NAME

       arc - pc archive utility

SYNOPSIS

       arc a|m|u|f|d|x|e|r|p|l|v|t|c [ biswnoq ] [ gpassword ] archive [ filename ...]

DESCRIPTION

       Arc  is  a  general  archive  and  file compression utility, used to maintain a compressed
       archive of files.  An archive is a single file that combines many files, reducing  storage
       space  and  allowing  multiple  files  to  be  handled  as  one.   Arc uses one of several
       compression methods for each file within the archive, based on whichever method yields the
       smallest result.

INSTRUCTIONS

       Execute arc with no arguments for fairly verbose, usable instructions.

COMMAND SWITCHES

       a  add files to archive.  Copies the indicated files to the archive.

       m  move  files  to archive.  Same as 'a' switch except that the files are deleted from the
          directory as they are moved to the archive.

       u  update files in archive.  This switch will replace archived files when the  named  file
          is newer than the archived copy.  New files will be added automatically.

       f  freshen files in archive.  Same as 'u' except that new files will not be added.

       d  delete files in archive.  The named files are removed from the archive.

       x,e
          extract files from archive.  The named files are extracted from the archive and created
          in the current directory in an uncompressed state.

       r  run one file with arguments from archive.  Any program may be  executed  directly  from
          the  archive.   The  parameters  given after the program name are passed to the program
          without modification.

       p  copy files from archive to standard output.  Useful with I/O redirection.  A  form-feed
          is appended after each file, to ease use with printers.

       l  list  files  in archive.  Limited information listing of files contained in an archive.
          Displays the filename, original length, and date last modified.  If the 'n' option (see
          below) is used, only the filename is displayed.

       v  verbose  listing  of files in archive.  Complete information listing of files contained
          in an archive.  Displays the filename, original length, storage method, storage  factor
          (% savings), compressed size, date, time, and CRC.

       t  test  archive  integrity.   Computes  CRC  values  for  each  member of the archive and
          compares against the previously saved value.

       c  convert entry to new packing method.  Convert files stored with older methods to  newer
          methods that are more efficient. Also useful for files previously archived with the 's'
          option.

OPTIONS

       b  retain backup copy of archive.  Keep the original archive  file  and  rename  to  .BAK.
          This switch may be used with the following commands:  a, m, u, f, d, c.

       i  suppress  image  mode.   This switch causes files to be treated as text files, and will
          translate their end-of-line sequence. (Unix's  '\n'  vs.  '\r\n'  used  on  many  other
          systems.)   The  default  is  to  perform no translation when compressing or extracting
          files.  This option makes dealing with text files much nicer, though the  'tr'  command
          can also be used. ('\r' in makefiles and C source code is such a nuisance...)

       s  suppress  compression.   This  forces  new  files  to  be  saved  using  Method  2  (no
          compression).  This switch may be used with the following commands:  a, m, u, f, c.

       w  suppress warning messages.  This switch will keep warning messages from being displayed
          which  is  the  default.  Most warnings concern the deletion or existence of files with
          the same name.

       n  suppress notes and comments.  This switch will keep useful notes from  being  displayed
          which  is  the  default.   Most  notes  indicate what stage of compression is being run
          (analyze, compaction, storage).

       o  overwrite existing files  when  extracting.   This  switch  will  make  existing  files
          silently get overwritten, instead of asking for confirmation, which is the default.

       q  force  Squash  compression method.  This switch causes the Squash compression method to
          be used, instead of Crunch, which is the default.

       g  encrypt/decrypt archive entry.  This is used to encode files so  that  others  may  not
          read  them.   BE  CAREFUL!   This  must  be  the last parameter in the switches because
          everything following is part of the password.

PROGRAMMING NOTES

       Arc Version 2 differs from version 1 in that archive entries are automatically  compressed
       when  they  are added to the archive, making a separate compression step unnecessary.  The
       nature of the compression is indicated by the header version number placed in each archive
       entry, as follows:
                1 = Old style, no compression
                2 = New style, no compression
                3 = Compression of repeated characters only
                4 = Compression of repeated characters plus Huffman SQueezing
                5 = Lempel-Zev packing of repeated strings (old style)
                6 = Lempel-Zev packing of repeated strings (new style)
                7 = Lempel-Zev Williams packing with improved hash function
                8 = Dynamic Lempel-Zev packing with adaptive reset
                9 = Squashing

       Type 5, Lempel-Zev packing, was added as of version 4.0

       Type  6  is  Lempel-Zev packing where runs of repeated characters have been collapsed, and
       was added as of version 4.1

       Type 7 is a variation of Lempel-Zev using a different hash  function  which  yields  speed
       improvements of 20-25%, and was added as of version 4.6

       Type  8  is  a  different  implementation of Lempel-Zev, using a variable code size and an
       adaptive block reset, and was added as of version 5.0

       Type 9 is another variation of Lempel-Zev, using a larger  hash  table.  This  method  was
       developed by Phil Katz, and is not supported by the "official" ARC programs.

       Arc  will  look  for  environment  variables  named  ARCTEMP or TMPDIR, which, if present,
       indicates the pathname where temporary files should be  created.  This  is  typically  the
       location of a RAMdisk on a microcomputer, "/tmp/" or left unset.

       See the included documentation file for more details.

HISTORY

       Arc  has been in use in the CP/M and MSDOS world for many years.  Thom Henderson developed
       the original version, but it  is  important  to  note  that  arc  is  based  on  the  file
       compression theories developed by Huffman, Welch, Knott, Knuth, and many other scientists.
       This implementation is based on version 5.21 of the MSDOS program.

BUGS

       Arc behaves just like the PC version of the program; all functions of the "usage"  display
       are  working.   Full compatibility with PC ARC files is maintained, the price for which is
       that arc doesn't like long filenames, and can only archive files with names of  up  to  12
       characters.  It will *sometimes* do The Right Thing with them, but I suggest you put long-
       winded filenames in a "shar" before arcing them.

       There shouldn't be any problems, (hah!) but if you find any, please send them to me at:

            hyc@hanauma.jpl.nasa.gov

AUTHORS

       Original MSDOS program by Thom Henderson
       COPYRIGHT(C) 1985-87 by System Enhancement Associates.  You may copy and  distribute  this
       program freely, under the terms of the General Public License.

       Original  Lempel-Zev code derived from compress 4.0.  Modified to support Squashing by Dan
       Lanciani (ddl@harvard.edu) Ported from MSDOS by Howard Chu, with help  from  John  Gilmore
       (hoptoad!gnu), James Turner (daisy!turner) and others.