Path: ...!eternal-september.org!feeder2.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: <bp@www.zefox.net>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Are files overwritten in place by sftp?
Date: Sun, 17 Nov 2024 23:35:56 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 34
Message-ID: <vhduks$shdk$1@dont-email.me>
References: <vhd948$nate$2@dont-email.me> <vhdhf3$ptqv$1@dont-email.me>
Injection-Date: Mon, 18 Nov 2024 00:35:56 +0100 (CET)
Injection-Info: dont-email.me; posting-host="94efef249b9f74a309097f7c8e620c2a";
	logging-data="935348"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+GBmwHd8uUlQx/pcD9gLsotr66UimtNgE="
User-Agent: tin/2.6.2-20221225 ("Pittyvaich") (FreeBSD/14.1-RELEASE-p5 (arm64))
Cancel-Lock: sha1:R3+c47O4WwBOTapBnF93icQoOcA=
Bytes: 2270

Steven G. Kargl <sgk@removetroutmask.apl.washington.edu> wrote:
> On Sun, 17 Nov 2024 17:28:40 +0000, bp wrote:
> 
>> In the event one copies a file or directory over an existing
>> file or directory is the duplicate written to the same physical
>> blocks in storage, or are new physical blocks written with the 
>> old blocks marked free? 
>> 
>> The situation in mind is using get -r to copy a remote directory,
>> then changing or adding a few files to the remote directory followed
>> by using get -r to get the directory a second time. Clearly, changed
>> files will require writing new blocks on the destination, but what
>> about files with unchanged paths and contents?
>> 
>> The question is motivated by concerns about limited-life storage 
>> media such as flash.
> 
> From the description, it seems that you are looking for
> the net/rsync port.  The first time it is executed, it
> will copy the directory.  Additional invocations of rsync
> will only copy modified files.  rsync also allows you
> to exclude files from being copied such as *.o which can
> change quite often.
> 

Your surmise is correct, but I wanted to use sftp out of familiarity.
I'm compiling net/rsync now to have a look at it, but I'm still
curious how file overwrites, whether across the net or locally, are
handled.  

Thanks for writing!

bob prohaska