***********
                             * .SQUASH *
                             ***********

                        COMPILE LEVEL COMMAND

                               SYNTAX:
     .SQ [ODEV:[_IDEV:][ USING DEV:][ UNTIL NNN][ SAVE N][ WAIT]]



         SQUASH IS  A  DECSYSTEM-8  COMPILE  LEVEL  COMMAND  WHICH
    REPLACES  THE  "/S"  OPTION OF PIP.  IT IS AN IMPROVEMENT OVER
    THE OLD PIP SQUISH IN THAT FILE INTEGRETY  IS  MAINTAINED  FOR
    CERTAIN  OPERATIONS,  AND  THERE  ARE  MORE REASONABLE OPTIONS
    AVAILABLE.  EACH DECSYSTEM-8  DEVICE  MAY  CARRY  A  PARAMETER
    BLOCK  WHICH INDICATES, AMONG OTHER THINGS, WHETHER THE DEVICE
    MAY BE SQUASHED TO, IS ZEROABLE, AND/OR  MAY  BE  SQUASHED  TO
    ITSELF.   A  DEVICE  WITHOUT  A  PARAMETER  BLOCK  MAY ONLY BE
    SQUASHED TO ITSELF USING THIS COMMAND.


    THE "USING" DEVICE

         FOR SELF  SQUASHES  OF  DEVICES  (ESPECIALLY  TAPES),  AN
    INTERMEDIATE  DEVICE  MAY  BE  SPECIFIED   TO   EXPEDITE   THE
    OPERATION,  I.E. SPEED IT UP.  THIS DEVICE IS SPECIFIED BY THE
    USING DEV: OPTION IN THE COMMAND SYNTAX.  IF  THIS  DEVICE  IS
    ZEROABLE,  (ASCERTAINED  IN  THE  PARAMETER  BLOCK),  THEN THE
    ENTIRE DEVICE  IS  USED  FOR  INTERMEDIATE  STORAGE  OF  FILES
    DURRING  THE SQUASH.  A DIRECTORY IS MAINTAINED ON THIS DEVICE
    TO   GIVE   A  DEGREE  OF  FILE  SECURITY  DURING  THE  SQUASH
    OPERATION.  I.E. IF AN I/O ERROR  OCCURRS  WHILE  WRITING  THE
    FILES  BACK  ON  THE DEVICE BEING SQUASHED, THE OPERATION WILL
    TERMINATE, WITH A GOOD COPY OF THE FILE ON THE USING DEVICE.

         IF THE USING  DEVICE  IS  NOT  ZEROABLE,  IS  THE  SYSTEM
    DEVICE,  OR  IF  IT  DOES NOT HAVE A PARAMETER BLOCK, THEN THE
    LARGEST EMPTY SEGMENT ON THE DEVICE IS  USED  AS  INTERMEDIATE
    STORAGE.   IN  THIS  CASE THE DIRECTORY OF THE USING DEVICE IS
    NOT CHANGED AND AN I/O ERROR CAN  RESULT  IN  LOSS  OF  FILES.
    THIS  FEATURE  CAN  BE  EXCLUDED  BY  A  CONDITIONAL  ASSEMBLY
    PARAMETER, SYSOK, IN THE SOURCE.

         THE USING DEVICE MAY BE SHORTER  THAN  THE  DEVICE  BEING
    SQUASHED,  IN  WHICH  CASE MULTIPLE PASSES WILL BE MADE ON THE
    DEVICE.  THE ONE RESTRICTION IS THAT THE AVAILABLE STORAGE  ON
    THE  USING  DEVICE  MUST  BE  AT LEAST AS LARGE AS THE LARGEST
    FILE TO BE SQUASHED.


    THE "UNTIL" OPTION

         THE UNTIL  OPTION  IN  THE  COMMAND  SYNTAX  IS  USED  TO









    TERMINATE  THE  SQUASH  OPERATION  WHEN  A SPECIFIED NUMBER OF
    CONTIGUOUS FREE BLOCKS  BECOME  AVAILABLE.   OF  COURSE,  THIS
    OPTION  IS  ONLY MEANINGFUL FOR A SELF SQUASH, WITH OR WITHOUT
    A USING DEVICE.


