LOOK(1) - Linux man page online | User commands

Display lines beginning with a given string.

July 17, 2004
LOOK(1) BSD General Commands Manual LOOK(1)


look — display lines beginning with a given string


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


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 charac‐ ters are compared and the case of alphabetic characters is ignored. The following options are available: -b, --binary 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, --alphanum Dictionary character set and order, i.e., only alphanumeric characters are compared. -f, --ignore-case Ignore the case of alphabetic characters. -t, --terminate termchar Specify a string termination character, i.e., only the characters in string up to and including the first occurrence of termchar are compared.


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


/usr/share/dict/words the dictionary


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.


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. The -a and --alternative flags are ignored for compatibility.


grep(1), sort(1)


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


Lines are not compared according to the current locale's collating order. Input files must be sorted with LC_COLLATE set to ‘C’.
BSD July 17, 2004 BSD
This manual Reference Other manuals
look(1) referred by ascii(1plan9) | ispell(1) | italian(5) | rs(1) | sort(1plan9)
refer to environ(7) | grep(1) | sort(1)
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