look

uses binary search to find lines beginning with a given prefix in a sorted file

TLDR

Find lines starting with prefix

$ look [prefix] [path/to/file]

Search case-insensitive alphanumeric only

$ look -f -d [prefix] [path/to/file]

Specify termination character

$ look -t [char] [prefix] [path/to/file]

Search in system dictionary

$ look [prefix]

SYNOPSIS

look [options] string [file ...]

look uses binary search to find lines beginning with a given prefix in a sorted file. Without a file argument, it searches the system dictionary (/usr/share/dict/words), and automatically applies case-insensitive and alphanumeric-only comparison.

PARAMETERS

-f, --ignore-case

Ignore the case of alphabetic characters

-d, --alphanum

Only compare alphanumeric characters (dictionary order)

-t, --terminate CHAR

Specify a string termination character; only the characters in the prefix up to and including the first occurrence of CHAR are compared

CAVEATS

Requires input file to be sorted. For correct results, the file must be sorted with LC_COLLATE set to 'C', as look does not compare according to the current locale's collating order. When no file is specified, -f and -d are applied implicitly. Exits 0 if lines were found, 1 if no lines were found, and >1 on error.