ARC

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                   ARC

                      File Archive Utility
                          Version 6.00

























                   COPYRIGHT 1985,86,87,88,89
                               by
               System Enhancement Associates, Inc.
                       ALL RIGHTS RESERVED





     This document describes version 6.00 of the ARC file
     utility, which was created by System Enhancement
     Associates, Inc. in January of 1989.


�       LIMITED WARRANTY


IMPORTANT NOTICE:
IMPORTANT NOTICE: Any use of this software for any
period of time for any purpose whatsoever constitutes
your unqualified acceptance of this LICENSE and
subjects you to all of the terms and conditions set
forth below:

System Enhancement Associates, Inc. ("SEA") warrants
to any Licensee that acquires the program from SEA or
an authorized SEA representative ONLY that:

 1) All diskettes SEA provides constitute an accurate
    duplication of the software and SEA will replace
    any diskette found to be defective within 30 days
    from date of acquisition.  SEA will not honor this
    warranty if the diskette has been subjected to
    physical abuse, or used in defective or non-
    compatible equipment.

 2) SEA's software will perform substantially as
    described in the documentation SEA regularly
    supplies with that software, if operated as
    prescribed in such documentation including the
    hardware and software environment specified.

 3) If a significant defect in any program is found,
    Licensee's only remedy shall be to receive refund
    of the actual fee Licensee paid for such defective
    program.  In no event will such a refund exceed
    the fee SEA charges for such program.

 4) SEA makes no warranty or representation that the
    software will be error free nor that its use by
    Licensee will be uninterrupted.

Except as provided above, SEA disclaims all other
warranties, either express or implied, including but
not limited to any implied warranty of merchantability
or fitness for any particular purpose.

Licensee agrees to take full responsibility for the
selection of and any use whatsoever made of the
software.

IN NO EVENT WILL SEA BE LIABLE FOR ANY DAMAGES
WHATSOEVER (INCLUDING WITHOUT LIMITATION DAMAGES FOR
LOSS OF BUSINESS PROFITS, BUSINESS INTERRUPTION, LOSS
OF BUSINESS INFORMATION OR THE LIKE) ARISING OUT OF
THE USE OF, INTERRUPTION IN THE USE OF, OR INABILITY
TO USE THIS SOFTWARE, EVEN IF SEA HAS BEEN ADVISED OF
ANY POSSIBILITY OR LIKELYHOOD OF SUCH DAMAGES.










�            TABLE OF CONTENTS


     _______                                           ____
     Section                                           Page

     Introduction  ....................................   1
     Using ARC  .......................................   3
     ARC commands  ....................................   5
         Adding files  ................................   5
         Extracting files  ............................   8
         Deleting files  ..............................   9
         Listing archive entries  .....................   9
         Running files  ...............................  12
         Printing files  ..............................  13
         Testing an archive  ..........................  13
         Converting an archive  .......................  14
     ARC options  .....................................  15
         Directories  .................................  15
         Level 5 compatibility  .......................  15
         Verbose mode  ................................  16
         Backup retention  ............................  16
         Suppressing compression  .....................  17
         Message suppression  .........................  18
         Encryption/Decryption  .......................  19
     Indirection  .....................................  21
     RAMdisk support  .................................  22
     Version numbers  .................................  23
     Common questions and answers  ....................  24
     Maintenance contracts  ...........................  26
     Revision history  ................................  27
         Changes in version 5  ........................  27
         Changes in version 5.3  ......................  29
         Changes in version 6.0  ......................  29
     Program history and credits  .....................  31
     Bulletin boards  .................................  33
     Site licenses  ...................................  34
     


















�          BLANK PAGE





















































ARC                                              Page 0
�              INTRODUCTION



     ARC is the copyrighted property of System Enhancement
     Associates, Inc.  You are granted a limited license to
     use ARC, and to copy it and distribute it, provided
     that the following conditions are met:

     1) No fee may be charged for such copying and
        distribution.

                ____
     2) ARC may only be distributed in its original,
        unmodified state.

                ___
     3) ARC may not be distributed, in whole or in part, as
        part of any commercial product or service without
        the express written permission of System
        Enhancement Associates.


     Contributions for the use of this program will be
     appreciated, and should be sent to:

               System Enhancement Associates, Inc.
                  21 New Street, Wayne NJ 07470

     You may not use this product in a commercial
     environment or a governmental organization without
     paying a license fee of $35.  Site licenses and
     commercial distribution licenses are available.  A
     program disk and printed documentation are available
     for $50.  See the order form enclosed with this manual
     for more details.



     ARC is user supported software.  This means that you
     may copy it freely and give the copies away to anyone
     you wish, at no cost.  They are in turn requested to
     send in a contribution if they decide to use it.

     The user supported software concept (often referred to
        _________
     as shareware) is an attempt to provide software at low
     cost.  The cost of offering a new product by
     conventional means is staggering, and hence dissuades
     many independent authors and small companies from
     developing and promoting their ideas.  User supported
     software is an attempt to develop a new marketing
     channel where products can be introduced at low cost.




     ARC                                         Page 1
�If user supported software works, then everyone will
benefit.  The user will benefit by receiving quality
products at low cost, and by being able to "test
drive" software thoroughly before purchasing it.  The
author benefits by being able to enter the commercial
software arena without first needing large sources of
venture capital.

