Provided by: sg3-utils_1.42-2ubuntu1.18.04.2_amd64 
NAME
sg_map26 - map SCSI generic (sg) device to corresponding device names
SYNOPSIS
sg_map26 [--dev_dir=DIR] [--given_is=0|1] [--help] [--result=0|1|2|3] [--symlink] [--verbose] [--version]
DEVICE
DESCRIPTION
Maps a special file (block or char) associated with a SCSI device to the corresponding SCSI generic (sg)
device, or vice versa. Can also be given a sysfs file, for example '/sys/block/sda' or
'/sys/block/sda/dev'.
Rather than map to or from a sg device, the sysfs file name matching a given device special file (or vice
versa) can be requested. This is done with '--result=2' and '--result=3'. This feature works on ATA
devices (e.g. 'dev/hdc') as well as SCSI devices.
In this utility, "mapped" refers to finding the relationship between a SCSI generic (sg) node and the
higher level SCSI device name; or vice versa. For example '/dev/sg0' may "map" to '/dev/sda'. Mappings
may not exist, if a relevant module is not loaded, for example. Also there are SCSI devices that can only
be accessed via a sg node (e.g. SAF-TE and some SES devices).
In this utility, "matching" refers to different representations of the same device accessed via the same
driver. For example, '/dev/hdc' and '/sys/block/hdc' usually refer to the same device and thus would be
considered matching. A related example is that '/dev/cdrom' and '/dev/hdc' are also considered matching
if '/dev/cdrom' is a symlink to '/dev/hdc'.
OPTIONS
Arguments to long options are mandatory for short options as well.
-d, --dev_dir=DIR
where DIR is the directory to search for resultant device special files in (or symlinks to same).
Only active when '--result=0' (the default) or '--result=2'. If this option is not given and
DEVICE is a device special file then the directory part of DEVICE is assumed. If this option is
not given and DEVICE is a sysfs name, then if necessary '/dev' is assumed as the directory.
-g, --given_is=0 | 1
specifies the DEVICE is either a device special file (when the argument is 0), or a sysfs 'dev'
file (when the argument is 1). The parent directory of a sysfs 'dev' file is also accepted (e.g.
either '/sys/block/sda/dev' or '/sys/block/sda' are accepted). Usually there is no need to give
this option since this utility first checks for special files (or symlinks to special files) and
if not, assumes it has been given a sysfs 'dev' file (or its parent). Generates an error if given
and disagrees with variety of DEVICE.
-h, --help
output the usage message then exit.
-r, --result=0 | 1 | 2 | 3
specifies what variety of file (or files) that this utility tries to find. The default is a
"mapped" device special file, when the argument is 0. When the argument is 1, this utility tries
to find the "mapped" sysfs node name. When the argument is 2, this utility tries to find the
"matching" device special file. When the argument is 3, this utility tries to find the "matching"
sysfs node name.
-s, --symlink
when a device special file is being sought (i.e. when '--result=0' (the default) or '--result=2')
then also look for symlinks to that device special file in the same directory.
-v, --verbose
increase the level of verbosity, (i.e. debug output).
-V, --version
print the version string and then exit.
NOTES
This utility is designed for the Linux 2.6 (and later) kernel series. It uses special file major and
minor numbers (and whether the special is block or character) together with sysfs to do its mapping or
matching. In the absence of any other information, device special files are assumed to be in the '/dev'
directory while sysfs is assumed to be mounted at '/sys'. Device names in sysfs are predictable, given
the corresponding major and minor number of the device. However, due to udev rules, the name of device
special files can be anything the user desires (e.g. '/dev/sda' could be named '/dev/my_boot_disk'). When
trying to find a resultant device special file, this utility uses the major and minor numbers (and
whether a block or char device is sought) to search the device directory.
This utility only shows one relationship at a time. To get an overview of all SCSI devices, with special
file names and optionally the "mapped" sg device name, see the lsscsi utility.
EXAMPLES
Assume sg2 maps to sdb while dvd, cdrom and hdc are all matching.
# sg_map26 /dev/sg2
/dev/sdb
# sg_map26 /dev/sdb
/dev/sg2
# sg_map26 --result=0 /dev/sdb
/dev/sg2
# sg_map26 --result=3 /dev/sdb
/sys/block/sda
# sg_map26 --result=1 /dev/sdb
/sys/class/scsi_generic/sg0
Now look at '/dev/hdc' and friends
# sg_map26 /dev/hdc
<error: a hd device does not map to a sg device>
# sg_map26 --result=3 /dev/hdc
/sys/block/hdc
# sg_map26 --result=2 /dev/hdc
/dev/hdc
# sg_map26 --result=2 --symlink /dev/hdc
/dev/cdrom
/dev/dvd
/dev/hdc
# sg_map26 --result=2 --symlink /sys/block/hdc
/dev/cdrom
/dev/dvd
/dev/hdc
EXIT STATUS
The exit status of sg_map26 is 0 when it is successful. Otherwise see the sg3_utils(8) man page.
AUTHORS
Written by Douglas Gilbert.
REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.
COPYRIGHT
Copyright © 2005-2012 Douglas Gilbert
This software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.
SEE ALSO
udev(7), lsscsi(lsscsi)