OS/2 Shareware BBS: 9 Archive/09-Archive.zip/arj2_275.exe/arj/readme.txt

Text File | 2000-12-31 | 18KB | 402 lines

   ARJ for OS/2, version 2.75                           December, 31, 2000


   LEGAL NOTICE

      No warranties of any kind are made. In no  event should ARJ Software
      Russia be liable for any damage resulting from use or misuse of this
      product.

      You  have a royalty-free  right to distribute  this  product  in any
      form.  Commercial  use of  this  product  must be  approved  by  ARJ
      Software, Inc.

      The  information in  this document is  a subject  to change  without
      notice.


   INTRODUCTION

      To meet  the data  archiving  needs, ARJ Software  Russia delivers a
      range of its own  products based  on the code of  original ARJ. From
      the  beginning,  our  goal  was  to  retain  the  functionality  and
      compatibility with  the  original ARJ  for DOS, but we  also provide
      features  and  enhancements  that  are a  must for certain  tasks or
      certain platforms where no ARJ has been before.


   NEW FEATURES AND DIFFERENCES FROM THE ORIGINAL ARJ

      ("-" indicates a  missing feature, "*" - a different  operation and
       "+" stands for a feature unique for our implementation)

      -  There may be a  significant  performance drawback  when accessing
         files on volumes with no write-back cache.

      *  The "-hm" options  are  compatible  with their ARJ implementation
         hence  a  temporary  swap  file  is  created  if  the  file  list
         exceeds  3000  files.  To keep  the  entire list  in  memory, use
         -hm65000. This  is  useful if you are running  a non-DOS version,
         have  an   adequate  amount  of   RAM  and   therefore   are  not
         constrained with RAM occupied by file lists.

      +  The "-ha" has been improved. Now, when  used  in conjuction  with
         an archiving  command, it does  not mark read-only  files as such
         in archive.  This simplifies  archiving from  CD-ROM media  where
         virtualized read-only  attribute  is  forced  by  respective IFS
         driver.

      +  The "-h#" option  has been  improved to  allow  custom  date/time
         formats.  A  custom  format  is  specified  by  putting a  format
         sequence   right   after  the "-h#".  The  following   characters
         represent date/time macros:

          Y = year,       M = month,      D = day
          h = hour,       m = minute,     s = second
          N = day of year

          (note that these are case-sensitive)

         All  other  characters,  as  well as  those going  beyond  format
         limits (4  digits for year, 2 digits for all  other fields),  are
         treated as delimiters. Examples:

         ARJ a project- -h#YYYYMMDD              (project-19991022.arj)
         ARJ a backup- -h#MM-DD_hh-mm-ss    (backup-10-22_23-57-16.arj)
         ARJ a specs -h#YY                                (specs99.arj)
         ARJ a logs_ -h#NNN                              (logs_295.arj)
         ARJ a test -h#YYYYYYYY                      (testYYYY1999.arj)

      +  "-2k" option forces 2-digit display of year in lists. This can be
         be helpful  if the  3-digit year  format  used for  dates  beyond
         2100 is confusing.

         Alternatively, "-2k1" uses a non-ambigous  format  that  is  both
         easy to read and  information-packed.  The dates are  represented
         by two digits if  the year  is 1970 to 2069, and in three  digits
         if it's 2070 or beyond.

      +  The  "-2a"  option  is  implemented  in  ARJ  due  to  a  popular
         demand from  FidoNet system  operators.  Basically it  acts  like
         "-jo",  with   the   exception  that  file  names,  and  not  the
         extensions,  are  "serialized". Consider  having  a  file  called
         "FILE995N.TXT" and  an archive that contains  the  same  file. If
         extracted  with  the "-2a"  option,  the  file  will  be  written
         to  "FILE9950.TXT", if  you extract it  again,  it'll  be  called
         "FILE9951.TXT",  and   so   on   up   to   "FILE9959.TXT",   then
         "FILE9960.TXT". And  after  "FILE9999.TXT" ARJ  will  start  with
         "FIL00000.TXT". This option allows you  to extract  one  file  to
         100000000  unique  names.  It's  essential  to  system  operators
         since multiple mail  packets with  the same  name may  come  from
         different systems.

