1ARC(1)                          LOCAL COMMANDS                          ARC(1)
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NAME

6       arc - pc archive utility
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SYNOPSIS

9       arc a|m|u|f|d|x|e|r|p|l|v|t|c [ biswnoq ] [ gpassword ] archive [ file‐
10       name ...]
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DESCRIPTION

13       Arc is a general archive and file compression utility, used to maintain
14       a  compressed  archive of files.  An archive is a single file that com‐
15       bines many files, reducing storage space and allowing multiple files to
16       be  handled  as  one.   Arc uses one of several compression methods for
17       each file within the archive, based  on  whichever  method  yields  the
18       smallest result.
19

INSTRUCTIONS

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

24       a  add files to archive.  Copies the indicated files to the archive.
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26       m  move files to archive.  Same as 'a' switch except that the files are
27          deleted from the directory as they are moved to the archive.
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29       u  update files in archive.  This switch will  replace  archived  files
30          when the named file is newer than the archived copy.  New files will
31          be added automatically.
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33       f  freshen files in archive.  Same as 'u' except that  new  files  will
34          not be added.
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36       d  delete  files  in archive.  The named files are removed from the ar‐
37          chive.
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39       x,e
40          extract files from archive.  The named files are extracted from  the
41          archive  and  created  in  the  current directory in an uncompressed
42          state.
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44       r  run one file with arguments from archive.  Any program may  be  exe‐
45          cuted  directly  from  the  archive.  The parameters given after the
46          program name are passed to the program without modification.
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48       p  copy files from archive to standard output.  Useful with  I/O  redi‐
49          rection.  A  form-feed is appended after each file, to ease use with
50          printers.
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52       l  list files in archive.  Limited information listing  of  files  con‐
53          tained  in  an archive.  Displays the filename, original length, and
54          date last modified.  If the 'n' option (see below) is used, only the
55          filename is displayed.
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57       v  verbose  listing  of files in archive.  Complete information listing
58          of files contained in an archive.  Displays the  filename,  original
59          length, storage method, storage factor (% savings), compressed size,
60          date, time, and CRC.
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62       t  test archive integrity.  Computes CRC values for each member of  the
63          archive and compares against the previously saved value.
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65       c  convert  entry  to  new  packing  method.  Convert files stored with
66          older methods to newer methods that are more efficient. Also  useful
67          for files previously archived with the 's' option.
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OPTIONS

70       b  retain  backup  copy of archive.  Keep the original archive file and
71          rename to .BAK.  This switch may be used  with  the  following  com‐
72          mands:  a, m, u, f, d, c.
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74       i  suppress image mode.  This switch causes files to be treated as text
75          files, and will translate their end-of-line sequence.  (Unix's  '\n'
76          vs.  '\r\n'  used on many other systems.)  The default is to perform
77          no translation when compressing or extracting  files.   This  option
78          makes  dealing  with  text files much nicer, though the 'tr' command
79          can also be used. ('\r' in makefiles and C source  code  is  such  a
80          nuisance...)
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82       s  suppress  compression.   This  forces  new  files  to be saved using
83          Method 2 (no compression).  This switch may be used with the follow‐
84          ing commands:  a, m, u, f, c.
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86       w  suppress  warning  messages.  This switch will keep warning messages
87          from being displayed which is the default.   Most  warnings  concern
88          the deletion or existence of files with the same name.
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90       n  suppress  notes  and  comments.   This switch will keep useful notes
91          from being displayed which is the default.  Most notes indicate what
92          stage of compression is being run (analyze, compaction, storage).
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94       o  overwrite  existing  files  when  extracting.  This switch will make
95          existing files silently get overwritten, instead of asking for  con‐
96          firmation, which is the default.
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98       q  force Squash compression method.  This switch causes the Squash com‐
99          pression method to be used, instead of Crunch, which is the default.
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101       g  encrypt/decrypt archive entry.  This is used to encode files so that
102          others may not read them.  BE CAREFUL!  This must be the last param‐
103          eter in the switches because everything following  is  part  of  the
104          password.
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PROGRAMMING NOTES

107       Arc  Version 2 differs from version 1 in that archive entries are auto‐
108       matically compressed when they are added to the archive, making a sepa‐
109       rate  compression  step  unnecessary.  The nature of the compression is
110       indicated by the header version number placed in each archive entry, as
111       follows:
112                1 = Old style, no compression
113                2 = New style, no compression
114                3 = Compression of repeated characters only
115                4 = Compression of repeated characters plus Huffman SQueezing
116                5 = Lempel-Zev packing of repeated strings (old style)
117                6 = Lempel-Zev packing of repeated strings (new style)
118                7 = Lempel-Zev Williams packing with improved hash function
119                8 = Dynamic Lempel-Zev packing with adaptive reset
120                9 = Squashing
121
122       Type 5, Lempel-Zev packing, was added as of version 4.0
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124       Type  6  is  Lempel-Zev  packing where runs of repeated characters have
125       been collapsed, and was added as of version 4.1
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127       Type 7 is a variation of Lempel-Zev using  a  different  hash  function
128       which  yields speed improvements of 20-25%, and was added as of version
129       4.6
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131       Type 8 is a different implementation of Lempel-Zev,  using  a  variable
132       code size and an adaptive block reset, and was added as of version 5.0
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134       Type  9  is another variation of Lempel-Zev, using a larger hash table.
135       This method was developed by Phil Katz, and is  not  supported  by  the
136       "official" ARC programs.
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138       Arc will look for environment variables named ARCTEMP or TMPDIR, which,
139       if present, indicates the pathname where temporary files should be cre‐
140       ated.  This  is typically the location of a RAMdisk on a microcomputer,
141       "/tmp/" or left unset.
142
143       See the included documentation file for more details.
144

HISTORY

146       Arc has been in use in the CP/M and MSDOS world for many  years.   Thom
147       Henderson  developed  the original version, but it is important to note
148       that arc is based on the file compression theories developed  by  Huff‐
149       man,  Welch,  Knott, Knuth, and many other scientists. This implementa‐
150       tion is based on version 5.21 of the MSDOS program.
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BUGS

153       Arc behaves just like the PC version of the program; all  functions  of
154       the  "usage" display are working.  Full compatibility with PC ARC files
155       is maintained, the price for which is that arc doesn't like long  file‐
156       names,  and  can  only archive files with names of up to 12 characters.
157       It will *sometimes* do The Right Thing with them, but I suggest you put
158       long-winded filenames in a "shar" before arcing them.
159
160       There  shouldn't  be  any  problems, (hah!) but if you find any, please
161       send them to me at:
162
163            hyc@hanauma.jpl.nasa.gov
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165

AUTHORS

167       Original MSDOS program by Thom Henderson
168       COPYRIGHT(C) 1985-87  by  System  Enhancement  Associates;  ALL  RIGHTS
169       RESERVED
170
171       Original  Lempel-Zev  code derived from compress 4.0.  Modified to sup‐
172       port Squashing by Dan Lanciani (ddl@harvard.edu) Ported from  MSDOS  by
173       Howard  Chu,  with  help  from John Gilmore (hoptoad!gnu), James Turner
174       (daisy!turner) and others.
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178Howard Chu@JPL                    11 Nov 1991                           ARC(1)
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