look - find lines in a sorted list
look [ -dfnixtc ] [ string ] [ file ]
Look consults a sorted file and prints all lines that begin with string. It uses binary search.
If no file is specified, /lib/words is assumed, with collating sequence df.
The following options are recognized. Options dfnt affect comparisons as in sort(1).
|-i||Interactive. There is no string argument; instead look takes lines from the standard input as strings to be looked up.|
|-x||Exact. Print only lines of the file whose key matches string exactly.|
|-d||‘Directory’ order: only letters, digits, tabs and blanks participate in comparisons.|
|-f||Fold. Upper case letters compare equal to lower case.|
|-n||Numeric comparison with initial string of digits, optional minus sign, and optional decimal point.|
|Character c terminates the sort key in the file. By default, tab terminates the key. If c is missing the entire line comprises the key.|
The exit status is ‘‘not found’’ if no match is found, and ‘‘no dictionary’’ if file or the default dictionary cannot be opened.