    WAIT

         THIS OPTION WILL CAUSE THE PROCESSING OF THE  COMMAND  TO
    BE  INTERRUPTED  AFTER  THE  SYSTEM DEVICE IS NO LONGER NEEDED
    FOR PROCESSING.  AFTER THE MESSAGE "WAITING...", THE USER  MAY
    REMOUNT  TAPES,  INCLUDING  THE  REMOVAL  OF  SYS.  TYPING ANY
    CHARACTER WILL CONTINUE PROCESSING  OF  THE  COMMAND.   BEFORE
    RETURNING  TO THE MONITOR, THE MESSAGE "WAITING..." WILL AGAIN
    BE TYPED TO ALLOW THE USER TO REMOUNT SYS, OR OTHER TAPES.


    THE "SAVE" OPTION

         THE SAVE OPTION ALLOWS SAVING EXTRA INFORMATION WORDS  IN
    THE  DIRECTORY OF THE DEVICE.  IF NO SAVE OPTION IS GIVEN THEN
    THE NUMBER OF  ADDITIONAL  INFORMATION  WORDS  IN  THE  INDEV:
    DIRECTORY  WILL  BE USED, UNLESS IT IS ZERO, IN WHICH CASE ONE
    ADDITIONAL INFORMATION WORD WILL BE RESERVED.


    FOR ALL OF THE ABOVE  OPTIONS,  ONLY  TWO  CHARACTERS  OF  THE
    OPTION NEED BE SPECIFIED.


    FILE INTEGRITY

         THERE  ARE  TWO  MODES OF TRANSFER IN THE SQUASH COMMAND:
    NORMAL   AND  SECURE.   THESE  COMMENTS  ONLY  APPLY  TO  SELF
    SQUASHES   WITH  NO  USING  DEVICE,  SINCE  ALL  OTHER  MODES,
    (EXCLUDING   THAT   MEANTIONED  UNDER  "USING"  DEVICES),  ARE
    NORMALLY SECURE.  DURRING A SECURE  SQUASH,  IF  A  FILE  WILL
    OVERWRITE  ITSELF  DURRING  THE TRANSFER, IT IS INSTEAD COPIED
    OUT ELSEWERE ON  THE  DEVICE  WITH  THE  OLD  DIRECTORY  ENTRY
    DELETED  ONLY IF THE TRANSFER IS SUSCESSFUL.  NORMAL SQUASHING
    CONTINUES FROM THAT POINT ONCE THE NEW  DIRECTORY  IS  WRITTEN
    OUT.   IF  THERE  IS  NO  EMPTY  LARGE ENOUGH TO COPY THE FILE
    INTO, THE OPERATOR IS  NOTIFIED  AND  ASKED  IF  HE  WANTS  TO
    TRANSFER  THE FILE IN THE NON-SECURE MODE.  IT SHOULD BE NOTED
    THAT THE ORDER  OF  FILES  MAY  CHANGE  WHEN  DOING  A  SECURE
    SQUASH.

         SINCE  THERE  IS  A  LOT  OF  TAPE  MOTION DURRING SECURE
    SQUASHES, THE SECURE MODE OF TRANSFER  WILL  ONLY  OCCUR  WHEN
    SQUASHING  DF32'S,  RF08'S,  AND  RK8'S.  CONDITIONAL ASSEMBLY
    PARAMETERS EXIST FOR ALWAYS DOING  SECURE  SQUASHES  OR  NEVER
    DOING  THEM  (THE  PARAMETERS VERYSAFE AND SQSAFELY).  ONLY IF
    I/O ERRORS OCCUR DURING WRITTING DIRECTORYS  SHOULD  FILES  BE
    LOST WHEN SQUASHING SECURELY.



                                 -1-







    CNTRL/C TERMINATION

         AT  ANY  TIME DURING A SQUASH OPERATION A ^C MAY BE TYPED
    TO TERMINATE THE SQUASH.  WHEN DETECTED, THE CURRENT  TRANSFER
    IS  COMPLETED,  AND  THE  REST  OF  THE DIRECTORY SYPONED DOWN
    CORRECTLY SO THAT NO FILES ARE LOST.
















































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