MTB 743-00 Multics Technical Bulletin
To: MTB Distribution
From: Ed Brunelle
Al Dupuis
Ron Barstad
Ed Wallman
Date: 04/09/86
Subject: MOWSE - Personal Computer File Backup (PCFB) Facility
ABSTRACT
This MTB describes a file backup and restore facility for a
Personal Computer (PC) using a Multics system as the file storage
medium. This facility uses the Multics Online Work Station
Environment (MOWSE). There are five MTBs that describe the
design and implementation of MOWSE and some applications that use
MOWSE facilities. The five MTBs are:
MTB-740 MOWSE Overview
MTB-741 MOWSE Design, Commands and Subroutines
MTB-742 MOWSE Background File Transfer (BFT) Facility
MTB-743 MOWSE Personal Computer File Backup (PCFB) Facility
MTB-744 MOWSE Terminal Emulator
Comments may be made:
Via forum:
>udd>m>jms>mtgs>workstation_working_group (wwg) on System-M
_________________________________________________________________
Multics Project internal working documentation. Not to be
reproduced outside the Multics Project.
MTB 743-00 Multics Technical Bulletin
INTRODUCTION
------------
With the proliferation of personal computers (PCs) being used as
remote terminals to Multics, a need has arisen to allow the PC
user to utilize the Multics system as a backup system for their
files.
This MTB discusses a minimal system that can be used to move
copies of files from the personal computer to Multics for backup
purposes, and to move copies of the files from Multics back to
the personal computer for recovery purposes. A minimal system is
proposed because only a small amount of resources are to be spent
designing and coding this system.
FUNCTIONAL DESCRIPTION
----------------------
The proposed system will be able to:
o transfer files from a personal computer to Multics, and from
Multics to a personal computer
o handle individual files, complete directories, and complete
directories with their subtrees
o accept starnames for the specification of the source files to
transfer, and starnames for the source files to exclude from
the transfer
o provide a way for a user to cancel a dump or a retrieval
request
o provide a way for a user to restart a dump or retrieval after a
system interruption
PROPOSED OPERATION
------------------
PCFB will use a replacement-only algorithm for transfer of files
in both directions. By replacement-only we mean that files which
already exist will be ovewritten. Files transferred from the
personal computer to Multics will be placed under the PCFB
directory ([hd]>Person.mowse>pcfb). If a file "foo" is
transferred from "a:bcd" on the personal computer, the
directories b, c, and d will be created below the PCFB directory
and foo will be placed there. Transfers from Multics to the
personal computer will work the same way.
A person who uses PCFB will be responsible for managing the
backed up files and directories. There are several problems with
MTB 743-00 Multics Technical Bulletin
the replacement-only algorithm, but hopefully users can solve
most of them procedurely. After a determination has been made
regarding the best procedures, these can be recommended in the
PCFB documentation.
An initial guess is that a user should create a directory on the
personal computer where she puts files that need to be backed up.
After they arrive on Multics she could rename them to some
date-based convention that would allow her to keep multiple
versions.
PCFB will only allow one dump or retrieval to be in progress at
one time.
USER INTERFACE
--------------
The functions described here will be provided through an ssu_
subsystem. The command will be called pc_file_backup (pcfb) and
will provide the usual subsystem-type control arguments. Within
the subsystem the abort_dump, abort_retrieve, begin_dump,
begin_retrieve, restart_dump, restart_retrieve, and status
requests will be provided.
The remainder of this MTB is the command and request
descriptions.
MTB 743-00 Multics Technical Bulletin
Command Description
Name: pc_file_backup (pcfb)
Syntax: pc_file_backup {-control_args}
Function: The pc_file_backup (pcfb) command enters an
interactive subsystem which provides a method to backup files
from a personal computer to Multics, and to restore files from
Multics to the personal computer. Once the command is invoked,
you are placed in the pcfb subsystem, where you must use pcfb
requests. pcfb requests are listed below.
Control Arguments:
-abbrev, -ab
specifies that abbreviation processing should be done. If
the -profile argument is not given, the user's default
profile segment (>udd>Project_id>Person_id>Person_id.profile)
is used.
-no_abbrev, -nab
specifies that abbreviation processing is not to be done.
(Default)
-no_quit
tells pc_file_backup to enter a request loop where request
lines are read by the pc_file_backup request processor.
