WORDEXP(3)                 Linux Programmer's Manual                WORDEXP(3)

       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);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       wordexp(), wordfree(): _XOPEN_SOURCE

       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.

   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 unescaped 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 (re-
       placing $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  argument  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 requested, but the WRDE_NOCMD flag told us
              to consider this an error.

              Out of memory.

              Shell syntax error, such as unbalanced parentheses or  unmatched

       wordexp() and wordfree() are provided in glibc since version 2.1.

       For  an  explanation  of  the  terms  used  in  this  section,  see at-

       |Interface  | Attribute     | Value                          |
       |wordexp()  | Thread safety | MT-Unsafe race:utent const:env |
       |           |               | env sig:ALRM timer locale      |
       |wordfree() | Thread safety | MT-Safe                        |
       In the above table, utent in race:utent signifies that if  any  of  the
       functions setutent(3), getutent(3), or endutent(3) are used in parallel
       in different threads of a program, then data races could occur.   word-
       exp() calls those functions, so we use race:utent to remind users.

       POSIX.1-2001, POSIX.1-2008.

       The  output  of  the following example program is approximately that of
       "ls [a-c]*.c".

       #include <stdio.h>
       #include <stdlib.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]);

       fnmatch(3), glob(3)

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                                  2017-09-15                        WORDEXP(3)
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