


      GREP(1)                     (UNIX 5.2)                    GREP(1)



      NAME
           grep, egrep, fgrep - search a file for a pattern

      SYNTAX
           grep [ options ] expression [ files ]

           egrep [ options ] [ expression ] [ files ]

           fgrep [ options ] [ strings ] [ files ]

      DESCRIPTION
           Commands of the grep family search the input files (standard
           input default) for lines matching a pattern.  Normally, each
           line found is copied to the standard output.  Grep patterns
           are limited regular expressions in the style of ed(1); it
           uses a compact non-deterministic algorithm.  Egrep patterns
           are full regular expressions; it uses a fast deterministic
           algorithm that sometimes needs exponential space.  Fgrep
           patterns are fixed strings; it is fast and compact.  The
           following options are recognized:

           -v    All lines but those matching are printed.
           -x    (Exact) only lines matched in their entirety are
                 printed (fgrep only).
           -c    Only a count of matching lines is printed.
           -i    Ignore upper/lower case distinction during
                 comparisons.
           -l    Only the names of files with matching lines are listed
                 (once), separated by new-lines.
           -n    Each line is preceded by its relative line number in
                 the file.
           -b    Each line is preceded by the block number on which it
                 was found.  This is sometimes useful in locating disk
                 block numbers by context. (a block is 1024 bytes.)
           -s    The error messages produced for nonexistent or
                 unreadable files are suppressed (grep only).
           -e expression
                 Same as a simple expression argument, but useful when
                 the expression begins with a - (does not work with
                 grep).
           -f file
                 The regular expression (egrep) or strings list (fgrep)
                 is taken from the file.

           In all cases, the file name is output if there is more than
           one input file.  Care should be taken when using the
           characters $, *, [, ^, |, (, ), and \ in expression, because
           they are also meaningful to the shell.  It is safest to
           enclose the entire expression argument in single quotes
           '...'.

           Fgrep searches for lines that contain one of the strings



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      GREP(1)                     (UNIX 5.2)                    GREP(1)



           separated by new-lines.

           Egrep accepts regular expressions as in ed(1), except for \(
           and \), with the addition of:

           1.    A regular expression followed by + matches one or more
                 occurrences of the regular expression.
           2.    A regular expression followed by ? matches 0 or 1
                 occurrences of the regular expression.
           3.    Two regular expressions separated by | or by a new-
                 line match strings that are matched by either.
           4.    A regular expression may be enclosed in parentheses ()
                 for grouping.

           The order of precedence of operators is [], then *?+, then
           concatenation, then | and new-line.

      SEE ALSO
           ed(1), sed(1), sh(1).

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

      BUGS
           Ideally there should be only one grep, but we do not know a
           single algorithm that spans a wide enough range of space-
           time tradeoffs.
           Lines are limited to BUFSIZ characters; longer lines are
           truncated.  (BUFSIZ is defined in /usr/include/stdio.h.)
           Egrep does not recognize ranges, such as [a-z], in character
           classes.
           If there is a line with embedded nulls, grep will only match
           up to the first null; if it matches, it will print the
           entire line.



















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