BPX1ITY (isatty) example

The following code determines if the standard output device is a terminal. For the callable service, see isatty (BPX1ITY) (POSIX Version) — Determine whether a file descriptor represents a terminal.

                                              
         CALL  BPX1ITY,              Determine if device is a TTY      +
               (=A(STDOUT_FILENO),   Input: File descriptor            +
               RETVAL),              Return value: 0 isn't, 1 is       +
               VL,MF=(E,PLIST)       ---------------------------------- 
         ICM   R15,B'1111',RETVAL    Test RETVAL                        
         BZ    PSEUDO                RETVAL=0 means device not terminal