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MAN PAGE: ARC(1L)Contents
arc - pc archive utility
arc a|m|u|f|d|x|e|r|p|l|v|t|c [ biswnoq ] [ gpassword ]
archive [ filename ...]
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, reduc
ing storage space and allowing multiple files to be han
dled as one. Arc uses one of several compression methods
for each file within the archive, based on whichever
method yields the smallest result.
Execute arc with no arguments for fairly verbose, usable
instructions.
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 parame
ters 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 dis
played.
v verbose listing of files in archive. Complete informa
tion listing of files contained in an archive. Dis
plays 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 previ
ously 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.
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 transla
tion 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 warn
ing 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.
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 uneces
sary. 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 char
acters 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.
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.
Arc behaves just like the PC version of the program; all
functions of the "usage" display are working. Full com
patibility 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 sug
gest you put long-winded filenames in a "shar" before arc
ing them.
There shouldn't be any problems, (hah!) but if you find
any, please send them to me at:
hyc@hanauma.jpl.nasa.gov
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. Modi
fied to support Squashing by Dan Lanciani (ddl@har
vard.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 4 |
