Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!olivea!decwrl!pa.dec.com!granite.pa.dec.com!mwm From: mwm@fenris.relay.pa.dec.com (Mike (My Watch Has Windows) Meyer) Newsgroups: comp.sys.amiga Subject: Re: Backup links on 2.0 Message-ID: Date: 6 Jan 91 05:45:24 GMT References: <40262@nigel.ee.udel.edu> <9999@pasteur.Berkeley.EDU> Sender: news@pa.dec.com (News) Organization: Missionaria Phonibalonica Lines: 54 In-Reply-To: navas@cory.Berkeley.EDU's message of 2 Jan 91 20:31:32 GMT In article <9999@pasteur.Berkeley.EDU> navas@cory.Berkeley.EDU (David C. Navas) writes: In article <40262@nigel.ee.udel.edu> boily@phy.ulaval.ca (Edouard Boily) writes: > Let's suppose you're in a directory, say "ram:t". If you make >a link with the following command "makelink .. /", it will be >impossible to backup the link directory you've just made. All the Ack, be quiet or we'll never get hardlinks :) :) No, keep talking, so that when we do get hard links, they don't introduce serious problems (like the one you've found). > Typically, the backup utilities mentioned get in an infifite >loop when they encountered those links. The author of ExpressCopy claims that 1.5 "correctly" handles links. I haven't verified it yet (I'm still trying to read the incredibly tiny type in the update docs), but given the quality of the program, I believe him. Right, that's because... > Another thing, why are those links showed as simple >directories and not as what they really are. When I do a list >command, I should not see > .. Dir ----rwed Today 23:23:17 >but I should see > .. --> Ram Disk: Link l---rwed Today 23:23:17 ...the links need to be invisible outside of the (filing?) system, so that they don't break every program written. Can you imagine what might happen to programs that only expected dirs or files to be getting garbage (links) instead -- insidious! Yes, but - any program that asks what _type_ a file is should be told "link" for soft links (I leave it as an exercise to decide why this isn't the case for hard links). Programs that blow up when given unexpected file types are broken. List qualifies as one such program. Howver, I'd rather have the pointer on the far end of the line. That's an overview of what *might* be happening -- anyone know for sure? [I'll probably read the docs tonight out of curiosity anyway...] You've basically got it right - though your philosophy is wrong. As far as I know, there's no documented way to tell if a file is a link or not (the preceeding statement is an open invitation to flame me in public, just so long as you _tell me_ that documented by CBM method!). The author of ExpressCopy poked around inside the file system to find a heuristic that worked. This may fail in the future, but is better than never working now.