--- /dev/null
+@menu
+* awk regular expression syntax::
+* egrep regular expression syntax::
+* ed regular expression syntax::
+* emacs regular expression syntax::
+* gnu-awk regular expression syntax::
+* grep regular expression syntax::
+* posix-awk regular expression syntax::
+* posix-basic regular expression syntax::
+* posix-egrep regular expression syntax::
+* posix-extended regular expression syntax::
+* posix-minimal-basic regular expression syntax::
+* sed regular expression syntax::
+@end menu
+
+@node awk regular expression syntax
+@subsection @samp{awk} regular expression syntax
+
+
+The character @samp{.} matches any single character except the null character.
+
+
+@table @samp
+
+@item +
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item ?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item \+
+matches a @samp{+}
+@item \?
+matches a @samp{?}.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are invalid. Within square brackets, @samp{\} can be used to quote the following character. Character classes are not supported, so for example you would need to use @samp{[0-9]} instead of @samp{[[:digit:]]}.
+
+GNU extensions are not supported and so @samp{\w}, @samp{\W}, @samp{\<}, @samp{\>}, @samp{\b}, @samp{\B}, @samp{\`}, and @samp{\'} match @samp{w}, @samp{W}, @samp{<}, @samp{>}, @samp{b}, @samp{B}, @samp{`}, and @samp{'} respectively.
+
+Grouping is performed with parentheses @samp{()}. An unmatched @samp{)} matches just itself. A backslash followed by a digit matches that digit.
+
+The alternation operator is @samp{|}.
+
+The characters @samp{^} and @samp{$} always represent the beginning and end of a string respectively, except within square brackets. Within brackets, @samp{^} can be used to invert the membership of the character class being specified.
+
+@samp{*}, @samp{+} and @samp{?} are special at any point in a regular expression except:
+@enumerate
+
+@item At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{(}
+@item After the alternation operator @samp{|}
+
+@end enumerate
+
+
+
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node egrep regular expression syntax
+@subsection @samp{egrep} regular expression syntax
+
+
+The character @samp{.} matches any single character except newline.
+
+
+@table @samp
+
+@item +
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item ?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item \+
+matches a @samp{+}
+@item \?
+matches a @samp{?}.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are ignored. Within square brackets, @samp{\} is taken literally. Character classes are supported; for example @samp{[[:digit:]]} will match a single decimal digit. Non-matching lists @samp{[^@dots{}]} do not ever match newline.
+
+GNU extensions are supported:
+@enumerate
+
+@item @samp{\w} matches a character within a word
+
+@item @samp{\W} matches a character which is not within a word
+
+@item @samp{\<} matches the beginning of a word
+
+@item @samp{\>} matches the end of a word
+
+@item @samp{\b} matches a word boundary
+
+@item @samp{\B} matches characters which are not a word boundary
+
+@item @samp{\`} matches the beginning of the whole input
+
+@item @samp{\'} matches the end of the whole input
+
+@end enumerate
+
+
+Grouping is performed with parentheses @samp{()}. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{(}.
+
+The alternation operator is @samp{|}.
+
+The characters @samp{^} and @samp{$} always represent the beginning and end of a string respectively, except within square brackets. Within brackets, @samp{^} can be used to invert the membership of the character class being specified.
+
+The characters @samp{*}, @samp{+} and @samp{?} are special anywhere in a regular expression.
+
+
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node ed regular expression syntax
+@subsection @samp{ed} regular expression syntax
+
+
+The character @samp{.} matches any single character except the null character.
+
+
+@table @samp
+
+@item \+
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item \?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item + and ?
+match themselves.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are invalid. Within square brackets, @samp{\} is taken literally. Character classes are supported; for example @samp{[[:digit:]]} will match a single decimal digit.
+
+GNU extensions are supported:
+@enumerate
+
+@item @samp{\w} matches a character within a word
+
+@item @samp{\W} matches a character which is not within a word
+
+@item @samp{\<} matches the beginning of a word
+
+@item @samp{\>} matches the end of a word
+
+@item @samp{\b} matches a word boundary
+
+@item @samp{\B} matches characters which are not a word boundary
+
+@item @samp{\`} matches the beginning of the whole input
+
+@item @samp{\'} matches the end of the whole input
+
+@end enumerate
+
+
+Grouping is performed with backslashes followed by parentheses @samp{\(}, @samp{\)}. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{\(}.
+
+The alternation operator is @samp{\|}.
