-To free any allocated fields of a pattern buffer, you can use the
-@sc{posix} function described in @ref{Freeing POSIX Pattern Buffers},
-since the type @code{regex_t}---the type for @sc{posix} pattern
-buffers---is equivalent to the type @code{re_pattern_buffer}. After
-freeing a pattern buffer, you need to again compile a regular expression
-in it (@pxref{GNU Regular Expression Compiling}) before passing it to
-a matching or searching function.
-
-
-@node POSIX Regex Functions
-@section POSIX Regex Functions
-
-If you're writing code that has to be @sc{posix} compatible, you'll need
-to use these functions. Their interfaces are as specified by @sc{posix},
-draft 1003.2/D11.2.
-
-@menu
-* POSIX Pattern Buffers:: The regex_t type.
-* POSIX Regular Expression Compiling:: regcomp ()
-* POSIX Matching:: regexec ()
-* Reporting Errors:: regerror ()
-* Using Byte Offsets:: The regmatch_t type.
-* Freeing POSIX Pattern Buffers:: regfree ()
-@end menu
-
-
-@node POSIX Pattern Buffers
-@subsection POSIX Pattern Buffers
-
-To compile or match a given regular expression the @sc{posix} way, you
-must supply a pattern buffer exactly the way you do for @sc{gnu}
-(@pxref{GNU Pattern Buffers}). @sc{posix} pattern buffers have type
-@code{regex_t}, which is equivalent to the @sc{gnu} pattern buffer
-type @code{re_pattern_buffer}.
-
-
-@node POSIX Regular Expression Compiling
-@subsection POSIX Regular Expression Compiling
-
-With @sc{posix}, you can only search for a given regular expression; you
-can't match it. To do this, you must first compile it in a
-pattern buffer, using @code{regcomp}.
-
-@ignore
-Before calling @code{regcomp}, you must initialize this pattern buffer
-as you do for @sc{gnu} (@pxref{GNU Regular Expression Compiling}). See
-below, however, for how to choose a syntax with which to compile.
-@end ignore
-
-To compile a pattern buffer, use:
-
-@findex regcomp
-@example
-int
-regcomp (regex_t *@var{preg}, const char *@var{regex}, int @var{cflags})
-@end example
-
-@noindent
-@var{preg} is the initialized pattern buffer's address, @var{regex} is
-the regular expression's address, and @var{cflags} is the compilation
-flags, which Regex considers as a collection of bits. Here are the
-valid bits, as defined in @file{regex.h}:
-
-@table @code
-
-@item REG_EXTENDED
-@vindex REG_EXTENDED
-says to use @sc{posix} Extended Regular Expression syntax; if this isn't
-set, then says to use @sc{posix} Basic Regular Expression syntax.
-@code{regcomp} sets @var{preg}'s @code{syntax} field accordingly.
-
-@item REG_ICASE
-@vindex REG_ICASE
-@cindex ignoring case
-says to ignore case; @code{regcomp} sets @var{preg}'s @code{translate}
-field to a translate table which ignores case, replacing anything you've
-put there before.
-
-@item REG_NOSUB
-@vindex REG_NOSUB
-says to set @var{preg}'s @code{no_sub} field; @pxref{POSIX Matching},
-for what this means.
-
-@item REG_NEWLINE
-@vindex REG_NEWLINE
-says that a:
-
-@itemize @bullet
-
-@item
-match-any-character operator (@pxref{Match-any-character
-Operator}) doesn't match a newline.
-
-@item
-nonmatching list not containing a newline (@pxref{List
-Operators}) matches a newline.
-
-@item
-match-beginning-of-line operator (@pxref{Match-beginning-of-line
-Operator}) matches the empty string immediately after a newline,
-regardless of how @code{REG_NOTBOL} is set (@pxref{POSIX Matching}, for
-an explanation of @code{REG_NOTBOL}).