But it can only work with your support.  We're not
                                       ___
just talking about ARC here, but about all user
supported software.  If you obtain a user supported
program from a friend or colleague, and are still
using it after a couple of weeks, then it is obviously
worth something to you, and a contribution should be
sent.



And now, back to ARC:

ARC is used to create and maintain file archives.  An
archive is a group of files collected together into
one file in such a way that the individual files may
be recovered intact.  ARC automatically compresses the
files being archived so that the resulting archive
takes up a minimum amount of space.

When ARC is used to add a file to an archive it
analyzes the file to determine which of three storage
methods will result in the greatest savings.  These
three methods are:

1) No compression; the file is stored as is.

2) Repeated-character compression; repeated sequences
   of the same byte value are collapsed into a three-
   byte code sequence.

3) Dynamic Lempel-Ziv compression;  the file is stored
   as a series of variable size bit codes which
   represent character strings, and which are created
   "on the fly".

Note that since one of the three methods involves no
compression at all, the resulting archive entry will
never be larger than the original file.








ARC                                              Page 2
�                USING ARC



     ARC is invoked with a command of the following format:

         ARC <x> <arcname> [<template> . . .]

     Where:

         <x> is an ARC command letter (see below), in
         either upper or lower case.

         <arcname> is the name of the archive to act on,
         with or without an extension.  If no extension is
         supplied, then ".ARC" is assumed.  The archive
         name may include path and drive specifiers.

         <template> is one or more file name templates.
         The "wildcard" characters "*" and "?" may be used.
         A file name template may include a path or drive
         specifier, though it isn't always meaningful.


     If ARC is invoked with no arguments (by typing "ARC",
     and pressing "enter"), then a brief command summary is
     displayed.



     Following is a brief summary of the available ARC
     commands:

         a   = add files to archive
         m   = move files to archive
         u   = update files in archive
         f   = freshen files in archive
         d   = delete files from archive
         x,e = extract files from archive
         r   = run files from archive
         p   = copy files from archive to standard output
         l   = list files in archive
         v   = verbose listing of files in archive
         t   = test archive integrity
         c   = convert entry to new storage method









     ARC                                         Page 3
�Following is a brief summary of the available ARC
options, which may alter how a command works:

    m   = move files to archive
    z   = include subdirectories in archive
    v   = verbose mode
    b   = retain backup copy of archive
    s   = suppress compression (store only)
    w   = suppress warning messages
    n   = suppress notes and comments
    o   = overwrite existing files when extracting
    5   = produce only level 5 compatable archives
    g   = encode or decode archive entry









































ARC                                              Page 4
�              ARC COMMANDS



     This section describes each of the commands.  ARC will
     accept any one command at a time.  If no commands are
     given, then a brief command list is displayed.



     ____________
     ADDING FILES

     Files are added to an archive using the "A" (Add), "U"
     (Update), or "F" (Freshen) commands.

     Add always adds the file.

     Update differs from Add in that the file is only added
     if it is not already in the archive, or if it is newer
     that the corresponding entry in the archive.

     Freshen is similar to Update, except that new files
     are not added to the archive; only files already in
     the archive are updated.


     For example, if you wish to add a file named
     "TEST.DAT" to an archive named "MY.ARC", you would use
     a command of the form:

         ARC a my test.dat

     If you wanted to add all files with a ".C" extension,
     and all files named "STUFF" to an archive named
     "JUNK.ARC", you could type:

         ARC a junk *.c stuff.*

     If you have an archive named "TEXT.ARC", and you
     wanted to add to it all of your files with an
     extension of ".TXT" which have been created or changed
     since they were last archived, then you would type:

         ARC u text *.txt










     ARC                                         Page 5
�If you have a bunch of files in your current
directory, with backup copies being stored in an
archive named "SAFE.ARC", then if you wanted to make
sure that every file in the archive is the latest
version of that file, you would type:

    ARC f safe


A word about Update and Freshen:  These are similar in
that they look at the date and time of last change on
the file, and only add it if the file has been changed
since it was last archived.  They differ in that
Update will add new files, while Freshen will not.

In other words, Update looks for the files on disk,
and adds them if they are new or have changed, while
Freshen looks in the archive, and tries to update the
files which are already there.


The Add, Update, and Freshen commands may be modified
by the "M" (Move) option.  The Move option tells ARC
to delete the file on disk once it is safely tucked
away in the archive.  For example, if you wanted to
move all files in your current directory into an
archive named "SUM.ARC", you could use a command of
the form:

    ARC am sum *.*

When Move is combined with Update or Freshen, it
deletes the files that are in the archive, even if it
does not need to compress them again.  For example,
suppose you extracted several files from an archive
named "STUFF.ARC" and then made changes to a few of
them.  Now you want to pack away the new versions of
what you changed, and clean up the mess (that is,
delete all the files you extracted).  You can do it
easily by using the command:

    ARC fm stuff


If the Move option is given by itself, it acts like an
"Add and Move".  So in our earlier example of moving
everything in your current directory into an archive
named "SUM.ARC", you could also use the command:

    ARC m sum *.*




ARC                                              Page 6
�     If you don't say which files to add, ARC adds
     everything in your current directory.  So we could
     shorten that to:

         ARC m sum


     Archive entries are always maintained in alphabetic
     order.  Archive entries may not have duplicate names.
     If you add a file to an archive that already contains
     a file by that name, then the existing entry in the
     archive is replaced.  Also, the archive itself and its
     backup will not be added.

