Date: Wed, 5 Aug 1998 11:33:24 -0700 (PDT) From: David Wolfskill <dhw@whistle.com> To: freebsd-questions@FreeBSD.ORG, gary@tein.net, romank@graphnet.com Subject: Re: Simple UNIX question Message-ID: <199808051833.LAA18242@pau-amma.whistle.com> In-Reply-To: <35C8916C.B87B5809@graphnet.com>
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>Date: Wed, 05 Aug 1998 13:07:56 -0400 >From: Roman Katsnelson <romank@graphnet.com> >a hard link will physically copy the file to be linked to to the >other location.... Either I'm misunderstanding the above, or it's not correct. Therefore, in order to try to help prevent misunderstanding: A "hard" link (originally, the only kind of link) creates another name by which a file may be known (a pathname). The new name, as well as any other names, actually are all equivalent to one another. (Originally, they all referred to the same inode; in turn, the inode specified where the file's data blocks happened to be, as well as the timestamps, permissions, ownership -- basically, all the neat stuff that stat() will tell you if you ask it nicely. This is still essentially the case, though tere are now lots of different kinds of filesystems, and directory entries now may refer to inodes or vnodes or.... But the point is that a "hard" link creates a directory entry, which refers to the place where the filesystem tracks the attributes of the file, so all such names are equivalent.) A "soft" (or "symbolic" -- thus "symlink") link creates a (textual) pointer to a pathname... which might be a name for a file, or could be another symlink (but be careful about overdoing that one!). One of the significant issues between the two is that a "hard" link can only refer to a file on the same filesystem. A symlink, however, can refer to a file on a different filesystem... or even a file on a different machine (given a suitable environment, such as one that does arguably interesting things with "amd"). david -- David Wolfskill UNIX System Administrator dhw@whistle.com voice: (650) 577-7158 pager: (650) 371-4621 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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