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Reading a tape with Unix IDL [message #164] Fri, 11 October 1991 13:58
landsman is currently offline  landsman
Messages: 93
Registered: August 1991
Member
Has anyone succesfully used IDL to directly access a tape on a UNIX
machine? I am coming from a VMS environment and have several procedures
which use the IDL TAPRD function. This function is unavailable in
UNIX IDL. In some cases, I have been able to get around this problem
by first copying the file from tape to disk, e.g.

dd if=/dev/tape of=file.fits bs=2880

and then accessing the disk file with IDL.

However, I have other IDL procedures, (such as those that list FITS
headers on tape), where one does not want to dump the entire tape to disk.
I can imagine a couple of ways in which one might emulate the VMS TAPRD
function.

(1) Write a C function that emulates TAPRD and is linked to IDL via
CALL_EXTERNAL or the SPAWN command.

(2) I am always told that under Unix, that a tapedrive "is just another
device". Perhaps this means that one can access the tape directly using
the IDL READU command.

Anyway, has anyone successfully implemented one of the methods, or found
some other way to access a tape with Unix IDL?

Thanks,

Wayne Landsman landsman@stars.gsfc.nasa.gov
ST Systems Co.
(301)-286-3625
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