     You may also add a file which is in a directory other
     than your current directory.  For example, it is
     perfectly legal to type:

         ARC a junk c:\dustbin\stuff.txt

     You cannot add two files with the same name.  In other
     words, if you have a file named "C:\DUSTBIN\STUFF.TXT"
     and another file named "C:\BUCKET\STUFF.TXT", then
     typing:

         arc a junk c:\dustbin\*.* c:\bucket\*.*

     will not work.


     ARC does not save the path name in this case.  In
     other words, if you specify a drive and/or path when
     adding a file, only the actual file name is stored in
     the archive.

                  ___
     However, you can store a subdirectory in an archive,
     but you have to tell ARC that you want to do that.
     When you add the "Z" option to an Add, Update, or
     Freshen, ARC will store subdirectories and their
     contents in such a way that it can later recreate
     them.

     For example, suppose you have a directory name
     C:\WASTE that you wish to place in an archive named
     "TRASHCAN.ARC".  You could do this with the command:

         ARC az trashcan c:\waste

     This would cause ARC to place the C:\WASTE directory
     (and all of its contents, including any subdirec-
     tories) into the TRASHCAN.ARC archive.  The directory



     ARC                                         Page 7
�is stored in such a way that it can be extracted
anywhere.  It could, for example, be extracted as
D:\JUNKYARD\WASTE if you so desired.

If you combine the "Z" and "M" options, then the
directories are removed from your disk once they are
safely stored in the archive.


ARC will not add an archive to itself, nor will it add
the temporary copy or a backup copy of the archive.


An interesting note:  It has been brought to our
attention that BASIC programs compress to a smaller
                   ___
size when they are not tokenized.  If you are more
concerned with space than speed, you may wish to
convert your BASIC programs to ASCII form before
adding them to an archive.  Your BASIC manual should
give instructions on how to do this.



________________
EXTRACTING FILES

Archive entries are extracted with the "E" (Extract)
or "X" (eXtract) commands.  For example, if you had an
archive named "JUNK.ARC", and you wanted all files in
it with an extension of ".TXT" or ".DOC" to be
recreated on your disk, you could type:

    ARC x junk *.txt *.doc

If you wanted to extract all of the files in an
archive named "JUNK.ARC", you could simply type:

    ARC x junk

Whatever method of file compression was used in
storing the files is reversed, and uncompressed copies
are created in the current directory.

You can also specify a path name, in which case the
decompressed copy is placed in the specified
directory.  For example, if you had an archive named
"JUNK.ARC", and you wanted all files in it with an
extension of ".TXT" to be placed in the directory
"C:\WASTE\LAND", then you could type:

    ARC x junk c:\waste\land\*.txt




ARC                                              Page 8
�     If you wanted to put the file "TRASH.TXT" on your A:
     drive, and the file "LITTER.TXT" on your B: drive, you
     could type:

         ARC x junk a:trash.txt b:litter.txt

     If you give more than one path for a file, then only
     the first one is used.  For example, if you typed:

         ARC x junk a:trash.txt b:trash.txt

     then TRASH.TXT will be placed on your A: drive.



     ______________
     DELETING FILES

     Archive entries are deleted with the "D" (Delete)
     command.  For example, if you had an archive named
     "JUNK.ARC", and you wished to delete all entries in it
     with a filename extension of ".C", you could type:

         ARC d junk *.c



     _______________________
     LISTING ARCHIVE ENTRIES

     You can obtain a list of the contents of an archive by
     using the "L" (List) command or the "V" (Verbose list)
     command.  For example, to see what is in an archive
     named "JUNK.ARC", you could type:

         ARC l junk

     If you are only interested in files with an extension
     of ".DOC", then you could type:

         ARC l junk *.doc


     ARC prints a short listing of an archive's contents
     like this:

         Name          Length    Date
         ============  ========  =========
         ALPHA.TXT         6784  16 May 85
         BRAVO.TXT         2432  16 May 85
         COCO.TXT           256  16 May 85
                 ====  ========
         Total      3      9472



     ARC                                         Page 9
�"Name" is simply the name of the file.

"Length" is the unpacked file length.  In other words,
it is the number of bytes of disk space which the file
would take up if it were extracted.

"Date" is the date on which the file had last been
modified, as of the time when it was added to the
archive.

"Total" is pretty obvious, I think.


ARC prints a verbose listing of an archive's contents
like this:

Name          Length    Stowage    SF   Size now  Date       Time    CRC
============  ========  ========  ====  ========  =========  ======  ====
ALPHA.TXT         6784  Crunched   35%      4413  16 May 85  11:53a  8708
BRAVO.TXT         2432  Crunched   41%      1438  16 May 85  11:53a  5BD6
COCO.TXT           256   Packed     5%       244  16 May 85  11:53a  3AFB
        ====  ========            ====  ========
Total      3      9472             27%      6095


"Name", "Length", and "Date" are the same as for a
short listing.

"Stowage" is the compression method used.  The
following compression methods are currently known:

       --          No compression.

     Packed        Runs of repeated byte values are
                   collapsed.

    Crunched       Lempel-Ziv compression technique
                   employed.

    Squeezed       Huffman encoding compression
                   technique, as employed by an
                   earlier version of ARC.

    Deviant        A nonstandard variant of Lempel-Ziv
                   was employed.  Files compressed
                   with this method should be
                   converted (with the "C" command).

    Subdir         A subdirectory.  The files within
                   the subdirectory may be viewed by
                   using the "Z" option.



