agrep

AGREP(1)                    General Commands Manual                   AGREP(1)



NAME
       agrep - search a file for a string or regular expression, with
       approximate matching capabilities

SYNOPSIS
       agrep [ -#cdehiklnpstvwxBDGIS ] pattern [ -f patternfile ] [
       filename... ]

DESCRIPTION
       agrep searches the input filenames (standard input is the default, but
       see a warning under LIMITATIONS) for records containing strings which
       either exactly or approximately match a pattern.  A record is by
       default a line, but it can be defined differently using the -d option
       (see below).  Normally, each record found is copied to the standard
       output.  Approximate matching allows finding records that contain the
       pattern with several errors including substitutions, insertions, and
       deletions.  For example, Massechusets matches Massachusetts with two
       errors (one substitution and one insertion).  Running agrep -2
       Massechusets foo outputs all lines in foo containing any string with at
       most 2 errors from Massechusets.

       agrep supports many kinds of queries including arbitrary wild cards,
       sets of patterns, and in general, regular expressions.  See PATTERNS
       below.  It supports most of the options supported by the grep family
       plus several more (but it is not 100% compatible with grep).  For more
       information on the algorithms used by agrep see Wu and Manber, "Fast
       Text Searching With Errors," Technical report #91-11, Department of
       Computer Science, University of Arizona, June 1991 (available by
       anonymous ftp from cs.arizona.edu in agrep/agrep.ps.1), and Wu and
       Manber, "Agrep -- A Fast Approximate Pattern Searching Tool", To appear
       in USENIX Conference 1992 January (available by anonymous ftp from
       cs.arizona.edu in agrep/agrep.ps.2).

       As with the rest of the grep family, the characters `$', `^', `', `[',
       `]', `^', `|', `(', `)', `!', and `\' can cause unexpected results when
       included in the pattern, as these characters are also meaningful to the
       shell.  To avoid these problems, one should always enclose the entire
       pattern argument in single quotes, i.e., 'pattern'.  Do not use double
       quotes (").

       When agrep is applied to more than one input file, the name of the file
       is displayed preceding each line which matches the pattern.  The
       filename is not displayed when processing a single file, so if you
       actually want the filename to appear, use /dev/null as a second file in
       the list.

OPTIONS
       -#     # is a non-negative integer (at most 8) specifying the maximum
              number of errors permitted in finding the approximate matches
              (defaults to zero).  Generally, each insertion, deletion, or
              substitution counts as one error.  It is possible to adjust the
              relative cost of insertions, deletions and substitutions (see -I
              -D and -S options).

       -c     Display only the count of matching records.

       -d 'delim'
              Define delim to be the separator between two records.  The
              default value is '$', namely a record is by default a line.
              delim can be a string of size at most 8 (with possible use of ^
              and $), but not a regular expression.  Text between two delim's,
              before the first delim, and after the last delim is considered
              as one record.  For example, -d '$$' defines paragraphs as
              records and -d '^From ' defines mail messages as records.  agrep
              matches each record separately.  This option does not currently
              work with regular expressions.

       -e pattern
              Same as a simple pattern argument, but useful when the pattern
              begins with a `-'.

       -f patternfile
              patternfile contains a set of (simple) patterns.  The output is
              all lines that match at least one of the patterns in
              patternfile.  Currently, the -f option works only for exact
              match and for simple patterns (any meta symbol is interpreted as
              a regular character); it is compatible only with -c, -h, -i, -l,
              -s, -v, -w, and -x options.  see LIMITATIONS for size bounds.

       -h     Do not display filenames.

       -i     Case-insensitive search — e.g., "A" and "a" are considered
              equivalent.

       -k     No symbol in the pattern is treated as a meta character.  For
              example, agrep -k 'a(b|c)*d' foo will find the occurrences of
              a(b|c)*d in foo whereas agrep 'a(b|c)*d' foo will find
              substrings in foo that match the regular expression 'a(b|c)*d'.

       -l     List only the files that contain a match.  This option is useful
              for looking for files containing a certain pattern.  For
              example, " agrep -l 'wonderful'  * " will list the names of
              those files in current directory that contain the word
              'wonderful'.

       -n     Each line that is printed is prefixed by its record number in
              the file.

       -p     Find records in the text that contain a supersequence of the
              pattern.  For example,
               agrep -p DCS foo will match "Department of Computer Science."

       -s     Work silently, that is, display nothing except error messages.
              This is useful for checking the error status.

       -t     Output the record starting from the end of delim to (and
              including) the next delim.  This is useful for cases where delim
              should come at the end of the record.

       -v     Inverse mode — display only those records that do not contain
              the pattern.

       -w     Search for the pattern as a word — i.e., surrounded by non-
              alphanumeric characters.  The non-alphanumeric must surround the
              match;  they cannot be counted as errors.  For example, agrep -w
              -1 car will match cars, but not characters.

       -x     The pattern must match the whole line.

       -y     Used with -B option. When -y is on, agrep will always output the
              best matches without giving a prompt.

       -B     Best match mode.  When -B is specified and no exact matches are
              found, agrep will continue to search until the closest matches
              (i.e., the ones with minimum number of errors) are found, at
              which point the following message will be shown: "the best match
              contains x errors, there are y matches, output them? (y/n)" The
              best match mode is not supported for standard input, e.g.,
              pipeline input.  When the -#, -c, or -l options are specified,
              the -B option is ignored.  In general, -B may be slower than -#,
              but not by very much.

       -Dk    Set the cost of a deletion to k (k is a positive integer).  This
              option does not currently work with regular expressions.

       -G     Output the files that contain a match.

       -Ik    Set the cost of an insertion to k (k is a positive integer).
              This option does not currently work with regular expressions.