         NOTES:
           1. It'll be wise to  include  this  option in the  script  that
              unpacks the ARCmail  packets and  NOT  in ARJ_SW environment
              variable. This  option is  a  security  measure  for systems
              running in  unattended  mode, and  will  only confuse you if
              enabled by default.
           2. There's a security  hole: a file  called  "9999.XXX" or  so,
              will not  be  overwritten.  However, all  subsequent  writes
              will be  redirected  into  file  "0000.XXX". So, files  with
              9s in the beginning have  less  chances of being  preserved.
              Hopefully such situation is unlikely for FidoNet systems.
           3. There is  another  option, "-jo1", to  serialize  filenames,
              however  its   operation   is  different.  The  volume  must
              support  long  filenames  in   order  to  use  this  option,
              moreover,  it's  not   suitable  for  dealing  with  FidoNet
              ARCmail.

      +  With no ARJ_SW  specified, ARJ  looks for  a file  named  ARJ.CFG
         in its home  directory. If found, this file  will  be parsed  and
         used  as  a  standard  ARJ  configuration  file (see  manual  for
         details).


   EXTENDED ATTRIBUTES HANDLING

      Beginning  with  version  2.62.10,  the  extended  attributes  (also
      referenced to  as  EAs) can  be  backed  up  and   restored  without
      needing  any external  utilities. This is  achieved  by  compressing
      and storing EAs as a part of file header.

      Restrictions on EA support:

      *  The multivolume restart  feature (-jn) will not  work  if EAs are
         enabled. You'll  have to  disable EAs  with -2d  prior  to  using
         -jn, or to recreate the archive if the EAs are precious.

      *  Hollow mode archives do not support EAs.

      A set of new options has been introduced to let  the user control EA
      handling:

      *  "-2c" restricts  EA  handling  to  critical  EAs  only.  Archived
         non-critical  EAs  will not  be  restored.  When  an  archive  is
         created, only critical EAs will be saved.

      *  "-2e" specifies EA inclusion  filter. With no  parameters  given,
         it disables EA  handling at  all. Otherwise, an  expression  that
         follows  it  is  interpreted  as  a   wildcard  that   limits  EA
         inclusion to a  particular EAs. Multiple  options can be  entered
         to represent a set of EA names but list files are not allowed.
         Examples:

         ARJ a test

         In this example, all EAs will be preserved.

         ARJ a no_eas -2e
         ARJ x no_eas -2e

         EAs will neither be packed nor restored.

         ARJ a documents -2e.LONGNAME

         In this case, only .LONGNAME EAs will be handled.

         ARJ a test -2e.CLASSINFO -2e.ICON*

         .CLASSINFO and .ICON* (i.e. .ICON, .ICON1, .ICONPOS) EAs  will be
         be packed and restored.

         It's wise  to specify "-2e.*" when backing up  your OS/2  desktop
         or  configuration  files.  The system  EAs  start with  dot (".")
         while application EAs start with application name.

      *  "-2l" allows to  convert  .LONGNAME  extended  attributes  (these
         represent icon titles used in  WPS) to file names, when possible.
         This feature  simplifies moving document  files away from an OS/2
         system installed on a FAT volume.

         If  the icon  title (and  so  the  extended  attribute)  contains
         line breaks, wildcard characters  or other symbols, real filename
         will be used instead and the .LONGNAME EA will be preserved.

         This option is ignored during extraction. "-2e" and "-2x" have no
         effect  on  this  option  (but  .LONGNAME EAs are  not  saved  if
         .LONGNAME EA handling is implicitly or explicitly disabled).

      *  "-2x" specifies an  exclusion  filter. It must be followed  by an
         exclusion  EA name  specification. The  rules  are  the  same  as
         with "-2e". Also, the  two options  may  work together, providing
         both an inclusion and an exclusion rule. For example:

         ARJ a backup_ -r -p1 -h#2 -2e.* -2x.FED* c:\projects

         may be used to  create  regular back-ups of your  work directory,
         including all system EAs  but  excluding  EAs  created  with FED
         (Fast Editor  Lite, an  editor written  by Sergey I. Yevtushenko,
         [e-mail]) - that program  does not follow traditional
         EA naming  conventions  and  uses  system-alike  EAs  for  anchor
         position marks.

