Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!csd4.milw.wisc.edu!lll-winken!arisia!sgi!shinobu!odin!sgi.com!scotth From: scotth@sgi.com (Scott Henry) Newsgroups: comp.sys.amiga Subject: Re: Filesystem Links. Message-ID: Date: 30 Jun 89 08:20:23 GMT References: <18765@louie.udel.EDU> Sender: news@odin.SGI.COM Reply-To: scotth@sgi.com Organization: Silicon Graphics Inc, Mountain View, CA Lines: 39 In-reply-to: KENNEDAM%WWPS@dupont.com's message of 29 Jun 89 21:02:05 GMT K> Sender: mmdf@udel.EDU K> Warning!!! Ignorant question ahead... K> Would someone explain the difference (or similarity) between Unix links and K> VAX/VMS logicals? In VMS I can define a logical to point to a file on a system K> across decnet or on another disk and all I have to do is refer to it by the K> logical name. Are links the same/similar/completely different? K> Sorry if this isn't the appropriate place for this but it's the only usenet K> conference I get. VMS logical names are (as near as I can tell) EXACTLY the same as Amiga ASSIGN's (except for some of the open() funtionality). VMS can fake SOME of the functionality of file links by the use of logical names because the open("name") function first looks for a logical name "name" to open (IF it meets the syntactic requirements for a logical name) before it tries to open a file by that name. Because of the syntactic differences between logical names and files, this is not a fully general solution. On unix, a file link (either hard or soft) has exactly the same syntax as a file (because it IS a file), so there are no non-file-system restrictions on access. For both logical names and soft (or symbolic) links, there is a physical distinction between the file and its "alias", as they are distinguishable. They may also cross file-system boundaries. Hard links are exactly the same as the "original" file, and there is literally no way to tell the "original" from the link. Hard links may not cross file-system boundaries. I expect that AmigaDos links will be somewhere between hard and soft links, both in syntax and functionality. I figured out how to make hard links under OFS (V1.1), but I didn't implement it because I couldn't figure out how to keep the disk validator from complaining, and declaring the disk corrupt... I hope this clears up some of the fog... K> Thanks...Tony -- Scott Henry #include