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FXPSEEK

FXPSEEK

Name


  FXPSEEK

Author


  Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770
  craigm@lheamail.gsfc.nasa.gov
  UPDATED VERSIONs can be found on my WEB PAGE:
      http://cow.physics.wisc.edu/~craigm/idl/idl.html

Purpose


  Internal routine to perform seek on a Unix Pipe.

Description



  See the following procedures for appropriate documentation.
    FXGOPEN - open resource
    FXGCLOSE - close resource
    FXGREAD - read from resource
    FXGWRITE - write to resource
    FXGSEEK - seek on resource (i.e., perform POINT_LUN)
    FXGFILTERED - determine if resource is a normal file.

Parameters



  unit - the pipe LUN. If positive, then the file pointer is moved
          to POSITION in the pipe output. [ In reality the file
          pointer is moved in the cache file. ] If negative, then
          the file pointer of the file unit -LUN is returned in
          POSITION.
  position - the file pointer, either passed or returned as defined
              by UNIT.

Side Effects



  The file pointer may be updated.
  Actual file accesses are postponed until needed (ie, when FXPREAD
  is called).

Modification History


  Changed copyright notice, 21 Sep 2000, CM
  $Id: fxpseek.pro,v 1.2 2001/03/25 18:10:47 craigm Exp $



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