Whole lines are sorted into increasing order, using lexicographic ordering of Unicode characters by default. The sort is stable, so that lines that compare equal will appear in the output in the same order as in the original file. The sort order is affected by the following options:

-n

Each line is assumed to have an initial numeric string representing an integer, with optional plus or minus sign, and the lines are sorted by those numeric values into increasing order.

-r

Reverses the sense of comparisons.