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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 [ file-
       name ...]

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 com-
       bines 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 ar-
	  chive.

       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  exe-
	  cuted	 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	 redi-
	  rection.  A  form-feed is appended after each	file, to ease use with
	  printers.

       l  list files in	archive.  Limited information listing  of  files  con-
	  tained  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  com-
	  mands:  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 follow-
	  ing 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 ex-
	  isting files silently	get overwritten, instead of asking for confir-
	  mation, which	is the default.

       q  force	Squash compression method.  This switch	causes the Squash com-
	  pression 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	param-
	  eter 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 auto-
       matically compressed when they are added	to the archive,	making a sepa-
       rate compression	step unecessary.  The nature of	the compression	is in-
       dicated 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 cre-
       ated.  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	 Huff-
       man,  Welch,  Knott, Knuth, and many other scientists. This implementa-
       tion 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	 file-
       names,  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  RE-
       SERVED

       Original	 Lempel-Zev  code derived from compress	4.0.  Modified to sup-
       port 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)

NAME | SYNOPSIS | DESCRIPTION | INSTRUCTIONS | COMMAND SWITCHES | OPTIONS | PROGRAMMING NOTES | HISTORY | BUGS | AUTHORS

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