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.