Is there any utility like grep or even uniq but for inexact search, or I should write it myself?

I mean it will look at 90% (number may vary) matching, or something like that. For example I have file with several strings:


In this case such utility should return the first three string or say they are similar. Of course I don't know any pattern of file's content like in case with grep or uniq.

  • This is very data set specific. For example, is Mary like Marie, or is ABC like BCD? Can you give a real world example of your data? May 23, 2012 at 21:52

1 Answer 1


agrep or tre-grep will do what you're asking; they're "approximate" regex matching/grep. For more information, also see the Wikipedia article.

% tre-agrep --help | head             (05-23 16:53)
Usage: tre-agrep [OPTION]... PATTERN [FILE]...
Searches for approximate matches of PATTERN in each FILE or standard input.
Example: `tre-agrep -2 optimize foo.txt' outputs all lines in file `foo.txt'     that
match "optimize" within two errors.  E.g. lines which contain "optimise",
"optmise", and "opitmize" all match.

Regexp selection and interpretation:
  -e, --regexp=PATTERN      use PATTERN as a regular expression
  -i, --ignore-case         ignore case distinctions
  -k, --literal             PATTERN is a literal string

% agrep  | head                       (05-23 16:53)
usage: agrep [-@#abcdehiklnoprstvwxyBDGIMSV] [-f patternfile] [-H dir] pattern [files]

summary of frequently used options:
(For a more detailed listing see 'man agrep'.)
-#: find matches with at most # errors
-c: output the number of matched records
-d: define record delimiter
-h: do not output file names
-i: case-insensitive search, e.g., 'a' = 'A'
-l: output the names of files that contain a match
-n: output record prefixed by record number
-v: output those records that have no matches
-w: pattern has to match as a word, e.g., 'win' will not match 'wind'
-B: best match mode. find the closest matches to the pattern
-G: output the files that contain a match
-H 'dir': the cast-dictionary is located in directory 'dir'
  • That's exactly the thing I'm looking for. Thank you.
    – rush
    May 23, 2012 at 22:38

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