       -Sk    Set the cost of a substitution to k (k is a positive integer).
              This option does not currently work with regular expressions.

PATTERNS
       agrep supports a large variety of patterns, including simple strings,
       strings with classes of characters, sets of strings, wild cards, and
       regular expressions.

       Strings
              any sequence of characters, including the special symbols `^'
              for beginning of line and `$' for end of line.  The special
              characters listed above ( `$', `^', `', `[', `^', `|', `(',
              `)', `!', and `\' ) should be preceded by `\' if they are to be
              matched as regular characters.  For example, \^abc\\ corresponds
              to the string ^abc\, whereas ^abc corresponds to the string abc
              at the beginning of a line.

       Classes of characters
              a list of characters inside [] (in order) corresponds to any
              character from the list.  For example, [a-ho-z] is any character
              between a and h or between o and z.  The symbol `^' inside []
              complements the list.  For example, [^i-n] denote any character
              in the character set except character 'i' to 'n'.  The symbol
              `^' thus has two meanings, but this is consistent with egrep.
              The symbol `.' (don't care) stands for any symbol (except for
              the newline symbol).

       Boolean operations
              agrep supports an `and' operation `;' and an `or' operation `,',
              but not a combination of both.  For example, 'fast;network'
              searches for all records containing both words.

       Wild cards
              The symbol '#' is used to denote a wild card.  # matches zero or
              any number of arbitrary characters.  For example, ex#e matches
              example.  The symbol # is equivalent to .* in egrep.  In fact,
              .* will work too, because it is a valid regular expression (see
              below), but unless this is part of an actual regular expression,
              # will work faster.

       Combination of exact and approximate matching
              any pattern inside angle brackets <> must match the text exactly
              even if the match is with errors.  For example, <mathemat>ics
              matches mathematical with one error (replacing the last s with
              an a), but mathe<matics> does not match mathematical no matter
              how many errors we allow.

       Regular expressions
              The syntax of regular expressions in agrep is in general the
              same as that for egrep.  The union operation `|', Kleene closure
              `*', and parentheses () are all supported.  Currently '+' is not
              supported.  Regular expressions are currently limited to
              approximately 30 characters (generally excluding meta
              characters).  Some options (-d, -w, -f, -t, -x, -D, -I, -S) do
              not currently work with regular expressions.  The maximal number
              of errors for regular expressions that use '*' or '|' is 4.

EXAMPLES
       agrep -2 -c ABCDEFG foo
              gives the number of lines in file foo that contain ABCDEFG
              within two errors.

       agrep -1 -D2 -S2 'ABCD#YZ' foo
              outputs the lines containing ABCD followed, within arbitrary
              distance, by YZ, with up to one additional insertion (-D2 and
              -S2 make deletions and substitutions too "expensive").

       agrep -5 -p abcdefghij /path/to/dictionary/words
              outputs the list of all words containing at least 5 of the first
              10 letters of the alphabet in order.  (Try it:  any list
              starting with academia and ending with sacrilegious must mean
              something!)

       agrep -1 'abc[0-9](de|fg)*[x-z]' foo
              outputs the lines containing, within up to one error, the string
              that starts with abc followed by one digit, followed by zero or
              more repetitions of either de or fg, followed by either x, y, or
              z.

       agrep -d '^From ' 'breakdown;internet' mbox
              outputs all mail messages (the pattern '^From ' separates mail
              messages in a mail file) that contain keywords 'breakdown' and
              'internet'.

       agrep -d '$$' -1 '<word1> <word2>' foo
              finds all paragraphs that contain word1 followed by word2 with
              one error in place of the blank.  In particular, if word1 is the
              last word in a line and word2 is the first word in the next
              line, then the space will be substituted by a newline symbol and
              it will match.  Thus, this is a way to overcome separation by a
              newline.  Note that -d '$$' (or another delim which spans more
              than one line) is necessary, because otherwise agrep searches
              only one line at a time.

       agrep '^agrep' <this manual>
              outputs all the examples of the use of agrep in this man pages.

SEE ALSO
       ed(1), ex(1), grep(1V), sh(1), csh(1).

BUGS/LIMITATIONS
       Any bug reports or comments will be appreciated!  Please mail them to
       sw@cs.arizona.edu or udi@cs.arizona.edu

       Regular expressions do not support the '+' operator (match 1 or more
       instances of the preceding token).  These can be searched for by using
       this syntax in the pattern:

          'pattern(pattern)*'

       (search for strings containing one instance of the pattern, followed by
       0 or more instances of the pattern).

       The following can cause an infinite loop: agrep pattern * >
       output_file.  If the number of matches is high, they may be deposited
       in output_file before it is completely read leading to more matches of
       the pattern within output_file (the matches are against the whole
       directory).  It's not clear whether this is a "bug" (grep will do the
       same), but be warned.

       The maximum size of the patternfile is limited to be 250Kb, and the
       maximum number of patterns is limited to be 30,000.

       Standard input is the default if no input file is given.  However, if
       standard input is keyed in directly (as opposed to through a pipe, for
       example) agrep may not work for some non-simple patterns.

       There is no size limit for simple patterns.  More complicated patterns
       are currently limited to approximately 30 characters.  Lines are
       limited to 1024 characters.  Records are limited to 48K, and may be
       truncated if they are larger than that.  The limit of record length can
       be changed by modifying the parameter Max_record in agrep.h.

DIAGNOSTICS
       Exit status is 0 if any matches are found, 1 if none, 2 for syntax
       errors or inaccessible files.

AUTHORS
       Sun Wu and Udi Manber, Department of Computer Science, University of
       Arizona, Tucson, AZ 85721.  {sw|udi}@cs.arizona.edu.





                                 Jan 17, 1992                         AGREP(1)