EGREP(1)            RISC/os Reference Manual             EGREP(1)



NAME
     egrep - search a file for a pattern using full regular
          expressions

SYNOPSIS
     egrep [options] full regular expression [file ...]

DESCRIPTION
     egrep (expression grep) searches files for a pattern of
     characters and prints all lines that contain that pattern.
     egrep uses full regular expressions (expressions that have
     string values that use the full set of alphanumeric and spe-
     cial characters) to match the patterns.  It uses a fast
     deterministic algorithm that sometimes needs exponential
     space.

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

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

     Be careful using the characters $, *, [, ^, |, (, ), and \
     in full regular expression, because they are also meaningful
     to the shell.  It is safest to enclose the entire full regu-
     lar expression in single quotes '...'.

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

     If no files are specified, egrep assumes standard input.
     Normally, each line found is copied to the standard output.
     The file name is printed before each line found if there is
     more than one input file.

     Command line options are:

     -b    Precede each line by the block number (512-byte block)
           on which it was found.  This can be useful in locating
           block numbers by context (first block is 0).
     -c    Print only a count of the lines that contain the pat-
           tern.
     -i    Ignore upper/lower case distinction during comparis-
           ons.



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EGREP(1)            RISC/os Reference Manual             EGREP(1)



     -h    Suppress printing of filenames when searching multiple
           files.
     -l    Print the names of files with matching lines once,
           separated by new-lines.  Does not repeat the names of
           files when the pattern is found more than once.
     -n    Precede each line by its line number in the file
           (first line is 1).
     -v    Print all lines except those that contain the pattern.
     -e special_expression
           Search for a special expression (full regular expres-
           sion that begins with a -).
     -f file
           Take the list of full regular expressions from file.

INTERNATIONAL FUNCTIONALITY
     egrep can process characters from supplementary code sets.
     In regular expressions, searches are performed on charac-
     ters, not on individual bytes.

     The -i option, ignore upper/lower case distinction during
     comparisons, is valid for single byte characters only.

SEE ALSO
     ed(1), fgrep(1), grep(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).

NOTES
     Ideally there should be only one grep command, but there is
     not a single algorithm that spans a wide enough range of
     space-time tradeoffs.  Lines are limited to BUFSIZ charac-
     ters; longer lines are truncated. BUFSIZ is defined in
     /usr/include/stdio.h.



















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