tsort <<EOF > 3 8 > 3 10 > 5 11 > 7 8 > 7 11 > 8 9 > 11 2 > 11 9 > 11 10 > EOF 3 5 7 11 8 10 2 9
Wow, you sure wouldn't know how to use it, or what a valid input file looked like, by reading man tsort!:
DESCRIPTION Write totally ordered list consistent with the partial ordering in FILE.