look1
Display lines beginning with a given string
Usage
look [options]
string
[file]
Overview
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) was given the same options -d and/or -f that look is invoked with).
If file is not specified, the file /usr/share/dict/words is used, only alphanumeric characters are compared and the case of alphabetic characters is ignored.
Options
-
-a, --alternative -
Use the alternative dictionary file.
-
-d, --alphanum -
Use normal dictionary character set and order, i.e., only blanks and alphanumeric characters are compared. This is on by default if no file is specified.
Note that blanks have been added to dictionary character set for compatibility with sort -d command since version 2.28.
-
-f, --ignore-case -
Ignore the case of alphabetic characters. This is on by default if no file is specified.
-
-t, --terminate character -
Specify a string termination character, i.e., only the characters in string up to and including the first occurrence of character are compared.
-
-h, --help -
Display help text and exit.
-
-V, --version -
Display version and exit.
Exit status
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.
Environment
WORDLIST
Path to a dictionary file. The environment variable has greater priority than the dictionary path defined in the FILES segment.
Files
/usr/share/dict/words
the dictionary
/usr/share/dict/web2
the alternative dictionary
Examples
sort -d /etc/passwd -o /tmp/look.dict look -t: root:foobar /tmp/look.dict
Releases
19 releases since Debian 1.1 (Buzz); the text changed 9 times.
--alphanum since Debian 10 (Buster);
--alternative since Debian 11 (Bullseye);
--help since Debian 11 (Bullseye);
--ignore-case since Debian 10 (Buster);
--terminate since Debian 10 (Buster);
--version since Debian 11 (Bullseye);
-V since Debian 11 (Bullseye);
-a since Debian 11 (Bullseye);
-h since Debian 11 (Bullseye).
--binary until Debian 10 (Buster);
-b until Debian 10 (Buster).