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  followed  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 expressions, 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  digits,  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 dependent upon the ASCII character
       encoding, whereas the former is portable.  (Note that the brackets in these class names are part  of  the
       symbolic  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 symbols \< and \> respectively match the empty string at the  beginning
       and  end  of  a  word.   The symbol \b 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 subexpression.

       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  \n,  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 expressions require exponential time and space, and may cause vgrep to run
       out of memory.

       Backreferences are very slow, and may require exponential time.