The tools from the graph toolbox can be connected in the same way. Then the first program would contain the -f option, while the last tool in the command line would contain the -o option.
gr_sort -f test.dat | gr_del\_double -eps .001 | gr_analyze
The above programm will count then number of different points and print the result on the screen. When using pipes you must not specify an-f option for any other than the first command. The exception is the use of the -pipe option described above. The pipe would be broken cause the program would not read from pipe, but from file. The same is true for the -o option which is only allowed for the last tool. In this case, the tool after the -o option would wait for additional input from keyboard. The tools can not check the wrong use of these options.
Lots of examples on how to combine the tools will follow in the next section.