Examples

• If an application asks for a group of input data files, the following are all possible responses:

  
  

     b1,b2,b3,b4
  

  This means ``Use the NDFs stored in files b1.sdf, b2.sdf, b3.sdf and b4.sdf''. If `on-the-fly format conversion' (see SUN/55) is being used, then this example would pick up data files with the highest priority data format (i.e. the format nearest to the start of the list of formats supplied in environment variable NDF_FORMATS_IN). So for instance, if the current directory contained both b1.sdf and b1.fit, then only one file would be used, depending on the relative positions of the .sdf and .fit formats within NDF_FORMATS_IN. If you want to restrict things explicitly to a particular data format, then you should include the corresponding file type in the group expression. An example such as:

     b1.fit,b2.fit,b3.fit,b4.fit
  

  would read just the specified FITS files.

  
  

     cena_b1-
  

  This means ``Use cena_b1.sdf and then (because of the hyphen at the end) ask the user for more data files''.

  
  

     *
  

  This means ``Use all accessible data files in the current directory''.

  
  

     hh1_b1s*_ds
  

  This means ``Use hh1_b1s1_ds.sdf, hh1_b1s2_ds.sdf, etc.''.

  
  

     hh1_b[12]s*_ds
  

  This means ``Use hh1_b1s1_ds.sdf, hh1_b1s2_ds.sdf, etc., and also hh1_b2s1_ds.sdf, hh1_b2s2_ds.sdf, etc.''. The string "[12]" matches either a single character "1" or a single character "2". The string "[0-9]" would match any single digit character. The string "[a-z]" would match any single lowercase alphabetical character.

  
  

     data.fit[12]
  

  This means ``Use files data.fit1 and data.fit2 if they exist. If neither of these files exists, use the twelth image extension in the multi-extension FITS file data.fit''.

  
  

     ^files.lis
  

  This means ``Read the names of data files from the text file files.lis.''

  
  

     ../data/*
  

  This means ``Use all accessible data files contained in the directory ../data''.

  
  

     data_{new,old,back}
  

  This means ``Use files data_new.sdf, data_old.sdf and data_back.sdf''.

  
  

     {^files}_A
  

  This means ``Read names of data files from text file files and append _A to the end of each one''.

  
  

     `grep -l "OBJECT  = 'm57'" *.fit`
  

  The string is enclosed in back quotes (`) which causes the string to be executed as a shell command, and the resulting output to be used as the group expression. Thus this example means ``Use all FITS files that contain an OBJECT keyword equal to 'm57'''.

• If an application asks for a group of output data files, the following are possible responses:

     file1,file2,file3
  

  This means ``Create file1.sdf, file2.sdf and file3.sdf''.

  
  

     ^out.dat
  

  This means ``Read the names of the output data files from text file out.dat''.

  
  

     *_ds
  

  This means ``Append the string "_ds" to the end of all the input data file names.''

  
  

     ../bk/*|_ds|_bk|
  

  This means ``Substitute the string "_bk" for all occurrences of the string "_ds" in the input data file names, and put the files in directory ../bk''.