VGREP(1)						      General Commands Manual							  VGREP(1)

NAME

       vgrep, vegrep, vfgrep - print lines matching a pattern

SYNOPOSIS

       vgrep [ vbind-options ] [ -[[AB] ]num ] [ -[CEFGVBchilnsvwx] ] [ -e ] pattern | -ffile ] [ names...  ]

DESCRIPTION

       Vgrep  is  GNU grep with a patch to access AtFS version objects.  Vgrep searches the files and AtFS version objects listed in the arguments
       (or standard input if no names are given, or the name - is given) for lines containing a match to the given  pattern.   By  default,  vgrep
       prints the matching lines.

       There are three major variants of vgrep, controlled by the following options.
       -G     Interpret pattern as a basic regular expression (see below).  This is the default.
       -E     Interpret pattern as an extended regular expression (see below).
       -F     Interpret pattern as a list of fixed strings, separated by newlines, any of which is to be matched.
       In  addition,  two  variant programs vegrep and vfgrep are available.  Vegrep is similar (but not identical) to vgrep -E, and is compatible
       with the historical Unix egrep.	Vfgrep is the same as vgrep -F.

       Vgrep understands the standard version binding options of the Shape toolkit.  The names on the command line are replaced by the appropriate
       version IDs of the selected version object.

       The  vbind-options are shapeTools' standard options for version binding.  A description of these options can be found in the manual page of
       vbind(1).

       All variants of vgrep understand the following options:
       -num   Matches will be printed with num lines of leading and trailing context.  However, vgrep will never print any given  line	more  than
	      once.
       -A num Print num lines of trailing context after matching lines.
       -B num Print num lines of leading context before matching lines.
       -C     Equivalent to -2.
       -V     Print the version number of vgrep to standard error.  This version number should be included in all bug reports (see below).
       -b     Print the byte offset within the input file before each line of output.
       -c     Suppress	normal	output;  instead  print a count of matching lines for each input file.	With the -v option (see below), count non-
	      matching lines.
       -e pattern
	      Use pattern as the pattern; useful to protect patterns beginning with -.
       -f file
	      Obtain the pattern from file.
       -h     Suppress the prefixing of filenames on output when multiple files are searched.
       -i     Ignore case distinctions in both the pattern and the input files.
       -L     Suppress normal output; instead print the name of each input file from which no output would normally have been printed.
       -l     Suppress normal output; instead print the name of each input file from which output would normally have been printed.
       -n     Prefix each line of output with the line number within its input file.
       -q     Quiet; suppress normal output.
       -s     Suppress error messages about nonexistent or unreadable files.
       -v     Invert the sense of matching, to select non-matching lines.
       -w     Select only those lines containing matches that form whole words.  The test is that the matching substring must  either  be  at  the
	      beginning of the line, or preceded by a non-word constituent character.  Similarly, it must be either at the end of the line or fol-
	      lowed by a non-word constituent character.  Word-constituent characters are letters, digits, and the underscore.
       -x     Select only those matches that exactly match the whole line.

REGULAR EXPRESSIONS

       A regular expression is a pattern that describes a set of strings.  Regular expressions are constructed analagously to  arithmetic  expres-
       sions, by using various operators to combine smaller expressions.

       Vgrep  understands two different versions of regular expression syntax: ``basic'' and ``extended.''  In GNU grep, there is no difference in
       available functionality using either syntax.  In other implementations,	basic  regular	expressions  are  less	powerful.   The  following
       description applies to extended regular expressions; differences for basic regular expressions are summarized afterwards.

       The fundamental building blocks are the regular expressions that match a single character.  Most characters, including all letters and dig-
       its, are regular expressions that match themselves.  Any metacharacter with special meaning may be quoted by preceding it with a backslash.

