*Conan The Librarian
1.$ EXIT 1 The EXIT command in this example exits to the next higher command level, giving $STATUS and $SEVERITY a value of 1. 2.$ ON WARNING THEN EXIT $ FORTRAN 'P1' $ LINK 'P1' $ RUN 'P1' The EXIT command in this example is used as the target of an ON command; this statement ensures that the command procedure terminates whenever any warnings or errors are issued by any command in the procedure. The procedure exits with the status value of the command or program that caused the termination. 3.$ START: $ IF (P1 .EQS. "TAPE") .OR. (P1 .EQS. "DISK") THEN GOTO 'P1' $ INQUIRE P1 "Enter device (TAPE or DISK)" $ GOTO START $ TAPE: ! Process tape files . . . $ EXIT $ DISK: ! Process disk files . . . $ EXIT The command procedure in this example shows how to use the EXIT command to terminate different command paths within the procedure. To execute the procedure, you must enter either TAPE or DISK as a parameter. The IF command uses a logical OR to test whether either of these strings was entered. If the result is true, the GOTO command branches to the corresponding label. If P1 was neither TAPE nor DISK, the INQUIRE command prompts for a correct parameter. The commands following each of the labels TAPE and DISK provide different paths through the procedure. The EXIT command before the label DISK ensures that the commands after the label DISK are executed only if the procedure explicitly branches to DISK. Note that the EXIT command at the end of the procedure is not required because the end of the procedure causes an implicit EXIT command. Use of the EXIT command, however, is recommended. 4.$ IF P1. EQS. "" THEN - INQUIRE P1 "Enter filespec (null to exit)" $ IF P1 .EQS. "" THEN EXIT $ PRINT 'P1'/AFTER=20:00/COPIES=50/FORMS=6 The command procedure in this example tests whether a parameter was passed to it; if the parameter was not passed, the procedure prompts for the required parameter. Then it retests the parameter P1. If a null string, indicated by a carriage return for a line with no data, is entered, the procedure exits; otherwise, it executes the PRINT command with the current value of P1 as the input parameter. 5.$ IF P1 .EQS. "" THEN INQUIRE P1 "Code" $ CODE = %X'P1' $ EXIT CODE The command procedure in this example, E.COM, illustrates how to determine the system message, if any, associated with a hexadecimal system status code. The procedure requires a parameter and prompts if none is entered. Then it prefixes the value with the radix operator %X and assigns this string to the symbol CODE. Finally, it issues the EXIT command with the hexadecimal value. The following example uses the procedure E.COM: $ @E 1C %SYSTEM-F-EXQUOTA, exceeded quota When the procedure exits, the value of $STATUS is %X1C, which equates to the EXQUOTA message. Note that you can also use the F$MESSAGE lexical function to determine the message that corresponds to a status code. 6.$ RUN MYPROG <Ctrl/Y> $ EXIT In this interactive example, the RUN command initiates execution of the image MYPROG.EXE. Then pressing Ctrl/Y interrupts the execution. The EXIT command that follows calls any exit handlers declared by the image before terminating MYPROG.EXE.