While working out a strategy for DVD backups on my server I found some handy tools for working with ISO files. I used some of these to prevent wasting media on test burns (sure, re-writable media would be good, but why not live on the edge and toast all of your WORM media?).
This is the one that saved me from wasting (a lot of) media so I’ll start with it. Since I need to create DVDs that can be read both in Windows and Linux I create my media utilizing both the MS Joliet specification and Rock Ridge standard. Basically, both of these extensions to the ISO9660 standard allow for additional file information to be stored on CD/DVD (long filenames, permissions and so on).
Initially I was attempting to create an ISO containing files with names exceeding 64 characters. Joliet technically only allows for 64 and was doing awful things to my file names (umm hello, truncating the extension?). Isoinfo (
-lJ) allowed me to see that the Joliet filenames were broken. Had I burned that DVD it would have appeared fine on my Linux machines (as they would be referring the RR data on the DVD) but would have been been a problem on my Windows boxes. Just that command saved me at least two discs
isoinfo -i <iso> -lJ: View info from Joliet extensions
isoinfo -i <iso> -lR: View info from RR extensions
isoinfo -i <iso> -d: View ISO’s properties
Isovfy’s man page states: isovfy is a utility to verify the integrity of an iso9660 image. Most of the tests in isovfy were added after bugs were discovered in early versions of genisoimage. It isn’t all that clear how useful this is anymore, but it doesn’t hurt to have this around.
Lack luster description, I personally don’t know how useful it is either but I figure that if you download an ISO, it couldn’t hurt to run this proggie on it for a quick sanity check.
Yeah, this one is a mystery to me. I personally couldn’t find a human use for this one at all. isodump is a crude utility to interactively display the contents of iso9660 images in order to verify directory integrity. The initial screen is a display of the first part of the root directory, and the prompt shows you the extent number and offset in the extent.
Feel free to try it on your ISO, just keep in mind that the man page is accurate, it’s crude. Personally, I get what I need from the other two utils so I’ll just forget about this one.
That’s all I have on ISOs for now, check out the wikipedia links throughout the post, if you’re a little geeky it’s interesting reading