+
+The character @samp{^} only represents the beginning of a string when it appears:
+@enumerate
+
+@item
+At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{\(}
+
+@item After the alternation operator @samp{\|}
+
+@end enumerate
+
+
+The character @samp{$} only represents the end of a string when it appears:
+@enumerate
+
+@item At the end of a regular expression
+
+@item Before an close-group, signified by
+@samp{\)}
+@item Before the alternation operator @samp{\|}
+
+@end enumerate
+
+
+@samp{\*}, @samp{\+} and @samp{\?} are special at any point in a regular expression except:
+@enumerate
+
+@item At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{\(}
+@item After the alternation operator @samp{\|}
+
+@end enumerate
+
+
+Intervals are specified by @samp{\@{} and @samp{\@}}. Invalid intervals such as @samp{a\@{1z} are not accepted.
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node emacs regular expression syntax
+@subsection @samp{emacs} regular expression syntax
+
+
+The character @samp{.} matches any single character except newline.
+
+
+@table @samp
+
+@item +
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item ?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item \+
+matches a @samp{+}
+@item \?
+matches a @samp{?}.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are ignored. Within square brackets, @samp{\} is taken literally. Character classes are not supported, so for example you would need to use @samp{[0-9]} instead of @samp{[[:digit:]]}.
+
+GNU extensions are supported:
+@enumerate
+
+@item @samp{\w} matches a character within a word
+
+@item @samp{\W} matches a character which is not within a word
+
+@item @samp{\<} matches the beginning of a word
+
+@item @samp{\>} matches the end of a word
+
+@item @samp{\b} matches a word boundary
+
+@item @samp{\B} matches characters which are not a word boundary
+
+@item @samp{\`} matches the beginning of the whole input
+
+@item @samp{\'} matches the end of the whole input
+
+@end enumerate
+
+
+Grouping is performed with backslashes followed by parentheses @samp{\(}, @samp{\)}. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{\(}.
+
+The alternation operator is @samp{\|}.
+
+The character @samp{^} only represents the beginning of a string when it appears:
+@enumerate
+
+@item
+At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{\(}
+
+@item After the alternation operator @samp{\|}
+
+@end enumerate
+
+
+The character @samp{$} only represents the end of a string when it appears:
+@enumerate
+
+@item At the end of a regular expression
+
+@item Before an close-group, signified by
+@samp{\)}
+@item Before the alternation operator @samp{\|}
+
+@end enumerate
+
+
+@samp{*}, @samp{+} and @samp{?} are special at any point in a regular expression except:
+@enumerate
+
+@item At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{\(}
+@item After the alternation operator @samp{\|}
+
+@end enumerate
+
+
+
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node gnu-awk regular expression syntax
+@subsection @samp{gnu-awk} regular expression syntax
+
+
+The character @samp{.} matches any single character.
+
+
+@table @samp
+
+@item +
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item ?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item \+
+matches a @samp{+}
+@item \?
+matches a @samp{?}.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are invalid. Within square brackets, @samp{\} can be used to quote the following character. Character classes are supported; for example @samp{[[:digit:]]} will match a single decimal digit.
+
+GNU extensions are supported:
+@enumerate
+
+@item @samp{\w} matches a character within a word
+
+@item @samp{\W} matches a character which is not within a word
+
+@item @samp{\<} matches the beginning of a word
+
+@item @samp{\>} matches the end of a word
+
+@item @samp{\b} matches a word boundary
+
+@item @samp{\B} matches characters which are not a word boundary
+
+@item @samp{\`} matches the beginning of the whole input
+
+@item @samp{\'} matches the end of the whole input
+
+@end enumerate
+
+
+Grouping is performed with parentheses @samp{()}. An unmatched @samp{)} matches just itself. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{(}.
+
+The alternation operator is @samp{|}.
+
+The characters @samp{^} and @samp{$} always represent the beginning and end of a string respectively, except within square brackets. Within brackets, @samp{^} can be used to invert the membership of the character class being specified.
+
+@samp{*}, @samp{+} and @samp{?} are special at any point in a regular expression except:
+@enumerate
+
+@item At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{(}
+@item After the alternation operator @samp{|}
+
+@end enumerate
+
+
+
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node grep regular expression syntax
+@subsection @samp{grep} regular expression syntax
+
+
+The character @samp{.} matches any single character except newline.
+
+
+@table @samp
+
+@item \+
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item \?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item + and ?
+match themselves.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are ignored. Within square brackets, @samp{\} is taken literally. Character classes are supported; for example @samp{[[:digit:]]} will match a single decimal digit. Non-matching lists @samp{[^@dots{}]} do not ever match newline.
