The pset() call sets the value for the infile parameter of dmcopy to "in.fits". We then call pquery() to find its value and - since it is not a hidden parameter - we are prompted for a value. In this example we accept the default value, and so the contents of ifile are "in.fits".

The query of the "clobber" parameter does not result in an interactive query since it is a hidden parameter.

We repeat the first example but this time do not use the default value for infile, instead changing it to "test.fits".

The call to pget() is there to highlight that the "dmcopy" parameter file has not been updated by the pquery() call. This is because it was opened read-only by pquery(); to get the parameter value to actually change requires using paramopen(), as the following example shows.

In this example, since we explicitly open the parameter file as read-write, the pquery() call results in the parameter file being changed.

Here we use the three-argument form of paramopen() to set parameter values as if the command had been run from the command-line. Since the parameter values for "infile" and "outfile" are contained in the parameter list (the args array here), the pquery() calls do not need to ask the user what the value is. And, as the parameter file was opened with a mode of "rw", these new parameter settings are written to the parameter file if the parameter mode is not "hidden".

Although this example was run within ChIPS, it is more likely to be useful when run from a S-Lang script executed by slsh; see "ahelp paramio" for an example of this.