ARC                                             Page 10
�     "SF" is the stowage factor.  In other words, it is the
     percentage of the file length which was saved by
     compression.  The total stowage factor is the stowage
     factor for the archive as a whole, not counting
     archive overhead.

     "Size now" is the number of bytes the file is
     occupying while in the archive.

     "Time" is the time of last modification, and is
     associated with the date of last modification.

     "CRC" is the CRC check value which has been stored
     with the file.  Another CRC value will be calculated
     when the file is extracted or tested to ensure data
     integrity.  There is no especially good reason for
     displaying this value.


     ARC follows a verbose listing with a report giving the
     overall compression for everything in the archive and
     for anything specific you selected, along with a
     prediction of whether or not the files would fit on
     your disk if you tried to extract them.

     For example, if you wanted to know if all of the files
     with an extension of ".TXT" in an archive named
     "WASTE.ARC" would fit on your D: drive, you would give
     the command:

         ARC v waste d:*.txt

     At the end of the listing ARC would give its
     prediction of whether or not your D: drive has room
     for those files.



















     ARC                                        Page 11
�_____________
RUNNING FILES

Archive entries may be run without being extracted by
use of the "R" (Run) command.  For example, if you had
an archive named "JUNK.ARC" which contained a file
named "LEMON.COM", which you wished to run, you could
type:

    ARC r junk lemon

You can run any file from an archive which has an
extension of ".COM", ".EXE", ".BAT", or ".BAS".  You
do not have to specify the extension, but all matching
files are run if you do not.  In other words, if you
had an archive named "JUNK.ARC" which contained the
files "LEMON.COM", "LEMON.EXE", and "LEMON.BAS", and
you typed:

    ARC r junk lemon

Then all three programs will be run.  You can avoid
this by specifying an extension in this case.

You can give arguments to the program you are running
by appending them to the command line.  For example,
if you have an archive named "JUNK.ARC" which contains
a program named "LEMON.COM", and you wanted to run it
giving it the argument "JUICE", you would type:

    ARC r junk lemon juice

You will need a fair amount of memory to run a program
from an archive.  It probably cannot be done with less
than 256k.

In practice, the file to be run is extracted, run, and
then deleted.  In other words, the above example is
equivalent to:

    ARC x junk lemon.com
    lemon juice
    erase lemon.com

If you have an archive which contains a program that
you will be running often, then you should probably
extract the program from the archive and use it
normally.







ARC                                             Page 12
�     ______________
     PRINTING FILES

     Archive entries may be examined with the "P" (Print)
     command.  This works the same as the Extract command,
     except that the files are not created on disk.
     Instead, the contents of the files are written to
     standard output.  For example, if you wanted to see
     the contents of every ".TXT" file in an archive named
     "JUNK.ARC", but didn't want them saved on disk, you
     could type:

         ARC p junk *.txt

     If you wanted them to be printed on your printer
     instead of on your screen, you could type:

         ARC p junk *.txt >prn



     __________________
     TESTING AN ARCHIVE

     The integrity of an archive may be tested by use of
     the "T" (Test) command.  This checks to make sure that
     all of the file headers are properly placed, and that
     all of the files are in good shape.

     This can be very useful for critical archives, where
     data integrity must be assured.  When an archive is
     tested, all of the entries in the archive are unpacked
     (without saving them anywhere) so that a CRC check
     value may be calculated and compared with the recorded
     CRC value.

     For example, if you just received an archive named
     "JUNK.ARC" over a phone line, and you want to make
     sure that you received it properly, you could type:

         ARC t junk

     It defeats the purpose of the T command to combine it
     with N or W.












     ARC                                        Page 13
�_____________________
CONVERTING AN ARCHIVE

The "C" (Convert) command is used to convert an
archive entry to take advantage of newer compression
techniques.  This is occasionally desirable when a new
version of ARC is released.  Please refer to the
revision history section for details on when new
compression methods were implemented.

For example, if you had an archive named "JUNK.ARC",
and you wanted to make sure that all files with an
extension of ".DOC" were encoded using the very latest
methods, you could type:

    ARC c junk *.doc

Or if you wanted to convert every file in the archive,
you could type:

    ARC c junk


































ARC                                             Page 14
�               ARC OPTIONS



     This section describes the options which are available
     to modify how ARC works.  Any of these options can be
     combined with any of the commands, though the result
     may not always be something you'd want to do.



     ___________
     DIRECTORIES

     The "Z" option tells ARC that you wish to act on
     directories as well as files.  When combined with Add,
     Update, Freshen, or Move it tells ARC to add
     directories to the archive.  When combined with List
     or Verbose it tells ARC to list directory contents.
     (The Extract command will always extract directories,
     and does not need to be told to do so.)

     A directory is treated as a unit by ARC.  This means
     that when you add a directory to an archive you add
     the whole thing, including all of its files and
     subdirectories.  Likewise, when you extract a
     directory from an archive you get all of it.

     If you wish to make a change to a directory that is in
     an archive, you should extract it, then make whatever
     changes you want on disk, and then put the directory
     back into the archive.



     _____________________
     LEVEL 5 COMPATIBILITY

     The "5" (level 5 compatibility) option can be combined
     with any comand that alters an archive.  It tells ARC
     that the resulting archive should be fully compatible
     with ARC version 5.  This is mostly necessary for
     creating archives that are to be extracted on other
     operating systems where the version of ARC available
     for that system does not yet support the ARC version 6
     extensions.

