varf (available here) is a Perl script that can read an XMD output file (typically a *.xmo file) and gather data read there into columns. This can be useful for analyzing the results of a repetitive calculation, such as when you apply successive increases in strains and print the corrsponding energy.

Here is the description that varf prints when run without arguments.

   varf -s -d<n-deriv> <InputFileName> <VName1> [<VName2> ..]
   Scans input file for lines of the form
      <VName> value
      All values are collected into an array and then printed.
      The first variable is taken to be the independent variable,
      the remaining variables are considered dependent.  The
      independent variable need not be in ascending order, this
      program will automatically sort them.  (This is suppressed
      by the -s option).
      If <n-derivative> is 1 or greater, then the n'th derivative
      is taken for the all variables with respect to the first.
      If only one variable is used, then n'th difference of that
      variable is used instead.
      This program is useful for getting data from text files for
      use with gnuplot.  From gnuplot, you can use this command
      for example.
        plot '< varf -d1 compress.xmo A0 ENERGY' with lines