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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).

       ┌───────────┬───────────────┬────────────────────────────────┐
       │InterfaceAttributeValue                          │
       ├───────────┼───────────────┼────────────────────────────────┤
       │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.

EXAMPLE

       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;
           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]);
           wordfree(&p);
           exit(EXIT_SUCCESS);
       }

SEE ALSO

       fnmatch(3), glob(3)

COLOPHON

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

                                            2017-09-15                                 WORDEXP(3)