1ARC(1) LOCAL COMMANDS ARC(1)
2
6 arc - pc archive utility
7
9 arc a|m|u|f|d|x|e|r|p|l|v|t|c [ biswnoq ] [ gpassword ] archive [ file‐
10 name ...]
11
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
21 Execute arc with no arguments for fairly verbose, usable instructions.
22
24 a add files to archive. Copies the indicated files to the archive.
25 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.
28 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.
32 f freshen files in archive. Same as 'u' except that new files will
34 not be added.
35 d delete files in archive. The named files are removed from the ar‐
37 chive.
38 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.
43 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.
47 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.
51 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.
56 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.
61 t test archive integrity. Computes CRC values for each member of the
63 archive and compares against the previously saved value.
64 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.
68
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.
73 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...)
81 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.
85 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.
89 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).
93 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.
97 q force Squash compression method. This switch causes the Squash com‐
99 pression method to be used, instead of Crunch, which is the default.
100 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.
105
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 Type 5, Lempel-Zev packing, was added as of version 4.0
123 Type 6 is Lempel-Zev packing where runs of repeated characters have
125 been collapsed, and was added as of version 4.1
126 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
130 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
133 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.
137 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 See the included documentation file for more details.
144
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.
151
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 There shouldn't be any problems, (hah!) but if you find any, please
161 send them to me at:
162 hyc@hanauma.jpl.nasa.gov
164
167 Original MSDOS program by Thom Henderson
168 COPYRIGHT(C) 1985-87 by System Enhancement Associates; ALL RIGHTS
169 RESERVED
170 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.
175Howard Chu@JPL 11 Nov 1991 ARC(1)