Agrep is a tool for fast text searching allowing errors.

The three most significant features of agrep that are not supported by
the grep family are 
1) the ability to search for approximate patterns;
    for example, "agrep -2 homogenos foo" will find homogeneous as well 
    as any other word that can be obtained from homogenos with at most 
    2 substitutions, insertions, or deletions.
    "agrep -B homogenos foo" will generate a message of the form
    best match has 2 errors, there are 5 matches, output them? (y/n)
2) agrep is record oriented rather than just line oriented;  a record
    is by default a line, but it can be user defined;
    for example, "agrep -d '^From ' 'pizza' mbox"
    outputs all mail messages that contain the keyword "pizza".
    Another example:  "agrep -d '$$' pattern foo" will output all
    paragraphs (separated by an empty line) that contain pattern.
3) multiple patterns with AND (or OR) logic queries.   
    For example, "agrep -d '^From ' 'burger,pizza' mbox" 
    outputs all mail messages containing at least one of the 
    two keywords (, stands for OR).
    "agrep -d '^From ' 'good;pizza' mbox" outputs all mail messages
    containing both keywords.

Putting these options together one can ask queries like

agrep -d '$$' -2 '<CACM>;TheAuthor;Curriculum;<198[5-9]>' bib

which outputs all paragraphs referencing articles in CACM between 
1985 and 1989 by TheAuthor dealing with curriculum.  
Two errors are allowed, but they cannot be in either CACM or the year 
(the <> brackets forbid errors in the pattern between them).  

Two technical papers describing agrep are available as:

	agrep.ps.1 is a technical report from June 1991 describing the
	design and implementation of agrep
		ftp://ftp.cs.arizona.edu/agrep/agrep.ps.1.Z

	agrep.ps.2 is a copy of the paper as appeared in the 1992 Winter
	USENIX conference.
		ftp://ftp.cs.arizona.edu/agrep/agrep.ps.2.Z

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