Ah, this is an example of one of the many hearts of the CDP system. In a GUI-based effect or instrument, this would involve controlling a rotary knob or a slider. Here in the command line we use a "breakpoint file". The simplest of these is by far the most common. It is a text file containing one or more lines, each with two numeric entries (separated by a space). The first is the time in seconds, and the second value is the required parameter value. The only rules are that (naturally) the first time value must be zero, and subsequent times must always increase. The file is then saved to a name of your choice. By CDP convention, the file extension is "brk", but "txt" is fine too. On the command line, where you would otherwise type an umber for a given parameter, you use the file name instead. The programs handle this internally, kn owing to lookm for either a single number or a file name.
So, a simple example might be:
0.0 1
0.5 2
2.3 4.5
2.4 3.9
3.0 1.1
From which you can gather that the programs will interpolate linearly from the stated values to generate all required intermediate values. Thus, if you just need a plain linear ramp 1->10 from start to end, for a 5-second sound, all you would need is:
0.0 1
5.0 10
