A RAR and a PAR walk into a bar...

[Palomine]

 Regardless of platform/OS or choice of application, using multi-part RAR archives along with their PAR/PAR2 parity files to assemble and complete large files even when some parts of the file are incomplete on the server is a handy thing... one that I didn't bother to learn/figure out till perhaps just several years ago. Though I use MacPar Deluxe and am generally happy with it, there are cases when there's just too much missing from some segments for the parity files to make up for, and/or cases when the provided parity files are so scant/modest that they can't help repair even minor/small missing segments.

I point all of this obviousness out to mention something odd but sometimes useful: on occasion, when the unraring attempt fails due to insufficient pars, I have re-assembled the main file manually (using any basic tool such as Split & Concat or E Pluribus Unum) to reassemble the incomplete segments into a single (still incomplete) big file and THEN used the PAR2 parity file to successfully run an unrar (this time on the reassembled file, rather than the segments from which it  was made). I have no idea why this would work, but once in a while it does. I mention it just in case someone else here can use the hint... it doesn't work every time, but sometimes it does, albeit inexplicably, since the reassembled file is nothing more than the sum of its parts.

 

[ElmerFudd]

Good to know we have an "expert" on board!

Another question:

My antivirus can check zip files for infection (I believe it unzips them in a quarantine area), but I recall hearing that it can't check rar's.  This would make them risky to open, wouldn't it?

Oh, on a Windows machine.  As usual, this probably is not a concern on a Mac.

[Palomine]

Quote:
ElmerFudd said:
Good to know we have an "expert" on board!

Another question:

My antivirus can check zip files for infection (I believe it unzips them in a quarantine area), but I recall hearing that it can't check rar's.  This would make them risky to open, wouldn't it?

Oh, on a Windows machine.  As usual, this probably is not a concern on a Mac.

I'm hardly an expert on the subject... just wanted to share this little potentially-useful little tidbit that I've come to notice over time. As for your question (not having Windows I can't speak from virus experience but I can apply common sense) ...YES, once a file is unrared (either a single rar or a multipart archive) the resulting file would be 'live' ...usually in the same location as the archive file(s). If that file were infected, and if that could create a problem... then caution is warranted.

If I had this conundrum and used a virus-sensitive OS, I'd probably set up a separate partition (or better yet, a separate drive with its own OS install) where I DLd rars and other stuff. There, IF an infection did happen, it wouldn't affect the main/primary OS partition... but if the unrared file was clean, I could then use it or bring it over into the main area, or archive it or whatever.  

[Palomine]

Just a follow-up re: my search for a usable utility to repair multi-segment parity-protected file archives using PAR2 files in Linux (these are mostly from older archives DLd from newsgroups years ago... recently, I see files of 2-3GB segmented without any PAR files at all for some reason).

I never had much luck with Ark/Archive Manager for Linux when it came to using PAR2 files... they're fine for basic unarchiving, but I could never manage to get them to use the PAR2 files to fix missing data in incomplete file segments. Recently I added two other utilities (from the Ubuntu Software Center, though I assume they apply to other Linux distributions) called PyPar2 and GPar2. They both seem to work with PAR2 files (GPar2 also supposedly works with regular/older PAR files)... at least for the most part.

However: back on Mac, I'd depend on MacRAR to use PAR2 files to repair HJ-Split-style segments BEFORE they were re-combined (with Split and Concat). In Linux, I shockingly still haven't found something to deal with HJ-Split segments at all, let alone with PAR2 files also. Neither PyPar2 or GPar2 seem to be willing to use PAR2 to repair HJ-Split segments (i.e.: filename.wmv.001, etc...) ...it's almost as if they want the segments to be re-combined first and then apply the PAR2 files (which makes no sense to me based on long/past experience with MacRAR).

I know very few folks here use Ubuntu (which I still LOVE btw ) and fewer still are trying to reconstitute years-old newsgroup downloads (where/when HJ-Split and PAR2 archives were common), so I'm not really expecting any advice/help (though it's always welcome of course). I just thought I'd update this thread and share the info about PyPar2 and GPar2 since they do work to some extent and might be of interest to others.



Added later: I did manage to combine segmented files by using an alternate file manager called Krusader... I'm pretty sure it's just running the 'cat' Unix line command (cat is short for concatenate of course: a word I've loved ever since I first learned it in the early 1990s, which happens to be the last time I used Unix line commands on a daily basis ). So, using Krusader (or cat itself in a terminal window) and either GPar2 or PyPar2, is should theoretically be possible to do most of what MacRAR does in OSX, albeit not quite as smoothly.