10-15-2009
Hello, I apologize if the message was unclear.
The problem is: I want to use the following advanced regular expression syntax "(?:)" which represents grouping without backreference.
Related information: From what I read GNU Grep supports the advanced syntax.
Support: I've used "()" which is grouping with backreference.
My goal isn't to solve any particular problem really. I'm new to the unix enviroment and right now I'm trying to learn as much about grep and regular expressions as possible. I understand that the advanced syntax with grep is likely going to be academic only since I would find piping into other programs simpler (sed/awk).
Summary: Can I use the syntax "(?:)" with GNU Grep 2.5.1?
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REGEXP(6) Games Manual REGEXP(6)
NAME
regexp - regular expression notation
DESCRIPTION
A regular expression specifies a set of strings of characters. A member of this set of strings is said to be matched by the regular
expression. In many applications a delimiter character, commonly bounds a regular expression. In the following specification for regular
expressions the word `character' means any character (rune) but newline.
The syntax for a regular expression e0 is
e3: literal | charclass | '.' | '^' | '$' | '(' e0 ')'
e2: e3
| e2 REP
REP: '*' | '+' | '?'
e1: e2
| e1 e2
e0: e1
| e0 '|' e1
A literal is any non-metacharacter, or a metacharacter (one of .*+?[]()|^$), or the delimiter preceded by
A charclass is a nonempty string s bracketed [s] (or [^s]); it matches any character in (or not in) s. A negated character class never
matches newline. A substring a-b, with a and b in ascending order, stands for the inclusive range of characters between a and b. In s,
the metacharacters an initial and the regular expression delimiter must be preceded by a other metacharacters have no special meaning and
may appear unescaped.
A matches any character.
A matches the beginning of a line; matches the end of the line.
The REP operators match zero or more (*), one or more (+), zero or one (?), instances respectively of the preceding regular expression e2.
A concatenated regular expression, e1e2, matches a match to e1 followed by a match to e2.
An alternative regular expression, e0|e1, matches either a match to e0 or a match to e1.
A match to any part of a regular expression extends as far as possible without preventing a match to the remainder of the regular expres-
sion.
SEE ALSO
awk(1), ed(1), sam(1), sed(1), regexp(2)
REGEXP(6)