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LOOK(1) General Commands Manual LOOK(1)

NAME

lookdisplay lines beginning with a given string

SYNOPSIS

look [-bdf] [-t termchar] string [file ...]

DESCRIPTION

The look utility displays any lines in file which contain string as a prefix.
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.
The following options are available:
-b
Use a binary search on the given word list. If you are ignoring case with -f or ignoring non-alphanumeric characters with -d, the file must be sorted in the same way. Please note that these options are the default if no filename is given. See sort(1) for more information on sorting files.
-d
Dictionary character set and order, i.e., only alphanumeric characters are compared.
-f
Ignore the case of alphabetic characters.
-t
Specify a string termination character, i.e., only the characters in string up to and including the first occurrence of termchar are compared.

ENVIRONMENT

The LANG, LC_ALL and LC_CTYPE environment variables affect the execution of the look utility. Their effect is described in environ(7).

FILES

/usr/share/dict/words
the dictionary

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.

COMPATIBILITY

The original manual page stated that tabs and blank characters participated in comparisons when the -d option was specified. This was incorrect and the current man page matches the historic implementation.
look uses a linear search by default instead of a binary search, which is what most other implementations use by default.

SEE ALSO

grep(1), sort(1)

HISTORY

A look utility appeared in Version 7 AT&T UNIX.

BUGS

Lines are not compared according to the current locale's collating order. Input files must be sorted with LC_COLLATE set to ‘C’.
July 17, 2004 Linux 3.16.0-4-amd64