+
+GNU extensions are supported:
+@enumerate
+
+@item @samp{\w} matches a character within a word
+
+@item @samp{\W} matches a character which is not within a word
+
+@item @samp{\<} matches the beginning of a word
+
+@item @samp{\>} matches the end of a word
+
+@item @samp{\b} matches a word boundary
+
+@item @samp{\B} matches characters which are not a word boundary
+
+@item @samp{\`} matches the beginning of the whole input
+
+@item @samp{\'} matches the end of the whole input
+
+@end enumerate
+
+
+Grouping is performed with backslashes followed by parentheses @samp{\(}, @samp{\)}. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{\(}.
+
+The alternation operator is @samp{\|}.
+
+The character @samp{^} only represents the beginning of a string when it appears:
+@enumerate
+
+@item
+At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{\(}
+
+@item After a newline
+
+@item After the alternation operator @samp{\|}
+
+@end enumerate
+
+
+The character @samp{$} only represents the end of a string when it appears:
+@enumerate
+
+@item At the end of a regular expression
+
+@item Before an close-group, signified by
+@samp{\)}
+@item Before a newline
+
+@item Before the alternation operator @samp{\|}
+
+@end enumerate
+
+
+@samp{\*}, @samp{\+} and @samp{\?} are special at any point in a regular expression except:
+@enumerate
+
+@item At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{\(}
+@item After a newline
+
+@item After the alternation operator @samp{\|}
+
+@end enumerate
+
+
+Intervals are specified by @samp{\@{} and @samp{\@}}. Invalid intervals such as @samp{a\@{1z} are not accepted.
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node posix-awk regular expression syntax
+@subsection @samp{posix-awk} regular expression syntax
+
+
+The character @samp{.} matches any single character except the null character.
+
+
+@table @samp
+
+@item +
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item ?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item \+
+matches a @samp{+}
+@item \?
+matches a @samp{?}.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are invalid. Within square brackets, @samp{\} can be used to quote the following character. Character classes are supported; for example @samp{[[:digit:]]} will match a single decimal digit.
+
+GNU extensions are not supported and so @samp{\w}, @samp{\W}, @samp{\<}, @samp{\>}, @samp{\b}, @samp{\B}, @samp{\`}, and @samp{\'} match @samp{w}, @samp{W}, @samp{<}, @samp{>}, @samp{b}, @samp{B}, @samp{`}, and @samp{'} respectively.
+
+Grouping is performed with parentheses @samp{()}. An unmatched @samp{)} matches just itself. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{(}.
+
+The alternation operator is @samp{|}.
+
+The characters @samp{^} and @samp{$} always represent the beginning and end of a string respectively, except within square brackets. Within brackets, @samp{^} can be used to invert the membership of the character class being specified.
+
+@samp{*}, @samp{+} and @samp{?} are special at any point in a regular expression except the following places, where they are illegal:
+@enumerate
+
+@item At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{(}
+@item After the alternation operator @samp{|}
+
+@end enumerate
+
+
+Intervals are specified by @samp{@{} and @samp{@}}. Invalid intervals such as @samp{a@{1z} are not accepted.
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node posix-basic regular expression syntax
+@subsection @samp{posix-basic} regular expression syntax
+This is a synonym for ed.
+@node posix-egrep regular expression syntax
+@subsection @samp{posix-egrep} regular expression syntax
+
+
+The character @samp{.} matches any single character except newline.
+
+
+@table @samp
+
+@item +
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item ?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item \+
+matches a @samp{+}
+@item \?
+matches a @samp{?}.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are ignored. Within square brackets, @samp{\} is taken literally. Character classes are supported; for example @samp{[[:digit:]]} will match a single decimal digit. Non-matching lists @samp{[^@dots{}]} do not ever match newline.
+
+GNU extensions are supported:
+@enumerate
+
+@item @samp{\w} matches a character within a word
+
+@item @samp{\W} matches a character which is not within a word
+
+@item @samp{\<} matches the beginning of a word
+
+@item @samp{\>} matches the end of a word
+
+@item @samp{\b} matches a word boundary
+
+@item @samp{\B} matches characters which are not a word boundary
+
+@item @samp{\`} matches the beginning of the whole input
+
+@item @samp{\'} matches the end of the whole input
+
+@end enumerate
+
+
+Grouping is performed with parentheses @samp{()}. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{(}.
+
+The alternation operator is @samp{|}.
