Path: utzoo!hoptoad!mejac!decwrl!labrea!eos!ames!nrl-cmf!mailrus!umix!hyc From: hyc@umix.cc.umich.edu (Howard Chu) Newsgroups: alt.sources Subject: ARC 5.20 w/Squashing, 2/9 Message-ID: <3997@umix.cc.umich.edu> Date: 14 Apr 88 05:57:04 GMT Reply-To: hyc@umix.cc.umich.edu (Howard Chu) Distribution: alt Organization: University of Michigan Computing Center, Ann Arbor Lines: 1000 UUCP-Path: {uunet,rutgers}!umix!hyc XX For example, if you just received an archive named XX"JUNK.ARC" over a phone line, and you want to make XXsure that you received it properly, you could type: XX XX ARC t junk XX XXIt defeats the purpose of the T command to combine it XXwith N or W. XX XX XX XX_____________________ XX XXThe "C" (Convert) command is used to convert an XXarchive entry to take advantage of newer compression XXtechniques. This is occasionally desirable when a new XXversion of ARC is released. Please refer to the XXrevision history section for details on when new XXcompression methods were implemented. XX XXFor example, if you had an archive named "JUNK.ARC", XXand you wanted to make sure that all files with an XXextension of ".DOC" were encoded using the very latest XXmethods, you could type: XX XX ARC c junk *.doc XX XXOr if you wanted to convert every file in the archive, XXyou could type: XX XX ARC c junk XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXARC Page 12 XX ARC OPTIONS XX XX XX XXThis section describes the options which are available XXto modify how ARC works. Any of these options can be XXcombined with any of the commands, though the result XXmay not always be something you'd want to do. XX XX XX XX_______________________ XX XXThe "S" (Suppress compression) option can be combined XXwith any command that updates archive entries. These XXinclude Add, Move, Update, Freshen, and Convert. The XXeffect of the S option is to prevent any compression XXtechniques from being employed. This is intended to XXallow you to add a few files at a time to an archive XXquickly, and then later convert the archive to XXcompress everything at once. XX XXFor example, over the course of a day you might give XXeach of the following commands: XX XX ARC as junk *.txt XX ARC as junk *.mac XX ARC as junk *.doc XX XXAt the end of the day, when you have finished adding XXthings to the archive, you could have all of the XXarchive entries compressed at once by typing: XX XX ARC c junk XX XXYou could also decompress the archive by typing: XX XX ARC cs junk XX XXthough I can't imagine why you'd want to. XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXARC Page 13 XX ________________ XX XXWhen ARC changes an archive (during an Add, Move, XXUpdate, Freshen, Delete, or Convert) it creates a new XXarchive with the same name, but with an extension of XX".$$$". For example, if you add a file to an archive XXnamed STUFF.ARC, then ARC will create a new archive XXnamed STUFF.$$$. ARC will read from your existing XXarchive and write out the new archive with any changes XXto the ".$$$" copy. XX XXNormally when ARC is finished it deletes the original XXand renames the new archive to the original name (ie. XXSTUFF.ARC goes away, and STUFF.$$$ becomes the new XXSTUFF.ARC). Among other things, this means that if XXanything goes wrong and ARC is unable to finish, then XXyour original archive will still be intact. XX XX XXIn some circumstances you may wish to retain the XXoriginal version of the archive as a backup copy. You XXcan do this easily by using the Backup option. Add XXthe letter "B" to your command, and ARC will rename XXyour original archive to have an extension of ".BAK" XXinstead of deleting it. XX XX XXIn other words, if you wanted to add "WASTE.TXT" to an XXarchive named "JUNK.ARC", but wanted to keep a backup XXcopy, then you would type: XX XX ARC ab junk waste.txt XX XXYour original archive would become "JUNK.BAK", while XX"JUNK.ARC" would contain the new "WASTE.TXT" file. XX XX XXIf you keep a backup of an archive which already has a XXbackup, then the older backup copy is deleted. XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXARC Page 14 XX ___________________ XX XXARC prints three types of messages: warnings, XXcomments, and errors. XX XXWarnings are messages about suspected error XXconditions, such as when a file to be extracted XXalready exists, or when an extracted file fails the XXCRC error check. Warnings may be suppressed by use of XXthe "W" (Warn) command. You should use this command XXsparingly. In fact, you should probably not use this XXcommand at all. XX XXComments (or notes) are informative messages, such as XXnaming each file as it is added to the archive. XXComments and notes may be suppressed by use of the "N" XX(Note) command. XX