     When given the level 5 compatibility option, ARC will
     ensure that the resulting archive does not contain any
     directories, comments, or any extended data fields for
     non-MS-DOS operating systems.





     ARC                                        Page 15
�____________
VERBOSE MODE

The "V" (Verbose) option can be used with any command,
though it isn't always meaningful.

When used with the List command it causes ARC to
display a "verbose listing" of the archive contents.
In fact, this is its most common use, so you can use
the Verbose option as a command for this purpose.

When used with any command that creates a new archive
(generally during an Add or a Move), it tells ARC to
add a note to the archive saying which version of ARC
created the archive.  This note is then automatically
updated every time the archive is modified, and is
displayed during a verbose listing.

Normally when ARC adds files to an archive or deletes
files from an archive it doesn't say anything about
the files it isn't changing.  When you use the verbose
option ARC will report them.



________________
BACKUP RETENTION

When ARC changes an archive (during an Add, Move,
Update, Freshen, Delete, or Convert) it creates a new
archive with the same name, but with an extension of
".$$$".  For example, if you add a file to an archive
named STUFF.ARC, then ARC will create a new archive
named STUFF.$$$.  ARC will read from your existing
archive and write out the new archive with any changes
to the ".$$$" copy.

Normally when ARC is finished it deletes the original
and renames the new archive to the original name (ie.
STUFF.ARC goes away, and STUFF.$$$ becomes the new
STUFF.ARC).  Among other things, this means that if
anything goes wrong and ARC is unable to finish, then
your original archive will still be intact.


In some circumstances you may wish to retain the
original version of the archive as a backup copy.  You
can do this easily by using the Backup option.  Add
the letter "B" to your command, and ARC will rename
your original archive to have an extension of ".BAK"
instead of deleting it.





ARC                                             Page 16
�     In other words, if you wanted to add "WASTE.TXT" to an
     archive named "JUNK.ARC", but wanted to keep a backup
     copy, then you would type:

         ARC ab junk waste.txt

     Your original archive would become "JUNK.BAK", while
     "JUNK.ARC" would contain the new "WASTE.TXT" file.


     If you keep a backup of an archive which already has a
     backup, then the older backup copy is deleted.



     _______________________
     SUPPRESSING COMPRESSION

     The "S" (Suppress compression) option can be combined
     with any command that updates archive entries.  These
     include Add, Move, Update, Freshen, and Convert.  The
     effect of the S option is to prevent any compression
     techniques from being employed.  This is intended to
     allow you to add a few files at a time to an archive
     quickly, and then later convert the archive to
     compress everything at once.

     For example, over the course of a day you might give
     each of the following commands:

         ARC as junk *.txt
         ARC as junk *.mac
         ARC as junk *.doc

     At the end of the day, when you have finished adding
     things to the archive, you could have all of the
     archive entries compressed at once by typing:

         ARC c junk

     You could also decompress the archive by typing:

         ARC cs junk

     though I can't imagine why you'd want to.










     ARC                                        Page 17
�___________________
MESSAGE SUPPRESSION

ARC prints three types of messages: warnings,
comments, and errors.

Warnings are messages about suspected error
conditions, such as when a file to be extracted
already exists, or when an extracted file fails the
CRC error check.  Warnings may be suppressed by use of
the "W" (Warn) command.  You should use this command
sparingly.  In fact, you should probably not use this
command at all.

Comments (or notes) are informative messages, such as
naming each file as it is added to the archive.
Comments and notes may be suppressed by use of the "N"
(Note) command.

Errors are actual system problems, such as running out
of disk space.  You cannot suppress errors.


For example, suppose you extracted all files with an
extension of ".BAS" from an archive named "JUNK.ARC"
Then, after making some changes which you decide not
to keep, you decide that you want to extract them all
again, but you don't want to be asked to confirm every
one.  In this case, you could type:

    ARC xw junk *.bas

Or, if you are going to add a hundred files with an
extension of ".MSG" to an archive named "TRASH.ARC",
and you don't want ARC to list them as it adds them,
you could type:

    ARC an trash *.msg

Or, if you want to extract the entire contents of an
archive named "JUNK.ARC", and you don't want to hear
anything, then type:

    ARC xnw junk


A special case is provided when extracting files from
an archive.  One of the various warnings that can
occur is when a file being extracted already exists on
disk.  Normally, ARC will stop and ask you if you want
to overwrite the file.  This can be suppressed with
the "W" command, but that will also suppress any



ARC                                             Page 18
�     warnings about other things, like failed CRC checks
     and such.

                                           ____
     The "O" (Overwrite) option suppresses only the warning
     that the file already exists.  For example, in our
     earlier case of extracting all the ".BAS" files from
     "JUNK.ARC", a much safer way to do it is to type:

         ARC xo junk *.BAS



     _____________________
     ENCRYPTION/DECRYPTION

     Archive entries may be encrypted and decrypted by
     using the "G" (Garble) option.  The Garble option
     takes the remainder of the command string as the
                                        ____
     password to use, so it must be the last option.


     For example, if you wanted to add a file named
     "WASTE.TXT" to an archive named "JUNK.ARC", and you
     wanted to encrypt it using the password "DEBRIS", then
     you would type:

         ARC agdebris junk waste.txt

     Later on, when you want to extract it again, you would
     type:

         ARC xgdebris junk waste.txt

     The password you supply is used to encrypt (or
     decrypt) the archive entry by performing an exclusive
     OR between each byte of the packed data and each byte
     of the password.  The password can be any length, and
     each of its bytes is used in rotation.  The password
     is converted to uppercase before it is used, so it is
     ___
     not case sensitive.  Since the encryption is performed
     on the packed data, it has no effect on stowage
     factors.

