LOOK(1) General Commands Manual LOOK(1)
look - find lines in a sorted list
look [ -df ] string [ file ]
Look consults a sorted file and prints all lines that begin with
string. It uses binary search.
The options d and f affect comparisons as in sort(1):
d `Dictionary' order: only letters, digits, tabs and blanks partici-
pate in comparisons.
f Fold. Upper case letters compare equal to lower case.
If no file is specified, /usr/dict/words is assumed with collating