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8.8.1.3: MTBSF

C code
struct mtop op = { MTBSF, COUNT };
result = ioctl(tapefd, MTIOCTOP, &op);

Description

Backward space over COUNT file marks. The tape is positioned at at the EOT (End Of Tape) side of the last skipped file mark.


Caveats

Note that `mt -f /dev/qft0 bsf' (i.e. COUNT set to 1) always stays within the same tape volume and has the effect to position the tape at the beginning of the current volume which is exactly what should happen if one skips over the previous file mark and positions at the EOT side of it. Think about it!

This might differ from the original behaviour of ftape-2.x or sftape, but is the expected behaviour of a Un*x tape device. See Changed MTBSF and EOM semantics.


Notes

You need to use the non-rewinding devices when using this with the mt program, see Rewinding devices and tape motion commands.


Example

Space to the beginning of the previous file. COUNT has to be set to `2' to accomplish this.

mt -f /dev/nqft0 bsf 2

References
File marks.
MTFSF.
Rewinding devices and tape motion commands.
MTFSFM.
MTBSFM.
MTWEOF.

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