Returns a message indicating why an ONC RPC routine failed.
    Format
      #include  <rpc/rpc.h>
      char  *clnt_sperror(CLIENT *handle, char *sp);

1  –  Arguments

 handle
    A pointer to the client handle used in the call that failed.
 sp
    A pointer to a string to be used as the beginning of the error
    message.

2  –  Description

    The clnt_sperror routine returns a pointer to a message string.
    The message consists of the sp parameter followed by an error
    message generated by calling the clnt_sperrno routine. Use this
    routine when the clnt_call routine fails.

    Use this routine if:
    o  You want to save the string.
    o  You do not want to use fprintf to print the message.
    o  The message format is different from the one that clnt_perrno
       supports.

    The address that clnt_sperror returns is a pointer to its own
    internal string buffer. The clnt_sperror routine overwrites this
    buffer with each call. Therefore, you must copy the string to
    your own buffer if you wish to save the string.

3  –  Return Values

    char *             A pointer to the message string terminated
                       with a NULL character.
    NULL               The routine was not able to allocate its
                       internal buffer.