     This is not a particularly sophisticated means of
     encryption.  Still, since it is performed on the
     packed data, the result should be quite sufficient for
     casual use.








     ARC                                        Page 19
�You can, if you wish, use different passwords for
different files in an archive, but we advise against
it.  If you are going to encrypt an archive, we
suggest you use the same password for every file, and
give the password whenever you do anything at all with
the archive.  It is possible to list the entries in an
encrypted archive using the "L" and "V" commands
without giving the password, but nothing else will
work properly.


We advise that you use this option sparingly, if at
all.  If you should forget or mistype your password,
it is highly unlikely that you will ever recover your
data.







































ARC                                             Page 20
�               INDIRECTION



     The list of filenames given to ARC may include
     indirect references.  If a filename begins with an "at
     sign" ("@"), it is taken to be the name of a file
     which contains a list of file names.  The list of file
     names may include further indirection.  For example,
     the command:

         arc a waste junk.txt @trash

     would cause ARC to add JUNK.TXT plus all files listed
     in the file TRASH to an archive named WASTE.ARC.  If
     no file is specified, then the list is read from
     standard input.

     When the N option (suppress Notes) is used with the L
     (List files) command, it causes a terse listing of
     filenames only, suitable for use with pipes and
     redirection.  This can be combined with indirection to
     easily perform many tasks.

     For example, the command:

         arc ln waste | arc a trash @

     would cause ARC to add files to TRASH.ARC based on the
     names of the files stored in WASTE.ARC.

     If by some chance you want to archive a file whose
                 ____
     name really does begin with an at sign, then preceed
     the name with a forward slash ("/").  For example, to
     add a file named "@DUST.DAT" to an archive named
     "TRASHCAN.ARC", you would type:

         arc a trashcan /@dust.dat


     The MARC program also allows for indirection.













     ARC                                        Page 21
�        RAMDISK SUPPORT



If you have a RAMdisk, or other high-speed storage,
then you can speed up ARC somewhat by telling it to
put its temporary files on the RAMdisk.  You do this
by setting the ARCTEMP environment string with the
MS-DOS SET command.  For example, if drive B: is your
RAMdisk, then you would type:

    set ARCTEMP=B:

Refer to the MS-DOS manual for more details about the
SET command.  You need only set the ARCTEMP string
once, and ARC will use it from then on until you
change its value or reboot your system.


If ARC does not find an environment string named
ARCTEMP, then it looks for one named TEMP to use
instead.  Several packages already use the TEMP string
for exactly this purpose.  If you have need of an
environment string named TEMP for something else, then
you should be sure to define ARCTEMP.


There are a limited number of temporary files created
by ARC.  The Convert command uses a file named
"$ARCTEMP.CVT" to hold each file as it is being
converted.  The Run command also creates a temporary
file, which has the name "$ARCTEMP", and whose
extension matches that of the file being run.





















ARC                                             Page 22
�             VERSION NUMBERS



     There seems to be some confusion about our version
     numbering scheme.  All of our version numbers are
     given as a number with two decimal places.

     The units indicate a major revision, such as adding a
     new packing algorithm.

     The first decimal place (tenths) indicates a minor
     revision that is not essential, but which may be
     desired.

     The second decimal place (hundredths) indicates a
     trivial revision that will probably only be desired by
     specific individuals or by die-hard "latest version"
     fanatics.

     ARC also displays its date and time of last edit.  A
     change of the date and time without a corresponding
     change in version number indicates a truly trivial
     change, such as fixing a spelling error.


     To sum up: If the units change, then you should get
     the newer version as soon as you can.  If the tenths
     change, then you may want to get the newer version,
     but there's no hurry.  If anything else changes, then
     you probably shouldn't bother.























     ARC                                        Page 23
� COMMON QUESTIONS AND ANSWERS



Here are some of the more common questions we've
received about ARC, along with their answers:


Q: Why does ARC run out of room if I make an archive
   bigger than about 180k?

A: Because you are working on a floppy disk.  ARC
   creates a copy of your archive, incorporating any
   new files as it goes.  When it is done, it deletes
   the original and renames the new one.  There are a
   number of reasons for doing it this way, one being
   that your original archive is still intact if
   anything happens while ARC is running.

   You can save some space by using drive specifiers
   and having the archive and the files to add on
   separate disks, but you still won't be able to make
   an archive larger than about 180k.  If you need to
   make a larger archive, and if you have a fixed
   disk, then you can create the archive on the fixed
   disk and then copy it to the floppy.


Q: I've seen an ARC.COM and an ARC.EXE.  Which one is
   the right one?

A: ARC.EXE.  One or more people have been running ARC
   through a utility that converts an ".EXE" file to a
   ".COM" file.  But this utility is designed to save
   _____
   space, not speed.  On ARC it saves about 250 bytes,
   and makes no measurable difference in program
   speed.  We've decided that the savings are not
   worth the extra step in development in this case.


Q: How can I get the latest version of ARC?

A: ARC updates are distributed through normal
   shareware channels.  We also ship a program update
   disk on every order of $50 or more.  Also, please
   refer to the next section for information about our
   maintenance contracts.







ARC                                             Page 24
�     Q: Can I distribute my public domain or shareware
        program in an ARC format archive?

