Three ways to get the same sorted output, two of them redirection

Answer

sort < students > sorted sort 0< students 1> sorted sort students > sorted

The first two are the same command written two ways — the explicit descriptor numbers change nothing. In the third, students is an argument, so sort opens it itself and descriptor 0 stays on the keyboard.

S&K 3e ch9 §9.3–9.5, §9.10