+
+The characters @samp{^} and @samp{$} always represent the beginning and end of a string respectively, except within square brackets. Within brackets, @samp{^} can be used to invert the membership of the character class being specified.
+
+The characters @samp{*}, @samp{+} and @samp{?} are special anywhere in a regular expression.
+
+Intervals are specified by @samp{@{} and @samp{@}}. Invalid intervals are treated as literals, for example @samp{a@{1} is treated as @samp{a\@{1}
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node posix-extended regular expression syntax
+@subsection @samp{posix-extended} regular expression syntax
+
+
+The character @samp{.} matches any single character except the null character.
+
+
+@table @samp
+
+@item +
+indicates that the regular expression should match one or more occurrences of the previous atom or regexp.
+@item ?
+indicates that the regular expression should match zero or one occurrence of the previous atom or regexp.
+@item \+
+matches a @samp{+}
+@item \?
+matches a @samp{?}.
+@end table
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are invalid. Within square brackets, @samp{\} is taken literally. Character classes are supported; for example @samp{[[:digit:]]} will match a single decimal digit.
+
+GNU extensions are supported:
+@enumerate
+
+@item @samp{\w} matches a character within a word
+
+@item @samp{\W} matches a character which is not within a word
+
+@item @samp{\<} matches the beginning of a word
+
+@item @samp{\>} matches the end of a word
+
+@item @samp{\b} matches a word boundary
+
+@item @samp{\B} matches characters which are not a word boundary
+
+@item @samp{\`} matches the beginning of the whole input
+
+@item @samp{\'} matches the end of the whole input
+
+@end enumerate
+
+
+Grouping is performed with parentheses @samp{()}. An unmatched @samp{)} matches just itself. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{(}.
+
+The alternation operator is @samp{|}.
+
+The characters @samp{^} and @samp{$} always represent the beginning and end of a string respectively, except within square brackets. Within brackets, @samp{^} can be used to invert the membership of the character class being specified.
+
+@samp{*}, @samp{+} and @samp{?} are special at any point in a regular expression except the following places, where they are illegal:
+@enumerate
+
+@item At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{(}
+@item After the alternation operator @samp{|}
+
+@end enumerate
+
+
+Intervals are specified by @samp{@{} and @samp{@}}. Invalid intervals such as @samp{a@{1z} are not accepted.
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node posix-minimal-basic regular expression syntax
+@subsection @samp{posix-minimal-basic} regular expression syntax
+
+
+The character @samp{.} matches any single character except the null character.
+
+
+
+Bracket expressions are used to match ranges of characters. Bracket expressions where the range is backward, for example @samp{[z-a]}, are invalid. Within square brackets, @samp{\} is taken literally. Character classes are supported; for example @samp{[[:digit:]]} will match a single decimal digit.
+
+GNU extensions are supported:
+@enumerate
+
+@item @samp{\w} matches a character within a word
+
+@item @samp{\W} matches a character which is not within a word
+
+@item @samp{\<} matches the beginning of a word
+
+@item @samp{\>} matches the end of a word
+
+@item @samp{\b} matches a word boundary
+
+@item @samp{\B} matches characters which are not a word boundary
+
+@item @samp{\`} matches the beginning of the whole input
+
+@item @samp{\'} matches the end of the whole input
+
+@end enumerate
+
+
+Grouping is performed with backslashes followed by parentheses @samp{\(}, @samp{\)}. A backslash followed by a digit acts as a back-reference and matches the same thing as the previous grouped expression indicated by that number. For example @samp{\2} matches the second group expression. The order of group expressions is determined by the position of their opening parenthesis @samp{\(}.
+
+
+
+The character @samp{^} only represents the beginning of a string when it appears:
+@enumerate
+
+@item
+At the beginning of a regular expression
+
+@item After an open-group, signified by
+@samp{\(}
+
+@end enumerate
+
+
+The character @samp{$} only represents the end of a string when it appears:
+@enumerate
+
+@item At the end of a regular expression
+
+@item Before an close-group, signified by
+@samp{\)}
+@end enumerate
+
+
+
+
+Intervals are specified by @samp{\@{} and @samp{\@}}. Invalid intervals such as @samp{a\@{1z} are not accepted.
+
+The longest possible match is returned; this applies to the regular expression as a whole and (subject to this constraint) to subexpressions within groups.
+
+
+@node sed regular expression syntax
+@subsection @samp{sed} regular expression syntax
+This is a synonym for ed.
\ No newline at end of file
projects / gnulib.git / blobdiff