语 法：look [-adf][-t<字尾字符串>][字首字符串][字典文件]
参 数： -a 使用另一个字典文件web2，该文件也位于/usr/dict目录下。 -d 只对比英文字母和数字，其余一慨忽略不予比对。 -f 忽略字符大小写差别。 -t<字尾字符串> 设置字尾字符串。
NAME look - display lines beginning with a given string
SYNOPSIS look [-dfa] [-t termchar] string [file]
DESCRIPTION The look utility displays any lines in file which contain string as a prefix. As look performs a binary search, the lines in file must be sorted (where sort(1) got the same options -d and/or -f that look is in? voked with).
If file is not specified, the file /usr/share/dict/words is used, only alphanumeric characters are compared and the case of alphabetic charac? ters is ignored.
-d Dictionary character set and order, i.e. only alphanumeric char? acters are compared.
-f Ignore the case of alphabetic characters.
-a Use the alternate dictionary /usr/share/dict/web2
-t Specify a string termination character, i.e. only the characters in string up to and including the first occurrence of termchar are compared.
The look utility exits 0 if one or more lines were found and displayed, 1 if no lines were found, and >1 if an error occurred.
FILES /usr/share/dict/words the dictionary /usr/share/dict/web2 the alternate dictionary
SEE ALSO grep(1), sort(1)
COMPATIBILITY The original manual page stated that tabs and blank characters partici? pated in comparisons when the -d option was specified. This was incor? rect and the current man page matches the historic implementation.
HISTORY Look appeared in Version 7 AT&T Unix.