UNIX for Dummies Questions & Answers

Hi

<pre>

I get this under /dev/rmt/

lrwxrwxrwx 1 root other 42 Aug 10 13:33 0 -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:
lrwxrwxrwx 1 root other 43 Aug 10 13:33 0b -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:b
lrwxrwxrwx 1 root other 44 Aug 10 13:33 0bn -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:bn
lrwxrwxrwx 1 root other 43 Aug 10 13:33 0c -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:c
lrwxrwxrwx 1 root other 44 Aug 10 13:33 0cb -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:cb
lrwxrwxrwx 1 root other 45 Aug 10 13:33 0cbn -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:cbn
lrwxrwxrwx 1 root other 44 Aug 10 13:33 0cn -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:cn
lrwxrwxrwx 1 root other 43 Aug 10 13:33 0h -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:h
lrwxrwxrwx 1 root other 44 Aug 10 13:33 0hb -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:hb
lrwxrwxrwx 1 root other 45 Aug 10 13:33 0hbn -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:hbn
lrwxrwxrwx 1 root other 44 Aug 10 13:33 0hn -> ../../devices/pci@1f,4000/scsi@3,1/st@5,0:hn



What is the difference between the all these devices? they all look like the same. Have I created too many unused symbolic links? I have only got one dat drive.
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Also when I use:

<pre>

mt -f /dev/rmt/0 rewind and
mt -f /dev/rmt/0cn rewind
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what is the difference??
I went through the 'man mt' but didn't help much.
Can somebody make it clear for me please?

Thanks very much.

On Suns a "ls -lL /dev/rmt/*" will give you a better idea of whats happening. You don't have too many special files, it's supposed to work that way. Each file specifies various different behaviors to be applied during open, read, write, and close calls on that device.

Your example is just rewinding the tape. This is one case where it doesn't matter. It doesn't matter what tape density you pick since rewind is rewind. It doesn't matter is there is an automatic rewind when you close the device since you did a rewind anyway. It doesn't matter what woulda happened had you tried to read past EOF since you didn't. So yes, in the example of just rewinding the tape, it doesn't matter. But someday maybe you will do something with your tape drive besides rewinding a tape. Then it will matter.

The various options are documented on Suns on the mtio man page. Read that and see if you still have any questions.

What type of OS do you have? On HPUX, there is a command lssf that gives you info on device files.

$ /sbin/lssf devicefile

Some older OSs may not have this command.


Try it and see. Also, do a man on lssf.