-
-@item
-match-end-of-line operator (@pxref{Match-beginning-of-line
-Operator}) matches the empty string immediately before a newline,
-regardless of how @code{REG_NOTEOL} is set (@pxref{POSIX Matching},
-for an explanation of @code{REG_NOTEOL}).
-
-@end itemize
-
-@end table
-
-If @code{regcomp} successfully compiles the regular expression, it
-returns zero and sets @code{*@var{pattern_buffer}} to the compiled
-pattern. Except for @code{syntax} (which it sets as explained above), it
-also sets the same fields the same way as does the @sc{gnu} compiling
-function (@pxref{GNU Regular Expression Compiling}).
-
-If @code{regcomp} can't compile the regular expression, it returns one
-of the error codes listed here. (Except when noted differently, the
-syntax of in all examples below is basic regular expression syntax.)
-
-@table @code
-
-@comment repetitions
-@item REG_BADRPT
-For example, the consecutive repetition operators @samp{**} in
-@samp{a**} are invalid. As another example, if the syntax is extended
-regular expression syntax, then the repetition operator @samp{*} with
-nothing on which to operate in @samp{*} is invalid.
-
-@item REG_BADBR
-For example, the @var{count} @samp{-1} in @samp{a\@{-1} is invalid.
-
-@item REG_EBRACE
-For example, @samp{a\@{1} is missing a close-interval operator.
-
-@comment lists
-@item REG_EBRACK
-For example, @samp{[a} is missing a close-list operator.
-
-@item REG_ERANGE
-For example, the range ending point @samp{z} that collates lower than
-does its starting point @samp{a} in @samp{[z-a]} is invalid. Also, the
-range with the character class @samp{[:alpha:]} as its starting point in
-@samp{[[:alpha:]-|]}.
-
-@item REG_ECTYPE
-For example, the character class name @samp{foo} in @samp{[[:foo:]} is
-invalid.
-
-@comment groups
-@item REG_EPAREN
-For example, @samp{a\)} is missing an open-group operator and @samp{\(a}
-is missing a close-group operator.
-
-@item REG_ESUBREG
-For example, the back reference @samp{\2} that refers to a nonexistent
-subexpression in @samp{\(a\)\2} is invalid.
-
-@comment unfinished business
-
-@item REG_EEND
-Returned when a regular expression causes no other more specific error.
-
-@item REG_EESCAPE
-For example, the trailing backslash @samp{\} in @samp{a\} is invalid, as is the
-one in @samp{\}.
-
-@comment kitchen sink
-@item REG_BADPAT
-For example, in the extended regular expression syntax, the empty group
-@samp{()} in @samp{a()b} is invalid.
-
-@comment internal
-@item REG_ESIZE
-Returned when a regular expression needs a pattern buffer larger than
-65536 bytes.
-
-@item REG_ESPACE
-Returned when a regular expression makes Regex to run out of memory.
-
-@end table
-
-
-@node POSIX Matching
-@subsection POSIX Matching
-
-Matching the @sc{posix} way means trying to match a null-terminated
-string starting at its first character. Once you've compiled a pattern
-into a pattern buffer (@pxref{POSIX Regular Expression Compiling}), you
-can ask the matcher to match that pattern against a string using:
-
-@findex regexec
-@example
-int
-regexec (const regex_t *@var{preg}, const char *@var{string},
- size_t @var{nmatch}, regmatch_t @var{pmatch}[], int @var{eflags})
-@end example
-
-@noindent
-@var{preg} is the address of a pattern buffer for a compiled pattern.
-@var{string} is the string you want to match.
-
-@xref{Using Byte Offsets}, for an explanation of @var{pmatch}. If you
-pass zero for @var{nmatch} or you compiled @var{preg} with the
-compilation flag @code{REG_NOSUB} set, then @code{regexec} will ignore
-@var{pmatch}; otherwise, you must allocate it to have at least
-@var{nmatch} elements. @code{regexec} will record @var{nmatch} byte
-offsets in @var{pmatch}, and set to @math{-1} any unused elements up to
-@math{@var{pmatch}@code{[@var{nmatch}]} - 1}.
