For example,
skymap [-par parameter_file] parameter1_name=value1 (...)sets the value of parameter_name in parameter_file, if it is present or else in skymap.par. If the parameter is not found, a new line is inserted into the parameter string just before the END line. Current values of parameters can be modified by replacing the = with a +, to add, or -, to subtract, value. If such an operation is done, the parameter is assumed to be floating point if there is a . within value; otherwise it is assumed to be an integer. If value ends in a "t", it is assumed to be a time of the form hh.mmssss. The parameter value in the parameter file is assumed to be in the same format as value, and the modified parameter is returned to the parameter file in the same format. An argument of -v verifies each operation with a one line message.