arc

ARC(1L)                         LOCAL COMMANDS                         ARC(1L)



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 unecessary.  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; ALL RIGHTS
       RESERVED

       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(1L)