| SKIP_LUN on internet sockets? [message #50420] |
Mon, 02 October 2006 12:26 |
news.verizon.net
Messages: 47
Registered: August 2003
|
Member |
|
|
The documentation for SKIP_LUN points out that "since SKIP_LUN actually
performs an input operation to advance the file pointer, it is not as
efficient as POINT_LUN for skipping over a fixed number of bytes in a
disk file". It then goes on to say that SKIP_LUN is useful for the
case of
"Skipping data from a file that is not a regular disk file (for
example, data from an internet socket)."
Makes sense, except I have not actually been able to use SKIP_LUN on an
internet socket.
IDL> print,!VERSION
{ x86 linux unix linux 6.3 Mar 23 2006 32 64}
IDL> help,fstat(unit),/str ;Unit already opened with SOCKET...
** Structure FSTAT, 17 tags, length=64, data length=64:
UNIT LONG 100
NAME STRING 'archive.eso.org.80'
IDL> b = bytarr(1)
IDL> readu,unit,b ;No problem reading 1 byte
IDL> skip_lun,unit,1 ;but using SKIP_LUN to skip a byte gives an
error
% SKIP_LUN: Operation is invalid on a socket. Unit: 100, File:
archive.eso.org.80
I am not sure if this is an error in the SKIP_LUN documentation or if
perhaps SKIP_LUN can only be used with a special class of internet
sockets.... Thanks, --Wayne
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
