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 execle()                Execute Child Process Using Arg List and
Environment

 #include   <process.h>

 int        execle(pathname, arg0,arg1,...,argn,NULL,envp);
 char       *pathname;                   Path name of file to be executed
 char       *arg0,*arg1,...,*argn;       List of pointers to arguments
 char       *envp[];                     Array of pointers to environment

    execle() loads and executes a new child process.  Arguments are
    passed to the child process as a list of pointers, arg0 to argn.  The
    child process is placed in the memory currently occupied by the
    calling process. There must be enough available memory to load and
    execute the child process.

    'pathname' specifies the file name of the child process.  If
    'pathname' has a file name extension, then only that file is searched
    for. If 'pathname' ends with a period (.), then 'pathname' without an
    extension is searched for.  If 'pathname' has no extension and does
    not end with a period, then execle() searches for 'pathname' and, if
    it is not found, appends ".COM" and searches again. If that is not
    found, it appends ".EXE" and searches again.

     'arg0', 'arg1',...'argn' are passed to the child process as command-
    line parameters.  'argn' must be followed by a NULL pointer, which
    terminates the list of arguments. 'arg0' must not be NULL, and is
    usually set to 'pathname'.

    The maximum length for all strings forming the argument list passed
    to the child process is 128 bytes.  This includes "n" (for 0 to n
    arguments) space characters (required to separate the arguments), but
    does not include the null ('\0') terminating character.

    'envp' points to an array of pointers that in turn point to strings
    that define environment variables.  These strings usually have the
    form:  ENVVAR=value where "ENVVAR" is the name of the environment
    variable and "value" is the string value to set it to.  The 'envp'
    array is terminated by a NULL pointer.  If 'envp' is NULL, then the
    child process acquires the environment of the calling process.

    Returns:    If execle() is successful, it does not return to the
                calling process. (See the spawn...() routines for a
                similar function that can return to the calling process).
                If an error occurs, execle() returns -1 to the calling
                process. On error, 'errno' (defined in <stdlib.h>) is set
                to one of the following values (defined in <errno.h>):

                    E2BIG       Argument list or environment list too big.
                                (List > 128 bytes, or environment > 32k)
                    EACCES      Locking or sharing violation on file.
                                   (MS-DOS 3.0 and later)
                    EMFILE      Too many files open.
                    ENOENT      File or path not found.
                    ENOEXEC     File not executable.
                    ENOMEM      Not enough memory.

      Notes:    Any file open when an exec call is made remains open in
                the child process.  This includes 'stdin','stdout',
                'stderr', 'stdaux', and 'stdprn'.

                The translation modes of open files are not preserved by
                execle().  Use setmode() in the child process to set the
                desired translation modes.

                'environ' (defined in <stdlib.h>) points to a list of
                environment settings for the current process.

                See the spawn...() routines for similar though more
                flexible functions that can return to the calling
                program.

    Caution:    The file pointers to open buffered files are not always
                preserved correctly.  The information in the buffer may
                be lost.

                Signal settings are not preserved.  They are reset to the
                default in the child process.

 Portability:   Xenix, OS/2, or MS-DOS 3.0 or higher.

   ----------------------------- Example -------------------------------

    The following statements transfer execution to the child process
    "child.exe" and pass it the three arguments "child", "arg1", and
    "arg2".  The PATH environment variable is set to "C:\TEST":

           #include <process.h>    /* for 'execle' */
           #include <stdio.h>      /* for 'printf' and 'NULL' */
           #include <stdlib.h>     /* for 'errno' */
           #include <errno.h>      /* for 'ENOENT' and 'ENOMEM' */

           char *env[] = {"PATH=C:\\TEST", NULL};

           main()
           {
               execle("child.exe", "child", "arg1", "arg2", NULL, env);
               /* only get here on an exec error */
               if (errno == ENOENT)
                   printf("child.exe not found in current directory\n");
               else if (errno == ENOMEM)
                   printf("not enough memory to execute child.exe\n");
               else
                   printf("error #%d trying to exec child.exe\n", errno);
           }