     A: Yes, of course.


     Q: Can I use ARC to distribute my commercial software
        package?

     A: Yes, provided that you obtain a commercial
        distribution license from us.  Please contact us
        for details.


     Q: Why not allow me to select which method of
        compression I want ARC to use?

     A: It would needlessly complicate ARC, both internally
        and in use.  The exact nature of the compression
        methods used are complex, and quite different.  The
        only sure way to tell which will be best in any
        given case is to analyze the data, as ARC does.
        The method chosen may not always be what you
        expect.


     Q: ARC keeps giving me an odd error message.  It says
        "Drive not ready.  Abort, Retry, Ignore?"  What
        does this mean?

     A: Close the latches ("doors") on your floppy disk
        drives, then press the "R" key.


     Q: How can I tell ARC to make an archive that goes on
        more than one floppy disk?

     A: Create the archive on your fixed disk, and then use
        the BACKUP command (or other backup utility).















     ARC                                        Page 25
�     MAINTENANCE CONTRACTS



Registered users of ARC receive 30 days of telephone
support at no extra charge.  If you wish, you can
extend this by purchasing a maintenance contract.

A maintenance contract costs $50 per year.  In
addition to telephone support you also receive free
updates to ARC as soon as they are available, and a
                     ______ _____
free subscription to Making Waves, the SEA customer
support newsletter.









































ARC                                             Page 26
�            REVISION HISTORY



     ____________________
     CHANGES IN VERSION 5

     The Move command used to delete the files as it went.
     It now waits until it is finished updating the
                                                  ___
     archive, and deletes them all at once.  (You did know
     that Move is just an Add where the file gets deleted,
     didn't you?)  This, along with the changes made in
     version 4.5, means that it is now much safer to
     interrupt ARC while it is working.

     The Print command no longer prints the name of each
     file.  Instead, it prints a formfeed after each file.

     The Run command now supports BASICA programs.  Also,
     the filename extension is no longer required on the
     Run command.

     The Garble option was added.  It provides a convenient
     means of low level data security for the casual user.
     Use it sparingly, if at all.

     ARC no longer tests for the presence of $ARCTEMP.CRN
     before creating a new one.  If you interrupt ARC a
     lot, you'll find this much more convenient.  If you
     happen to have a file named $ARCTEMP.CRN which you
     want to keep, too bad.

     Improved error recovery was added when reading an
     archive.  ARC now has a good chance of recovering the
     data from a corrupted archive (the corrupted entry is
     still lost, of course).

     Path support has been added for all commands, though
     it doesn't do anything on most of them.  For example,
     there isn't much we can do with a path in the List
     command.  But many users will be glad to know that a
     path can be used when extracting a file, and specifies
     where the file is to be placed.

     Support for the TEMP environment string was added.  If
     ARC doesn't find an environment string named ARCTEMP,
     then it looks for one named TEMP to use instead.
     Several packages already use the TEMP string for
     exactly this purpose.






     ARC                                        Page 27
�ARC is now using a different variation of Lempel-Ziv
coding, courtesy of Kent Williams, who found it on
USENET and adapted it to the IBM PC.  The new method
differs from the old in several respects.  The most
significant differences are:

1) Where our previous implementation used a fixed code
   size of twelve bits, the new one starts with a code
   size of nine bits and increases it as it needs to.

2) The earlier method tended to "choke" on large files
   when its string table filled up.  The new method
   has a rather ingenious scheme its authors call
   ______________
   adaptive reset.  When it notices that its string
   table has filled, and its compression ratio is
   starting to suffer, it clears the table and starts
   defining new strings.

The previous implementation of Lempel-Ziv coding is no
longer used to pack files.  The "V" (Verbose listing)
command distinguishes between the two by referring to
the older method as "crunched" (with a lower-case
"c"), and the newer method as "Crunched" (with a
capital "C").

Rick Moore discovered that ARC was occasionally adding
an archive to itself.  This would only happen when the
archive is in the same directory as the files being
added, and its name comes last.  This bug has been
fixed, though it is still possible to fool ARC into
adding an archive to itself by getting tricky with
path names.

Dana Montgomery found the upper limit on how many
files can be added to an archive.  There's always been
an upper limit, but it depends on memory, and used to
be larger than anyone could possibly want (knock on
wood).  However, the added memory requirements as of
version 5.0 lowered this limit into the realm of
possibility, somewhere around 300 files.  We change
some things around, and effectively, there is no
longer a limit on how many files you can add at once.
ARC will add the files in batches of as many as it can
handle at one time.

The Run command has been modified to allow passing
command line arguments to the program being run.

Indirection was added, and the List command was
modified to give a terse listing suitable for use with
indirection when the N option is employed.



ARC                                             Page 28
�     A bug was found that would keep an archive entry from
     being encrypted if it was stored without compression.
     This has now been fixed.

     If changes are made to a corrupted archive, the
     corrupted entries are discarded.  This makes it
     possible to lose data accidentally.  ARC will now only
     make changes to a corrupted archive if the W (suppress
     Warnings) option has been given.

     Support for a nonstandard variation of Lempel-Ziv was
     added.

     Two new utilities, SCANDISK and SQDIR, were added to
     the ARC program disk.  Full program sources for both
     are included in UNDEL.ARC on the ARC source disk.



     ______________________
     CHANGES IN VERSION 5.3

     A minor bug caused earlier versions of ARC to output
     an extra carriage return on an end of line when
     dumping text to standard output with the "P" command.
     This has now been fixed.

