Very Computer

Hi,

Could someone please point me to supplimentary documentation about
the format and data structure that "mt" and "tar" use on tapes.
If it should be hardware specific, I'm using a AKRO with vedio-8 tapes.

I need the information just to understand each "mt" commands exactly.
I tried to rewind the tape one file backwards and read it again with
"bsf", but I cound not read that until I tried the second time to read.

Any of your answers is highly appreciated.

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[...]

Quote:> I need the information just to understand each "mt" commands exactly.
> I tried to rewind the tape one file backwards and read it again with
> "bsf", but I cound not read that until I tried the second time to read.

`mt bsf' positions the head *before* the filemark, i.e. at the end of
the previous file. Use `mt bsfm' instead, or skip over the filemark
with `mt fsf' after rewinding. BTW to re-read the file you just wrote,
you usually have to run `mt bsfm 2'.

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I think this may be a OS specific answer. My implimentation of mt (SunOS
4.1.x does not have a bsfm option. Instead it has nbsf and asf. From the
man pages:

nbsf  Back space count files. The tape is positioned
      on the first block of the file. This is eqivalent
      to count+1 bsf's followed by one fsf.

asf   Absolute space to count file number. This is
      equivalent to a rewind followed by a fsf count.

Check out the man pages on your system to see which works for you.

--
David R. Steiner                                                ISPA                
Research Assoc./Sys Admin                       University of Vechta
Remote Sensing/GIS                                   Vechta, Germany
*All decisions are based on insufficient evidence.-Nickel Hunsenmeir*