Date: Thu, 30 May 2002 10:59:58 -0400 From: Paul Mather <paul@gromit.dlib.vt.edu> To: questions@FreeBSD.ORG Subject: Re: mv vs. tar [overlapping] Message-ID: <20020530145958.GA10665@gromit.dlib.vt.edu> In-Reply-To: <bulk.11034.20020530021408@hub.freebsd.org> References: <bulk.11034.20020530021408@hub.freebsd.org>
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On Wed, 29 May 2002 23:19:00 -0400 (EDT) Jason Hunt <jhunt@lynden.on.ca> wrote:
=> When 'mv'ing files between locations on the same physical disk, then
=> the only filesystem operation that is being performed is to update the
=> directory tree. An exception to this is when using 'mv' between different
=> physical disks or over NFS mount points, in which case the method for 'cp'
=> ends up being performed.
=>
=> Basically, 'mv' will be much faster in most scenarios. Refer to my other
=> e-mail from about an hour ago for when you might not want to use 'mv'.
=>
=> Once again, I am no expert. I'm probably wrong on a few points and/or
=> overlooked some things. I havn't gotten that far yet in reading "The
=> Design and Implementation of the 4.4BSD Operating System", which
=> is an excellent book if you want to learn what goes on behind the scenes.
=> :)
It's a great book. The source code for FreeBSD is rather informative
in these instances, too. A perusal of /usr/src/bin/mv/mv.c yields the
fact that rename(2) is used to mv within filesystems; "cp and rm" is
used for mv across devices and filesystems---just as you say.
Cheers,
Paul.
e-mail: paul@gromit.dlib.vt.edu
"Without music to decorate it, time is just a bunch of boring production
deadlines or dates by which bills must be paid."
--- Frank Vincent Zappa
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