FXPOSIT

     Return the unit number of a FITS file positioned at specified extension

     The FITS file will be ready to be read at the beginning of the
     specified extension.

     unit=FXPOSIT(FILE, EXT_NO, /READONLY, COMPRESS=program, /SILENT)

     FILE    = FITS file name, scalar string
     EXT_NO  = Extension to be moved to, scalar nonnegative integer

     Unit number of file or -1 if an error is detected.

     /READONLY - If this keyword is set and non-zero, then OPENR rather
                than OPENU will be used to open the FITS file.
     COMPRESS - If this keyword is set and non-zero, then then treat
                the file as compressed.  If 1 assume a gzipped file.
                and use IDLs internal decompression facility.    For Unix
                compressed or bzip2 compressed files spawn off a process to
                decompress and use its output as the FITS stream.  If the
                keyword is not 1, then use its value as a string giving the
                command needed for decompression.
     /SILENT    If set, then suppress any messages about invalid characters
                in the FITS file.

      None.

      Opens and returns the descriptor of a file.

      Open the appropriate file, or spawn a command and intercept
      the output.
      Call FXMOVE to get to the appropriate extension.

      EXPAND_TILDE() (pre V5.5 Unix only), FXPAR(), FXMOVE(), REPSTR()

      Derived from William Thompson's FXFINDEND routine.
      Modified by T.McGlynn, 5-October-1994.
       Modified by T.McGlynn, 25-Feb-1995 to handle compressed
          files.  Pipes cannot be accessed using FXHREAD so
          MRD_HREAD was written.
       W. Landsman 23-Apr-1997    Force the /bin/sh shell when uncompressing
       W. Landsman 26-May-1997    Non-unix is not just VMS
       T. McGlynn  22-Apr-1999    Add /binary modifier needed for Windows
       T. McGlynn  03-June-1999   Use /noshell option to get rid of processes left by spawn.
                                  Use findfile to retain ability to use wildcards
       W. Landsman 03-Aug-1999    Use EXPAND_TILDE under Unix to find file
       T. McGlynn  04-Apr-2000    Put reading code into FXMOVE,
                                  additional support for compression from D.Palmer.
       W. Landsman/D.Zarro 04-Jul-2000    Added test for !VERSION.OS EQ 'Win32' (WinNT)
       W. Landsman    12-Dec-2000 Added /SILENT keyword
       W. Landsman April 2002     Use FILE_SEARCH for V5.5 or later
       W. Landsman Feb 2004       Assume since V5.3 (OPENR,/COMPRESS available)
       W. Landsman,W. Thompson, 2-Mar-2004, Add support for BZIP2
       W. Landsman                Don't leave open file if an error occurs
       W. Landsman  Sep 2004      Treat FTZ extension as gzip compressed

[Home Page] [Software, Documentation] [IDL Documentation] [Quick Reference] [Feedback]