-
-@var{eflags} specifies @dfn{execution flags}---namely, the two bits
-@code{REG_NOTBOL} and @code{REG_NOTEOL} (defined in @file{regex.h}). If
-you set @code{REG_NOTBOL}, then the match-beginning-of-line operator
-(@pxref{Match-beginning-of-line Operator}) always fails to match.
-This lets you match against pieces of a line, as you would need to if,
-say, searching for repeated instances of a given pattern in a line; it
-would work correctly for patterns both with and without
-match-beginning-of-line operators. @code{REG_NOTEOL} works analogously
-for the match-end-of-line operator (@pxref{Match-end-of-line
-Operator}); it exists for symmetry.
-
-@code{regexec} tries to find a match for @var{preg} in @var{string}
-according to the syntax in @var{preg}'s @code{syntax} field.
-(@xref{POSIX Regular Expression Compiling}, for how to set it.) The
-function returns zero if the compiled pattern matches @var{string} and
-@code{REG_NOMATCH} (defined in @file{regex.h}) if it doesn't.
-
-@node Reporting Errors
-@subsection Reporting Errors
-
-If either @code{regcomp} or @code{regexec} fail, they return a nonzero
-error code, the possibilities for which are defined in @file{regex.h}.
-@xref{POSIX Regular Expression Compiling}, and @ref{POSIX Matching}, for
-what these codes mean. To get an error string corresponding to these
-codes, you can use:
-
-@findex regerror
-@example
-size_t
-regerror (int @var{errcode},
- const regex_t *@var{preg},
- char *@var{errbuf},
- size_t @var{errbuf_size})
-@end example
-
-@noindent
-@var{errcode} is an error code, @var{preg} is the address of the pattern
-buffer which provoked the error, @var{errbuf} is the error buffer, and
-@var{errbuf_size} is @var{errbuf}'s size.
-
-@code{regerror} returns the size in bytes of the error string
-corresponding to @var{errcode} (including its terminating null). If
-@var{errbuf} and @var{errbuf_size} are nonzero, it also returns in
-@var{errbuf} the first @math{@var{errbuf_size} - 1} characters of the
-error string, followed by a null.
-@var{errbuf_size} must be a nonnegative number less than or equal to the
-size in bytes of @var{errbuf}.
-
-You can call @code{regerror} with a null @var{errbuf} and a zero
-@var{errbuf_size} to determine how large @var{errbuf} need be to
-accommodate @code{regerror}'s error string.
-
-@node Using Byte Offsets
-@subsection Using Byte Offsets
-
-In @sc{posix}, variables of type @code{regmatch_t} hold analogous
-information, but are not identical to, @sc{gnu}'s registers (@pxref{Using
-Registers}). To get information about registers in @sc{posix}, pass to
-@code{regexec} a nonzero @var{pmatch} of type @code{regmatch_t}, i.e.,
-the address of a structure of this type, defined in
-@file{regex.h}:
-
-@tindex regmatch_t
-@example
-typedef struct
-@{
- regoff_t rm_so;
- regoff_t rm_eo;
-@} regmatch_t;
-@end example
-
-When reading in @ref{Using Registers}, about how the matching function
-stores the information into the registers, substitute @var{pmatch} for
-@var{regs}, @code{@w{@var{pmatch}[@var{i}]->}rm_so} for
-@code{@w{@var{regs}->}start[@var{i}]} and
-@code{@w{@var{pmatch}[@var{i}]->}rm_eo} for
-@code{@w{@var{regs}->}end[@var{i}]}.
-
-@node Freeing POSIX Pattern Buffers
-@subsection Freeing POSIX Pattern Buffers
-
-To free any allocated fields of a pattern buffer, use: