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        wordexp, wordfree - perform word expansion like a posix-shell


        #include <wordexp.h>
        int wordexp(const char *s, wordexp_t *p, int flags);
        void wordfree(wordexp_t *p);


        The  function wordexp() performs a shell-like expansion of the string s
        and returns the result in the structure pointed to by p.  The data type
        wordexp_t  is  a  structure  that  at  least  has  the fields we_wordc,
        we_wordv, and we_offs.  The field we_wordc is a size_t that  gives  the
        number of words in the expansion of s.  The field we_wordv is a char **
        that points to the array of words found.  The  field  we_offs  of  type
        size_t  is  sometimes  (depending on flags, see below) used to indicate
        the number of initial elements in the we_wordv  array  that  should  be
        filled with NULLs.
        The  function  wordfree()  frees the allocated memory again.  More pre‐
        cisely, it does not free its argument, but it frees the array  we_wordv
        and the strings that points to.
        First  a  small  example.   The output is approximately that of "ls [a-
        #include <stdio.h>
        #include <wordexp.h>
        main(int argc, char **argv)
            wordexp_t p;
            char **w;
            int i;
            wordexp("[a-c]*.c", &p, 0);
            w = p.we_wordv;
            for (i=0; i<p.we_wordc; i++)
                printf("%s\n", w[i]);
    The string argument
        Since the expansion is the same as the  expansion  by  the  shell  (see
        sh(1))  of  the  parameters to a command, the string s must not contain
        characters that would be illegal in shell command parameters.  In  par‐
        ticular, there must not be any non-escaped newline or |, &, ;, <, >, (,
        ), {, } characters outside a command substitution or parameter  substi‐
        tution context.
        If  the argument s contains a word that starts with an unquoted comment
        character #, then it is unspecified whether that word and all following
        words are ignored, or the # is treated as a non-comment character.
    The expansion
        The  expansion  done  consists of the following stages: tilde expansion
        (replacing ~user  by  user’s  home  directory),  variable  substitution
        (replacing  $FOO by the value of the environment variable FOO), command
        substitution (replacing $(command) or ‘command‘ by the output  of  com‐
        mand), arithmetic expansion, field splitting, wildcard expansion, quote
        The result of expansion of special parameters ($@, $*, $#, $?, $-,  $$,
        $!, $0) is unspecified.
        Field  splitting is done using the environment variable $IFS.  If it is
        not set, the field separators are space, tab and newline.
    The output array
        The array we_wordv contains the words found, followed by a NULL.
    The flags argument
        The flag argument is a bitwise inclusive OR of the following values:
               Append the words found to the array resulting  from  a  previous
               Insert  we_offs initial NULLs in the array we_wordv.  (These are
               not counted in the returned we_wordc.)
               Don’t do command substitution.
               The parameter p resulted from a previous call to wordexp(),  and
               wordfree() was not called.  Reuse the allocated storage.
               Normally  during  command  substitution  stderr is redirected to
               /dev/null.  This flag specifies that stderr is not to  be  redi‐
               Consider it an error if an undefined shell variable is expanded.
        In case of success 0 is returned.  In case of error one of the  follow‐
        ing five values is returned.
               Illegal  occurrence of newline or one of |, &, ;, <, >, (, ), {,
               An undefined shell variable was referenced, and  the  WRDE_UNDEF
               flag told us to consider this an error.
               Command  substitution  occurred, and the WRDE_NOCMD flag told us
               to consider this an error.
               Out of memory.
               Shell syntax error, such as unbalanced parentheses or  unmatched
        fnmatch(3), glob(3)
                                   2003-11-11                        WORDEXP(3)