32v 1m look
From Computer History Wiki
LOOK(1) UNIX Programmer's Manual LOOK(1)
look - find lines in a sorted list
look [ -df ] string [ file ]
_L_o_o_k consults a sorted _f_i_l_e and prints all lines that begin with _s_t_r_i_n_g. It uses binary search.
The options d and f affect comparisons as in _s_o_r_t(1):
d `Dictionary' order: only letters, digits, tabs and blanks participate in comparisons.
f Fold. Upper case letters compare equal to lower case.
If no _f_i_l_e is specified, /_u_s_r/_d_i_c_t/_w_o_r_d_s is assumed with collating sequence -df.