wordexp Example

Here is an example of using wordexp to expand several strings and use the results to run a shell command. It also shows the use of WRDE_APPEND to concatenate the expansions and of wordfree to free the space allocated by wordexp.

int
expand_and_execute (const char *program, const char *options)
{
  wordexp_t result;
  pid_t pid
  int status, i;

  /* Expand the string for the program to run.  */
  switch (wordexp (program, &result, 0))
    {
    case 0:			/* Successful.  */
      break;
    case WRDE_NOSPACE:
      /* If the error was WRDE_NOSPACE,
         then perhaps part of the result was allocated.  */
      wordfree (&result);
    default:                    /* Some other error.  */
      return -1;
    }

  /* Expand the strings specified for the arguments.  */
  for (i = 0; args[i]; i++)
    {
      if (wordexp (options, &result, WRDE_APPEND))
        {
          wordfree (&result);
          return -1;
        }
    }

  pid = fork ();
  if (pid == 0)
    {
      /* This is the child process.  Execute the command. */
      execv (result.we_wordv[0], result.we_wordv);
      exit (EXIT_FAILURE);
    }
  else if (pid < 0)
    /* The fork failed.  Report failure.  */
    status = -1;
  else
    /* This is the parent process.  Wait for the child to complete.  */
    if (waitpid (pid, &status, 0) != pid)
      status = -1;

  wordfree (&result);
  return status;
}

In practice, since wordexp is executed by running a subshell, it would be faster to do this by concatenating the strings with spaces between them and running that as a shell command using `sh -c'.

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