Provided by: mtx_1.3.12-18_amd64 
NAME
scsitape - control SCSI tape devices
SYNOPSIS
scsitape [-f <scsi-generic-device>] commands
DESCRIPTION
The scsitape command controls SCSI tape drives in a platform-independent manner. As long as 'mtx' works
on the platform, so does 'scsitape'.
Note that 'scsitape' and your OS's native tape driver may stomp on each other. In particular, if you use
'setblk' and your OS's native tape driver has a different notion of the block size, you may get evil
results. It is recommended to use 'scsitape' only for software where you've written your own low-level
READ and WRITE routines that use the SCSI command set to directly talk to tape drives (i.e., you do not
use the OS's native tape driver at all).
OPTIONS
The first argument, given following -f , is the SCSI generic device corresponding to your tape drive.
Consult your operating system's documentation for more information (for example, under Linux these are
generally /dev/sg0 through /dev/sg15, under FreeBSD these are /dev/pass0 through /dev/passX. Under
Solaris this is usually the same as your tape drive (Solaris has a SCSI passthrough ioctl). You can set
the STAPE or TAPE environment variable rather than use -f.
COMMANDS
setblk <n>
Set the tape drive's SCSI block size to <n> bytes. (NOTE: if you are using your OS's native
tape driver, THIS IS EVIL!).
fsf <n> Go forward by <n> tapemarks.
bsf <n> Go to immediately previous the <n>th previous tapemark. (WARNING: This probably doesn't do what
you expect -- e.g. if you are immediately after a tapemark and type 'bfs 1', it moves to
immediately *before* that tape mark, for a sum total of zero effective movement!).
eod Go to end of data.
rewind Rewind the tape drive.
eject Eject the tape currently in the drive.
erase Does a *short* erase (warning: does NOT work on all drives!).
mark <n>
write <n> filemarks ( 'mark 0' flushes the drive's buffers ).
seek <n> Seek to a logical position <n> that was reported by a previous 'tapeinfo' command.
write <blocksize>
write blocks from stdin to the tape. Chunk the data into <blocksize>-sized chunks. *DOES NOT
WRITE OUT A TAPEMARK!* (you will need to use a subsequent mark 1 command to write out a tape
mark).
read [<blocksize>] [ <#blocks/#bytes> ]
read blocks from the tape, write them to stdout. If we are in variable block mode, <blocksize>
should be zero (note: The maximum block size we currently support in variable block mode is
128K, MAX_READ_SIZE will need to be turned into a settable variable to allow bigger reads). If
<blocksize> is omitted, we assume that we're in variable block mode, and that we are going to
read from tape until we hit a tapemark or end of partition or end of tape.
AUTHORS
This program was written by Eric Lee Green <eric@badtux.org>. Major portions of the 'mtxl.c' library
used herein were written by Leonard Zubkoff.
The SCSI read and write routines are based upon those that Richard Fish wrote for Enhanced Software
Technology's BRU 16.1 product, substantially modified to work in our particular environment (in
particular, all the variable block stuff is new since BRU only does fixed block reads and writes, and the
BRU code uses bitmasks rather than bitfields for the various flags and such in return values, as well as
the BRU code having a different SCSI API and having variable names considerably shorter than the rather
sesquipedalian 'mtx' identifiers). As required by 'mtxl.c', these routines are licensed under the GNU
General Public License.
HINTS
Under Linux, lsscsi --generic will tell you what SCSI devices you have and their device names.
Under FreeBSD, camcontrol devlist will tell you what SCSI devices you have, along with which pass device
controls them.
Under Solaris 7 and 8, /usr/sbin/devfsadm -C will clean up your /devices directory. Then find /devices
-name 'st@*' -print will return a list of all tape drives. /dev on Solaris is apparently only of
historical interest.
BUGS AND LIMITATIONS
for scsitape read 0 <n> where you are doing variable-block-size reads and wish for <n> bytes, it instead
reads one and exactly one block from tape and prints that (no matter what its size). Use 'dd' on the
output of scsitape if you want finer control.
scsitape read 0 attempts reads of MAX_READ_SIZE, which is currently 128K. If blocks on tape are larger
than 128K, only the first 128K will be read -- the remainder will be silently dumped in the toilet.
This program does not interact well (or at all :-) with your OS's native tape driver. You will likely
see weird things happen if you attempt to intermingle scsitape commands with native tape driver
operations. Note that BRU 16.1 for Solaris (and possibly others, but Solaris I know about) will have a
'scsi' keyword to bypass the native tape driver and write via direct uscsi commands, so if you use
'scsitape' to bypass the flaws of the native Solaris driver, you can use BRU 16.1 to write your actual
tape archives. (Assuming that BRU 16.1 has been released at the time that you read this).
AVAILABILITY
This version of scsitape is currently being maintained by Robert Nelson
<robertnelson@users.sourceforge.net> as part of the 'mtx' suite of programs. The 'mtx' home page is
http://mtx.sourceforge.net and the actual code is currently available there and via SVN from
http://sourceforge.net/projects/mtx.
SEE ALSO
loaderinfo(1),tapeinfo(1),mtx(1)
SCSITAPE1.0 SCSITAPE(1)