dennis@rlgvax.UUCP (Dennis.Bednar) (11/13/87)
Pardon me, but can someone please tell me why "arc.exe" was
chosen for the "archive/compresser" program? Why don't
people prefer to use compress instead (for data compression,
but not for archiving)?
And where did ARC originate from?
--
FullName: Dennis Bednar
UUCP: {uunet|sundc}!rlgvax!dennis
USMail: CCI; 11490 Commerce Park Dr.; Reston VA 22091
Telephone: +1 703 648 3300jbs@eddie.MIT.EDU (Jeff Siegal) (11/13/87)
In article <696@rlgvax.UUCP> dennis@rlgvax.UUCP (Dennis.Bednar) writes: > >Pardon me, but can someone please tell me why "arc.exe" was >chosen for the "archive/compresser" program? Why don't >people prefer to use compress instead (for data compression, >but not for archiving)? ARC is actually better than a simple compression program because it tries several compression schemes and uses the one which results in the smallest file (sometimes this is the original file!). Jeff Siegal
farren@gethen.UUCP (Michael J. Farren) (11/15/87)
In article <7406@eddie.MIT.EDU> jbs@eddie.MIT.EDU (Jeff Siegal) writes: >ARC is actually better than a simple compression program because it >tries several compression schemes and uses the one which results in >the smallest file (sometimes this is the original file!). While it is true that ARC chooses the 'best' compression method, this is somewhat of a red herring. The Unix 'compress' utility, using 16-bit Lempel-Zev compression, significantly outperforms ARC's 12-bit (or PKARC's 13-bit) compression on anything other than very small files, where the gain isn't significant, anyway. The only thing that ARC offers that compress does not is the ability to pack several files into one large file, which is a matter mostly of convenience, not of efficiency. BTW - the 'compress' utility is available for MS-DOS. I use it as often as I do ARC. -- ---------------- Michael J. Farren "... if the church put in half the time on covetousness unisoft!gethen!farren that it does on lust, this would be a better world ..." gethen!farren@lll-winken.arpa Garrison Keillor, "Lake Wobegon Days"
davidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr) (11/17/87)
I suspect that the best compression available with file extraction still
allowed is from a combination of compress and cpio. Here is how it's
done. Note that this is available to any system which has cpio (or afio)
and compress.
zoo: zoo a testit *.c
arc: arc a testit *.c
c+c: ls *.c | cpio -oc | compress > testit.CC
Extract single file
zoo: zoo x testit file.c
arc: arc x testit *.c
c+c: zcat <testit.CC | cpio -icm file.c
List an archive:
zoo: zoo v testit (or l or lf)
arc: arc v testit (or l)
c+c: zcat <testit.cc | cpio -octv (or oct)
Performance:
I tried this on a bunch of files which consisted of C source and
compiled files, I got these results (total input 34365 bytes):
CPU (u+s) file size
arc: 80.34 25736
zoo: 16.30 26282
c+c: 8.40 20511
The compression of the c+c method improves as the archive file gets
larger, while the others improve as the size of individual files gets
larger, until the 13 bit limit is reached.
I still use zoo for reasons I have mentioned before. It has a convenient
if baroque user interface, and is available for many systems including
VMS. Although I have cpio and compress for MS-DOS, I prefer zoo.
--
bill davidsen (wedu@ge-crd.arpa)
{uunet | philabs | seismo}!steinmetz!crdos1!davidsen
"Stupidity, like virtue, is its own reward" -mepozar@hoptoad.uucp (Tim Pozar) (11/17/87)
In article <7406@eddie.MIT.EDU> jbs@eddie.MIT.EDU (Jeff Siegal) writes: >In article <696@rlgvax.UUCP> dennis@rlgvax.UUCP (Dennis.Bednar) writes: >> >>Pardon me, but can someone please tell me why "arc.exe" was >>chosen for the "archive/compresser" program? Why don't >>people prefer to use compress instead (for data compression, >>but not for archiving)? > >ARC is actually better than a simple compression program because it >tries several compression schemes and uses the one which results in >the smallest file (sometimes this is the original file!). > >Jeff Siegal It also is the defacto standard (although pkarc is taking hold) for file compression and archiving for the ms-dos world. Where I use it the most is in the process of shipping files back and forth from unixland to msdosland. It speeds things up quite a bit. -- ======================================================================= | ...sun!hoptoad!\ Tim Pozar | | >fidogate!pozar Fido: 1:125/406 | | ...lll-winken!/ PaBell: (415) 788-3904 | | USNail: KKSF 77 Maiden Lane San Francisco CA 94108 | =======================================================================
w8sdz@brl-smoke.UUCP (11/19/87)
ARC offers internal error checking on each and every member file.
Compress does NO error checking. Try truncating a compressed file and
then uncompress it. There will be no complaints from the program.
--
Keith Petersen
Arpa: W8SDZ@SIMTEL20.ARPA
Uucp: {bellcore,decwrl,harvard,lll-crg,ucbvax,uw-beaver}!simtel20.arpa!w8sdz
GEnie: W8SDZdavidsen@steinmetz.steinmetz.UUCP (William E. Davidsen Jr) (11/24/87)
In article <6695@brl-smoke.ARPA> w8sdz@brl.arpa (Keith B. Petersen (WSMR|towson) <w8sdz>) writes: >ARC offers internal error checking on each and every member file. >Compress does NO error checking. Try truncating a compressed file and >then uncompress it. There will be no complaints from the program. The "zoo" archiver allows extraction of files from a damaged archive. This allows recovery of most of the info from a munged archive. -- bill davidsen (wedu@ge-crd.arpa) {uunet | philabs | seismo}!steinmetz!crdos1!davidsen "Stupidity, like virtue, is its own reward" -me