALSO"
.B scsi_info(8)
,
.B scsidev(8)
,
.B devfsd(8)