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.

Howard Chu@JPL                                     11 Nov 1991                                            ARC(1)