NAME

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

SYNOPSIS

       #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

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 substitution 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

       In case of success 0 is returned.  In case of error one of the following five values is returned.

       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).

       ┌───────────┬───────────────┬────────────────────────────────┐
       │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.
       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)

COLOPHON

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       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       https://www.kernel.org/doc/man-pages/.

                                                   2020-11-01                                         WORDEXP(3)