      Extended  attributes are  also  supported in ARJSFXV self-extractors
      where they are stored using the  same  technology as with  usual ARJ
      archives.

      The presence of EAs  is  indicated  by a "(EA: ...)" message when  a
      file is packed. Note that this size  may differ from  the one  given
      when the file  is unpacked - the  former is  the EA  structure  size
      and the latter is the space allocated  for EA storage. The number of
      EAs and the size of EA structure is  also displayed when the archive
      is listed with "ARJ v" command.


   FREQUENTLY ASKED QUESTIONS

      Q: Third-party applications fail to handle ARJ/2 archives!
      A: Try to disable extended attributes (-2e) and HPFS DTA/DTC storage
         (-j$). Many applications  are incapable  of handling new  archive
         format (although  this format is fully compliant with  documented
         guidelines). Known  examples  of such  applications  include File
         Commander v 2.11, Norton Commander v 5.00 and WinRAR v 2.60.

      Q: Extended  attribute  sizes  reported  by InfoZIP  and  ARJ/2  are
         different. What's the cause?
      A: As  we  have  stated  earlier,  ARJ/2  reports  the  size of  its
         internal EA  storage structure  as EA  size  when  packing files.
         This may mismatch with  space allocated for EAs  by  the  system,
         and it may  also  mismatch  with  values  reported by other  OS/2
         native archivers.

      Q: How can I back up my OS/2 Workplace Shell folders, preserving the
         icons?
      A: Since  folders are  represented  with directories, you'll have to
         enable directory storage with -a1 or -hbfd.

      Q: What is ARJLX?
      A: It's the same program as  ARJ/2, compressed  with LXLITE utility.
         It requires  OS/2  v 3.0 or  higher  to  run. You  may  encounter
         some  compatibility problems  with  it (it's unable  to  register
         ARJLX with REGISTER.EXE, and so on...)

      Q: The EAs have vanished after I used ARJ/DOS to update an archive.
      A: Current versions  of ARJ/DOS and ARJ32, as well as ARJ/2 prior to
         2.62.10, strip  the  extended  headers when  any kind  of archive
         update occurs.

      Q: I want  to  create  single-volume  self-extracting  archive  that
         supports EAs but ARJ/2 uses ARJSFX instead of ARJSFXV.
      A: You need to  force  use of  ARJSFXV/2. The best way for  it is to
         specify an arbitrary large value for volume size, e.g. -va.

      Q: How can I create an installer for my OS/2 product with ARJ?
      A: ARJSFX/2 is  able  to run OS/2  commands after unpacking archive.
         Try this: create a  script you want  to to be  invoked  after the
         installation completes.

         e.g., INSTALL2.CMD:
         =======
          /* REXX */

          if RxFuncQuery('SysLoadFuncs') then do
           call RxFuncAdd 'SysLoadFuncs', 'RexxUtil', 'SysLoadFuncs'
           call SysLoadFuncs
          end

          say "Installation has completed, creating desktop object..."
          call SysCreateObject ....
         ========
         and so on...

         Now create an archive comment with the first line as follows:
         )) \InstallDir\ -b -x -y -!INSTALL2.CMD

         Call it, for example, CMT.ANS. Now create an ARJSFX archive:

         ARJ a PACKAGE.EXE -je -r -a -jm -zCMT.ANS -xCMT.ANS

         You'll make  a  self-extracting  archive  with  an  automatically
         invoked installation program.

         You may not commercially distribute these packages.

      Q: How can I distinguish ARJ/2 archives from ARJ/ARJZ ones?
      A: Use the ARJ V  command. The "Host OS" field contains  the type of
         host OS. The  "Revision"  field  may  be used  to  determine  the
         archiver version that added the file:

