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 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, 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, 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 ´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)