SCSITAPE(1)						      General Commands Manual						       SCSITAPE(1)

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 'scsi-
       tape'.

       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 doc-
       umentation 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 ommitted, 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, substan-
       tially 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,  cat /proc/scsi/scsi will tell you what SCSI devices you have.  You can then refer to them as /dev/sga, /dev/sgb, etc. by the
       order they are reported.

       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 'scsi-
       tape' 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)

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