                 1 = ARJ versions earlier than 0.14,
                     ARJZ compatibility mode (-md is less than 26624)
                 2 = ARJ v 0.14...0.20
                 3 = ARJ v 1.00...2.22
                 4 = ARJ v 2.30, X1
                 5 = ARJ v 2.39a, 2.39b
                 6 = ARJ v 2.39c...2.41
                 7 = ARJ v 2.42a...2.50a
                 8 = ARJ v 2.55...2.61, ARJ/2 v 2.61
                 9 = ARJ v 2.62, ARJ/2 v 2.62, ARJ32 v 3.00
                10 = ARJ v 2.70 and higher, ARJ/2 v 2.62.10 and higher
                50 = ARJZ with maximum distance up to 32K
                51 = ARJZ with maximum distance up to 64K
               100 = ARJ32 v 3.00b...3.01
               101 = ARJ32 v 3.02 and higher

         Note: ARJ versions  that  created  the  Revision 1  header used a
         different method 4  compression. Support for  it  was dropped  in
         versions 1.xx. Such  archives  may  be  incorrectly  processed by
         ARJ/2.


   INFORMATION FOR DEVELOPERS

      The header format  is 100% compatible  with standard  ARJ format but
      we  were the first to  make  use  of extended  header fields. Here's
      a brief  summary of  the EA storage  technology. First, the extended
      header layout is as follows (all values are little-endian):

      Bytes  Description
      -----  -----------
          1  Extended header  ID (0x45, the  character  'E'). Indicates
             a EA information header. This is only valid if the arj_nbr
             (header revision number) is 10 or greater.
          1  Continuation  flag. If set to  0, marks the  end of  block
             chain so the  EA data  can be concatenated  and  unpacked.
             Also it provides a way of checking for trashed EA blocks.
          ?  Packed EA block.

      A standard CRC32 of the whole header, including the ID but excluding
      header size field,  is  appended to  it. It is strongly  recommended
      that the CRC is verified when any compressed EA processing occurs.

      The packed  EA  block is a  complex  structure  that  can span  over
      multiple  volumes. In  case of  such  spanning,  separate  parts  of
      the block  are stored  in  separate extended  headers  on  different
      volumes and they must be joined together when the last block is read
      (it's recognized   by  EXTFILE_FLAG being clear). The layout of  the
      packed block follows:

      Bytes  Description
      -----  -----------
          1  Compression method (0...4, may differ from the  one found  in
             the file header)
          2  Unpacked EA data size in bytes
          4  CRC32 of unpacked EA data
          ?  Raw packed EA data

      The raw  packed data  may  be decompressed  using the  original  ARJ
      algorithms. In the case when the file is encrypted, the packed block
      is also  encrypted (but the  garble  routine is  reinitialized  when
      compression  of the EA occurs). The password modifier is the same as
      for the  first file section. After  decompression, the  following EA
      structure will exist:

      Bytes  Description
      -----  -----------
          2  Total number of EA records
          ?  Extended attribute records

      The extended attribute records are merged altogether. They should be
      processed  sequentally. A single record  represents a single EA, and
      no EA can be represented twice. The layout is as follows:

      Bytes  Description
      -----  -----------
          1  fEA byte (may indicate a critical EA)
          1  Size of extended attribute name
          2  Size of extended attribute value
          ?  Extended attribute name (not ASCIIZ)
          ?  Extended attribute value (binary data)

      Even if the file is  a text  one, the EAs must be  handled as binary
      data during  compression and  extraction. When EAs are spanned  over
      multiple volumes, neither  the packed  block header  is repeated nor
      the compression  is  restarted (actually, the whole block  including
      its header is created in memory and later split to volumes).


   PRODUCT INFORMATION

      This program has been developed by ARJ Software Russia with the most
      of original ARJ code left intact. It has been briefly tested  on the
      following systems:

      DOS:

        MS-DOS v 2.11, 3.20, 3.21, 4.01, 5.00, 6.00, 6.20, 6.22
        PC DOS v 6.30, 7.00
        Windows 95, 98
        Windows NT Workstation v 3.51, 4.00

      OS/2:

        IBM OS/2 v 1.30, 2.00, 2.10, 3.00, 4.00, 4.50
        OS/2 subsystem in Windows NT Workstation v 3.51, 4.00.

      The following file systems have been chosen for testing:

        FAT, HPFS, Ext2FS and NTFS.


      The development team:

                      Programmed  by  Andrew Belov
                    Testing lead  by  Viatcheslav Odintsov

      Source code is not available for public use.


      End of document