NOTE: *IN* the dir with all the astro-related IDL code:

(tsandstr @ hw-console01:idl/IDLAstro-master/pro) > module load idl
(tsandstr @ hw-console01:idl/IDLAstro-master/pro) > idl
IDL Version 8.1 (linux x86_64 m64). (c) 2011, ITT Visual Information Solutions
Installation number: 209258.
Licensed for use by: NASA - Ames Research Center

IDL> @/homehw/tsandstr/collab/astejko/mfdyn/src/extract.pro

--- extract.pro ---

fits_read,'/nobackupp8/tsandstr/astejko/mfdyn/dat/nt-56/BY.fits',table,hdtable
openw,1,'/nobackupp8/tsandstr/astejko/mfdyn/dat/nt-56/BY.flt'
writeu,1,table
close,1
...
fits_read,'/nobackupp8/tsandstr/astejko/mfdyn/dat/tac-14/W.fits',table,hdtable
openw,1,'/nobackupp8/tsandstr/astejko/mfdyn/dat/tac-14/W.flt'
writeu,1,table
close,1

-------------

module load idl/8.1

To give LINUX system commands from within IDL: enter $ as the first
character on the command line

IDL> fits_info,'/nobackupp8/tsandstr/astejko/mfdyn/dat/tac-14/BX.fits'
% Compiled module: FITS_INFO.
% Compiled module: TEXTOPEN.
% Compiled module: SXPAR.
% Compiled module: GETTOK.
% Compiled module: STRN.
% Compiled module: VALID_NUM.
/nobackupp8/tsandstr/astejko/mfdyn/dat/tac-14/BX.fits has 0 extensions
Primary header: 10 records
Image -- Real*4 array ( 128 64 64 93 )

% Compiled module: TEXTCLOSE.

IDL> fits_read,'BX.fits',table,hdtable
% Compiled module: FITS_READ.
% Compiled module: FITS_OPEN.
% Compiled module: SXPAR.
% Compiled module: GETTOK.
% Compiled module: VALID_NUM.
% Compiled module: SXDELPAR.
% Compiled module: TAG_EXIST.
% Compiled module: FITS_CLOSE.

IDL> help,table
TABLE           FLOAT     = Array[128, 64, 64, 93]

IDL> help,hdtable
HDTABLE         STRING    = Array[10]

IDL> hprint,headfits('BX.fits')
% Compiled module: HEADFITS.
% Compiled module: FXPOSIT.
% Compiled module: MRD_HREAD.
% Compiled module: HPRINT.
SIMPLE  =                    T / Written by IDL:  Wed May 27 17:55:17 2015
BITPIX  =                  -32 /
NAXIS   =                    4 /
NAXIS1  =                  128 /
NAXIS2  =                   64 /
NAXIS3  =                   64 /
NAXIS4  =                   93 /
DATE    = '27/05/15'           / Creation date (DD/MM/YY) of FITS header
EXTEND  =                    T / FILE MAY CONTAIN EXTENSIONS
END

IDL> openw,1,'bx.flt'
IDL> writeu,1,table
IDL> close,1