     Greatly enhanced error recovery has been added to deal
     with corrupted or partially damaged archives.  The
     corrupted data itself is still lost, of course, but
     ARC will recover everything possible.

     ARC has been fully ported to Microsoft C version 5.1.
     This has resulted in a small speed improvement, and
     should make it easier to port ARC to other operating
     systems.

     A new utility, MKSARC, was added to the ARC program
     disk.  Regretfully, we cannot release the program
     sources for MKSARC.



     ______________________
     CHANGES IN VERSION 6.0

     Version 6.0 is a major upgrade for ARC.  It is a
     substantial rewrite that greatly improves overall
     performance.  ARC is now as fast as any comparable
     program, or faster.  The changes are primarily in
     internal organization of the code, so that versions
     ported to other operating systems should experience a
     substantial performance boost as well.



     ARC                                        Page 29
�We've also added support for directories, allowing
entire directory trees to be added or moved into an
archive, and later extracted.

We've also designed and implemented a method whereby
versions of ARC ported to other operating systems can
record system-specific information in a compatible
manner.  This includes provisions for longer
filenames, more date/time stamps, and even icon
bitmaps.  Contact us for details or see the comments
in the ARC sources if you are interested in using this
capability in a version of ARC for a different
operating system.









































ARC                                             Page 30
�       PROGRAM HISTORY AND CREDITS



     In its short life thus far, ARC has astounded us with
     its popularity.  We first wrote it in March of 1985
     because we wanted an archive utility that used a
     distributive directory approach, since this has
     certain advantages over the then popular central
     directory approach.  We added automatic squeezing in
     version 2 at the prompting of a friend.  In version
     2.1 we added the code to test for the best compression
     method.  In less than a year we found that our humble
     little program had spread across the country, and
     seems to have become a new institution.

     We are thankful for the support and appreciation we
     have received.  We hope that you find this program of
     use.


     If we have achieved greatness, it is because we have
     stood upon the shoulders of giants.  Nothing is
     created as a thing unto itself, and ARC is no
     exception.  Therefore, we would like to give credit to
     the following people, without whose efforts ARC could
     not exist:


     Brian W. Kernighan and P. J. Plauger, whose book
     "Software Tools" provided many of the ideas behind the
     distributive directory approach used by ARC.

     Dick Greenlaw, who wrote the public domain SQ and USQ
     programs, in which the Huffman squeezing algorithm was
     first developed.

     Kent Williams, who graciously allowed us to use his
     LZWCOM and LZWUNC programs as a basis for our Lempel-
     Ziv compression logic, and who continues to make
     valuable contributions.

     David Schwaderer, whose article in the April 1985
     issue of PC Tech Journal provided us with the logic
     for calculating the CRC 16 bit polynomial.

     Terry A. Welch, whose article "A Technique for High
     Performance Data Compression", IEEE Computer Vol 17 No
     6 (June 1984) seems to have started all the research
     on Lempel-Ziv coding.




     ARC                                        Page 31
�Spencer W. Thomas, Jim McKie, Steve Davies, Ken
Turkowski, James A.  Woods, and Joe Orost, who are the
authors of the UNIX compress utility.

Karl Schinke, who is the friend that suggested that we
add compression to ARC.

Alex Jacobs, who in June of 1985 sent us the very
first shareware contribution we ever received.


And many, many others whom we could not identify.










































ARC                                             Page 32
�             BULLETIN BOARDS



     ARC is distributed mainly through shareware channels.
     Among other things, this means that ARC is available
     from many bulletin board systems.  In fact, the system
     operators (sysops) of many bulletin boards have taken
     to storing almost all of their downloadable files in
     archives to save themselves disk space and to save
     their users time.

     This also makes things more convenient for the
     bulletin board users, since one archive may contain
     several programs, any related data files, and the
     documentation.  Many shareware authors have taken to
     distributing their software in archives to help ensure
     that the users receive everything.

     Obviously, we can't do that with ARC.  As a result,
     many of our users have ARC, but don't have the manual.
     Most of our customer support calls come from people
     who have never seen the manual, and in many cases
     didn't even know that one exists!

     To solve this problem we developed what is in essence
     a self-unpacking archive.  We distribute this as
     "ARCxxx.EXE", where "xxx" is the current version
     number.  For example, ARC version 6.00 would be
     distributed as "ARC600.EXE".  This program, when run,
     unpacks itself into a copy of ARC plus its
     documentation.

     Now that we've gone to all that work, we'd really
     appreciate it if you would use this program when you
     distribute ARC.


















     ARC                                        Page 33
�         SITE LICENSES



Corporate users may wish to obtain a site license for
the use of ARC.  Please use the order form in this
manual to order a site license.  Site licenses are
granted as of when we receive your payment.  License
fees vary depending on the number of computers on
which ARC will be used, as follows:


             1 machine            $50
     2  to   9 machines           $35 per machine
    10  to  24 machines           $25 per machine
    25  to  49 machines           $20 per machine
    50 or more machines           $15 per machine

    100 or more machines at one location    $1500



Enclosed is a site license agreement, which should be
signed and sent with your payment when ordering a
commercial site license.


A commercial site license does not include additional
copies of the ARC program disk and the ARC manual.
Instead, you make your own copies of the disk and
manual as you need them.  If you wish, you can order
additional program disks and manuals from us.






















ARC                                             Page 34


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