1.  columns

  Convention for specifying column numbers on command line

  2.  DESCRIPTION

  This manual page describes the syntax for specifying column numbers on
  the command line of some utilities.

  Normally, columns are specified by their number as they appear in
  input files, starting from one. Each column number must be separated
  by a comma, and no white spaces must appear in the list. For example:

       1,2,5,4

  specifies columns 1, 2, 5 and 4. If the utility outputs data from
  these columns as they appear in the list, this example would also cor-
  respond to a rearranging of columns.

  A comma separated field can also define a range instead of specifying
  the number of a column. The syntax is similar to ranges in Matlab. For
  example:

       3:2:12

  is equivalent to 3,5,7,9,11. However, ranges specified this way must
  contain three values (in contradiction with Matlab where only two val-
  ues are also accepted). If the step value is negative, columns will be
  taken in the reverse order. For example:

       12:-2:3

  is equivalent to 12,10,8,6,4. An increasing range with a step value of
  one can also be specified like

       5-7

  which is equivalent to 5,6,7.

  These formats can be mixed. For example:

       5,2,20:-2:16,1-3,5,6:3:12

  which is equivalent to 5,2,20,18,16,1,2,3,5,6,9,12.

  3.  AUTHOR

  Manual page written by Pierre Jaccard, Geophysical Institute,
  University of Bergen, 1999.