(Default)
-no_start_up, -nsu
does not execute the start_up exec_com.
-profile pathname, -pf pathname
specifies that abbreviation processing is to be done using
the profile named profile_path. If this control argument is
given, the -abbrev argument need not be given.
-quit
tells pc_file_backup to process the initial request line and
then return without entering the request loop (even if the
initial request line is aborted).
-request string, -rq string
executes the requests in string before entering the request
loop.
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-start_up, -su
executes the start_up exec_com. (Default)
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List Of Requests
__________ __________
abort_dump abort_dump
__________ __________
Name: abort_dump (ad)
Syntax: abort_dump {-control_args}
Function: aborts the dump that is currently in progress.
Control Arguments:
-force, -fc
specifies that the dump should be aborted without issuing a
query.
-no_force, -nfc
specifies that a query should be issued that will insure the
user wants the dump to be aborted. (Default)
MTB 743-00 Multics Technical Bulletin
______________ ______________
abort_retrieve abort_retrieve
______________ ______________
Name: abort_retrieve (ar)
Syntax: abort_retrieve {-control_args}
Function: aborts the retrieve that is currently in progress.
Control Arguments:
-force, -fc
specifies that the retrieve should be aborted without issuing
a query.
-no_force, -nfc
specifies that a query should be issued that will insure the
user wants the retrieve to be aborted. (Default)
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__________ __________
begin_dump begin_dump
__________ __________
Name: begin_dump (bd)
Syntax: begin_dump -control_args
Function: begins a dump of files from a personal computer to
Multics.
Control Arguments:
-notify, -nt
specifies that pcfb should print a message when the operation
has completed.
-no_notify, -nnt
specifies that pcfb should not print a message when the
operation has completed. (Default)
-pathname PATHNAME_SET {...-pn PATHNAME_SET}
where PATHNAME_SET specifies the files and/or directories
that will be dumped from the personal computer to Multics.
The syntax for PATHNAME_SET is:
PATH1 {-subtree | -no_subtree}
{-exclude PATH2 {...PATHn}}
where:
PATH1
is an MS-DOS pathname that is used to identify the files
and directories that are to be dumped. (See "Notes"
below.)
-exclude PATH2 {...PATHn}, -ex PATH2 {...PATHn}
are files or directories that are to be excluded from the
dump. (See "Notes" below.)
-no_subtree, -nsubt
specifies that the subtree below the directory identified
by PATH1 should not be dumped. (Default)
-subtree, -subt
specifies that the subtree below the directory identified
by PATH1 is to be dumped also. If PATH1 identifies a
file instead of a directory, this control argument is
ignored.
MTB 743-00 Multics Technical Bulletin
Notes:
The PATHNAME_SET can be given more than once on a request line.
PATH can be an absolute or relative MS-DOS pathname. When
multiple PATH's are given with the -exclude argument, they must
all be relative or absolute (mixing absolute and relative
pathnames isn't supported). The entryname portion of PATH can be
the name of a directory or a file. The entryname portion can
also be an MS-DOS STARNAME, which is used to match against files
only (not directories).
MTB 743-00 Multics Technical Bulletin
______________ ______________
begin_retrieve begin_retrieve
______________ ______________
Name: begin_retrieve (br)
Syntax: begin_retrieve -control_args
Function: begins a retrieval of files from Multics to a personal
computer.
Control Arguments:
-notify, -nt
specifies that pcfb should print a message when the operation
has completed.
-no_notify, -nnt
specifies that pcfb should not print a message when the
operation has completed. (Default)
-pathname PATHNAME_SET {...-pn PATHNAME_SET}
where PATHNAME_SET specifies the files and/or directories
that will be restored from Multics to the personal computer.
See the begin_dump request description for the syntax for
PATHNAME_SET.
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____________ ____________
restart_dump restart_dump
____________ ____________
Name: restart_dump (rd)
Syntax: restart_dump
Function: restarts the dump that was interrupted.
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________________ ________________
restart_retrieve restart_retrieve
________________ ________________
Name: restart_retrieve (rr)
Syntax: restart_retrieve
Function: restarts the retrieve that was interrupted.
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______ ______
status status
______ ______
Name: status (st)
Syntax: status
Function: prints status information about the dump or retrieval
that is in progress.