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

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

SYNOPSIS
       #include <wordexp.h>

       int wordexp(const char *restrict s, wordexp_t *restrict p, int flags);
       void wordfree(wordexp_t *p);

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

       wordexp(), wordfree():
           _XOPEN_SOURCE

DESCRIPTION
       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 precisely, 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 particular, there must not be any unescaped newline or |, &, ;, <, >, (, ), {, } characters outside a command  substitu‐
       tion or parameter substitution 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 command), arithmetic expansion, field splitting,
       wildcard expansion, quote removal.

       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:

       WRDE_APPEND
              Append the words found to the array resulting from a previous call.

       WRDE_DOOFFS
              Insert we_offs initial NULLs in the array we_wordv.  (These are not counted in the returned we_wordc.)

       WRDE_NOCMD
              Don't do command substitution.

       WRDE_REUSE
              The argument p resulted from a previous call to wordexp(), and wordfree() was not called.  Reuse the allocated storage.

       WRDE_SHOWERR
              Normally during command substitution stderr is redirected to /dev/null.  This flag specifies that stderr is not to be redirected.

       WRDE_UNDEF
              Consider it an error if an undefined shell variable is expanded.

RETURN VALUE
       On success, wordexp() returns 0.  On failure, wordexp() returns one of the following nonzero values:

       WRDE_BADCHAR
              Illegal occurrence of newline or one of |, &, ;, <, >, (, ), {, }.

       WRDE_BADVAL
              An undefined shell variable was referenced, and the WRDE_UNDEF flag told us to consider this an error.

       WRDE_CMDSUB
              Command substitution requested, but the WRDE_NOCMD flag told us to consider this an error.

       WRDE_NOSPACE
              Out of memory.

       WRDE_SYNTAX
              Shell syntax error, such as unbalanced parentheses or unmatched quotes.

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

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
       β”‚Interface  β”‚ Attribute     β”‚ Value                                                                                                                              β”‚
       β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
       β”‚wordexp()  β”‚ Thread safety β”‚ MT-Unsafe race:utent const:env env sig:ALRM timer locale                                                                           β”‚
       β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
       β”‚wordfree() β”‚ Thread safety β”‚ MT-Safe                                                                                                                            β”‚
       β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜
       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.  wordexp() calls those functions, so we use race:utent to remind users.

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008.

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

       #include <stdio.h>
       #include <stdlib.h>
       #include <wordexp.h>

       int
       main(int argc, char *argv[])
       {
           wordexp_t p;
           char **w;

           wordexp("[a-c]*.c", &p, 0);
           w = p.we_wordv;
           for (int i = 0; i < p.we_wordc; i++)
               printf("%s\n", w[i]);
           wordfree(&p);
           exit(EXIT_SUCCESS);
       }

SEE ALSO
       fnmatch(3), glob(3)

                                                                               2021-08-27                                                                     WORDEXP(3)