look-displays lines beginning with a given string

look ”displays lines beginning with a given string

 look [-dfa] [-t termchar] string [file] 

look displays any lines in a file that contain a string as a prefix. As look performs a binary search, the lines in the file must be sorted. If a file is not specified, the file /usr/dict/words is used, only alphanumeric characters are compared, and the case of alphabetic characters is ignored.

OPTIONS:

-d	Dictionary character set and order; i.e., only alphanumeric characters are compared.
-f	Ignores the case of alphabetic characters.
-a	Uses the alternate dictionary /usr/dict/web2.
-t	Specifies a string termination character; i.e., only the characters in string up to and including the first occurrence of the termination character 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.

Example A.34.

 1   %  look sunb   sunbeam   sunbeams   Sunbelt   sunbonnet   sunburn   sunburnt  2   %  look karen sorted.datebook  3   %  look Karen sorted.datebook   Karen Evich:284-758-2857:23 Edgecliff Place, Lincoln, NB   92086:7/25/53:85100   Karen Evich:284-758-2867:23 Edgecliff Place, Lincoln, NB   92743:11/3/35:58200   Karen Evich:284-758-2867:23 Edgecliff Place, Lincoln, NB   92743:11/3/35:58200  4   %  look -f karen sorted.datebook   Karen Evich:284-758-2857:23 Edgecliff Place, Lincoln, NB   92086:7/25/53:85100   Karen Evich:284-758-2867:23 Edgecliff Place, Lincoln, NB   92743:11/3/35:58200   Karen Evich:284-758-2867:23 Edgecliff Place, Lincoln, NB   92743:11/3/35:58200  

EXPLANATION

1. look displays all lines in /usr/dict/words that start with the string sunb , assuming /usr/dict/words is in the current directory.

2. look cannot find a line that starts with karen in a file called sorted.datebook. (The file must be sorted or look will not find anything.)

3. look displays all lines with lines starting with the string, Karen , in file, sorted.datebook .

4. The -f option folds upper and lowercase in the search string (i.e., turns off casesensitivity).