       A list of characters enclosed by [ and ] matches any single character in that list; if the first character of the list is the caret ^  then
       it  matches  any  character  not in the list.  For example, the regular expression [0123456789] matches any single digit.  A range of ASCII
       characters may be specified by giving the first and last characters, separated by a hyphen.  Finally, certain named classes  of	characters
       are  predefined.   Their  names	are  self  explanatory,  and  they  are  [:alnum:], [:alpha:], [:cntrl:], [:digit:], [:graph:], [:lower:],
       [:print:], [:punct:], [:space:], [:upper:], and [:xdigit:].  For example, [[:alnum:]] means [0-9A-Za-z], except the latter form	is  depen-
       dent  upon the ASCII character encoding, whereas the former is portable.  (Note that the brackets in these class names are part of the sym-
       bolic names, and must be included in addition to the brackets delimiting the bracket list.)  Most metacharacters lose their special meaning
       inside lists.  To include a literal ] place it first in the list.  Similarly, to include a literal ^ place it anywhere but first.  Finally,
       to include a literal - place it last.

       The period .  matches any single character.  The symbol w is a synonym for [[:alnum:]] and W is a synonym for [^[:alnum]].

       The caret ^ and the dollar sign $ are metacharacters that respectively match the empty string at the beginning and end of a line.  The sym-
       bols  < and > respectively match the empty string at the beginning and end of a word.	The symbol  matches the empty string at the edge
       of a word, and B matches the empty string provided it's not at the edge of a word.

       A regular expression matching a single character may be followed by one of several repetition operators:
       ?      The preceding item is optional and matched at most once.
       *      The preceding item will be matched zero or more times.
       +      The preceding item will be matched one or more times.
       {n}    The preceding item is matched exactly n times.
       {n,}   The preceding item is matched n or more times.
       {,m}   The preceding item is optional and is matched at most m times.
       {n,m}  The preceding item is matched at least n times, but not more than m times.

       Two regular expressions may be concatenated; the resulting regular expression matches any string formed	by  concatenating  two	substrings
       that respectively match the concatenated subexpressions.

       Two  regular  expressions may be joined by the infix operator |; the resulting regular expression matches any string matching either subex-
       pression.

       Repetition takes precedence over concatenation, which in turn takes precedence over alternation.  A whole subexpression may be enclosed	in
       parentheses to override these precedence rules.

       The  backreference  
,	where  n is a single digit, matches the substring previously matched by the nth parenthesized subexpression of the
       regular expression.

       In basic regular expressions the metacharacters ?, +, {, |, (, and ) lose their special meaning; instead use the backslashed  versions  ?,
       +, {, |, (, and ).

       In vegrep the metacharacter { loses its special meaning; instead use {.

DIAGNOSTICS

       Normally,  exit	status	is 0 if matches were found, and 1 if no matches were found.  (The -v option inverts the sense of the exit status.)
       Exit status is 2 if there were syntax errors in the pattern, inaccessible input files, or other system errors.

EXAMPLES

       Grep for ``foo'' in version 1.43 of smile.c:

	      vgrep foo smile.c[1.43]

       Grep for ``foo'' in the last version of smile.c (last saved version or busy file, if available):

	      vgrep -last foo smile.c

       Grep for ``foo'' in all versions of C files that have been created since February 14 1993:

	      vgrep -since 14.2.93 foo *.c

       Grep for ``foo'' in all versions carrying the symbolic name ``Release-2.3'':

	      vgrep foo *[Release-2.3]

SEE ALSO

       emacs(1), ed(1), sh(1), vbind(1), atread(3), GNU Emacs Manual

BUGS

       Email bug reports to bug-gnu-utils@prep.ai.mit.edu.  Be sure to include the word ``grep'' somewhere in the ``Subject:'' field.

       Large repetition counts in the {m,n} construct may cause vgrep to use lots of memory.  In addition, certain other obscure  regular  expres-
       sions require exponential time and space, and may cause vgrep to run out of memory.

       Backreferences are very slow, and may require exponential time.

GNU Project							 1992 September 10							  VGREP(1)