XXErrors are actual system problems, such as running out XXof disk space. You cannot suppress errors. XX XX XXFor example, suppose you extracted all files with an XXextension of ".BAS" from an archive named "JUNK.ARC" XXThen, after making some changes which you decide not XXto keep, you decide that you want to extract them all XXagain, but you don't want to be asked to confirm every XXone. In this case, you could type: XX XX ARC xw junk *.bas XX XXOr, if you are going to add a hundred files with an XXextension of ".MSG" to an archive named "TRASH.ARC", XXand you don't want ARC to list them as it adds them, XXyou could type: XX XX ARC an trash *.msg XX XXOr, if you want to extract the entire contents of an XXarchive named "JUNK.ARC", and you don't want to hear XXanything, then type: XX XX ARC xnw junk XX XX XXA special case is provided when extracting files from XXan archive. One of the various warnings that can XXoccur is when a file being extracted already exists on XXdisk. Normally, ARC will stop and ask you if you want XXto overwrite the file. This can be suppressed with XXthe "W" command, but that will also suppress any XX XX XX XXARC Page 15 XX warnings about other things, like failed CRC checks XXand such. XX XX ____ XXthat the file already exists. For example, in our XXearlier case of extracting all the ".BAS" files from XX"JUNK.ARC", a much safer way to do it is to type: XX XX ARC xo junk *.BAS XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXARC Page 16 XX _____________________ XX XXArchive entries may be encrypted and decrypted by XXusing the "G" (Garble) option. The Garble option XXtakes the remainder of the command string as the XX ____ XX XX XXFor example, if you wanted to add a file named XX"WASTE.TXT" to an archive named "JUNK.ARC", and you XXwanted to encrypt it using the password "DEBRIS", then XXyou would type: XX XX ARC agdebris junk waste.txt XX XXLater on, when you want to extract it again, you would XXtype: XX XX ARC xgdebris junk waste.txt XX XXThe password you supply is used to encrypt (or XXdecrypt) the archive entry by performing an exclusive XXOR between each byte of the packed data and each byte XXof the password. The password can be any length, and XXeach of its bytes is used in rotation. The password XXis converted to uppercase before it is used, so it is XX___ XXon the packed data, it has no effect on stowage XXfactors. XX XXThis is not a particularly sophisticated means of XXencryption, and it is theoretically possible to crack. XXStill, since it is performed on the packed data, the XXresult should be quite sufficient for casual use. XX XX XXYou can, if you wish, use different passwords for XXdifferent files in an archive, but we advise against XXit. If you are going to encrypt an archive, we XXsuggest you use the same password for every file, and XXgive the password whenever you do anything at all with XXthe archive. It is possible to list the entries in an XXencrypted archive using the "L" and "V" commands XXwithout giving the password, but nothing else will XXwork properly. XX XX XXWe advise that you use this option sparingly, if at XXall. If you should forget or mistype your password, XXit is highly unlikely that you will ever recover your XXdata. XX XX XX XXARC Page 17 XX RAMDISK SUPPORT XX XX XX XXIf you have a RAMdisk, or other high-speed storage, XXthen you can speed up ARC somewhat by telling it to XXput its temporary files on the RAMdisk. You do this XXby setting the ARCTEMP environment string with the MS- XXDOS SET command. For example, if drive B: is your XXRAMdisk, then you would type: XX XX set ARCTEMP=B: XX XXRefer to the MS-DOS manual for more details about the XXSET command. You need only set the ARCTEMP string XXonce, and ARC will use it from then on until you XXchange its value or reboot your system. XX XX XXIf ARC does not find an environment string named XXARCTEMP, then it looks for one named TEMP to use XXinstead. Several packages already use the TEMP string XXfor exactly this purpose. If you have need of an XXenvironment string named TEMP for something else, then XXyou should be sure to define ARCTEMP. XX XX XXThere are a limited number of temporary files created XXby ARC. The Convert command uses a file named XX"$ARCTEMP.CVT" to hold each file as it is being XXconverted. The Run command also creates a temporary XXfile, which has the name "$ARCTEMP", and whose XXextension matches that of the file being run. XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XXARC Page 18 XX MARC XX XX XX XXMARC is a separate program which is used to merge XXarchives created by ARC. MARC moves files from one XXarchive to another without unpacking them. XX XX XXMARC is used as follows: XX XX MARC [