setting parameters by command line options

[tueda]

I like to have a command like

grace run w=500 out=w500.dat fmt='w sigma dsigma'

to write the result at sqrt(s) = 500 GeV in the form of <sqrt(s)> <total cross section> <error> to the file w500.dat (w is sqrt(s) in Grace).

A use case is a parameter scan like, on Linux,

for w in $(seq 500 600); do
  grace run w=$w out=w$w.dat fmt='w sigma dsigma'
done

One may use GNU parallel or some batch job systems. Then, the results can be collected by

cat w*.dat | sort -n -k 1

The above is about w, but it might be extended to other model parameters.