Re: [sot] file times / file metadata

From	"Pascal J. Bourguignon" <pjb@informatimago.com>
Newsgroups	comp.lang.c
Subject	Re: [sot] file times / file metadata
Date	2017-11-22 01:44 +0100
Organization	Informatimago
Message-ID	<m2mv3fcfbu.fsf@informatimago.com> (permalink)
References	(3 earlier) <eae94c1a-9e49-409a-8cfa-3683ce05082a@googlegroups.com> <m23757e43g.fsf@informatimago.com> <9b5fe3ff-a704-4776-947c-d795fbc303ff@googlegroups.com> <m2y3mzclv0.fsf@informatimago.com> <009fcbb1-57f4-4835-836b-216066bcf329@googlegroups.com>

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fir <profesor.fir@gmail.com> writes:

> its interesting but if that would be true then nodify time in copying
> would be always bigger than creation and i talked my experiments
> showed id dont look like that (and that shows it just seems not be
> true)

You're right.  cp will indeed update the mtime so it reports the original
timestamp instead of that of the copied file.

mtime is user modifiable, but ctime is protected by the kernel (only
root could modify it).

But the point is that it doesn't matter.  Those are not semantic times
and should not taken as such.

For example, when you update a file, you have basically two ways to do
it:

1- Open the file in R/W mode, modify it, close it.

2- Open the file in R mode, create a new file in W mode, copy the data
   while modifying it on the fly.  Close both files. Rename the old file
   as a backup file, rename the new file as the old file.

There are good advantages of doing it the second way.  But obvious it
changes the ctime!

Semantically, for a successful update, both ways should be equivalent:
the date the document was created, and the date the document was
modified should be the same.  This won't be reflected in the time stamps
kept by the file system.

-- 
__Pascal J. Bourguignon
http://www.informatimago.com

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Thread

[sot] file times / file metadata fir <profesor.fir@gmail.com> - 2017-11-21 11:50 -0800
  Re: [sot] file times / file metadata "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-21 21:05 +0100
    Re: [sot] file times / file metadata Ian Collins <ian-news@hotmail.com> - 2017-11-22 09:15 +1300
    Re: [sot] file times / file metadata fir <profesor.fir@gmail.com> - 2017-11-21 12:23 -0800
      Re: [sot] file times / file metadata fir <profesor.fir@gmail.com> - 2017-11-21 12:42 -0800
        Re: [sot] file times / file metadata fir <profesor.fir@gmail.com> - 2017-11-21 13:01 -0800
        Re: [sot] file times / file metadata "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-21 22:04 +0100
          Re: [sot] file times / file metadata fir <profesor.fir@gmail.com> - 2017-11-21 13:17 -0800
          Re: [sot] file times / file metadata fir <profesor.fir@gmail.com> - 2017-11-21 13:22 -0800
            Re: [sot] file times / file metadata "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-21 23:23 +0100
              Re: [sot] file times / file metadata Ian Collins <ian-news@hotmail.com> - 2017-11-22 11:34 +1300
              Re: [sot] file times / file metadata Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-11-21 17:34 -0500
              Re: [sot] file times / file metadata fir <profesor.fir@gmail.com> - 2017-11-21 16:16 -0800
                Re: [sot] file times / file metadata "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-22 01:44 +0100
                Re: [sot] file times / file metadata Ian Collins <ian-news@hotmail.com> - 2017-11-22 14:10 +1300
                Re: [sot] file times / file metadata gordonb.eiy78@burditt.org (Gordon Burditt) - 2017-11-28 01:55 -0600
          Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-22 11:07 +0100
            Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-22 09:13 -0500
              Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-22 15:50 +0100
                Re: [sot] file times / file metadata jameskuyper@verizon.net - 2017-11-22 07:08 -0800
                Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-22 16:22 +0100
                Re: [sot] file times / file metadata bartc <bc@freeuk.com> - 2017-11-22 15:37 +0000
                Re: [sot] file times / file metadata bartc <bc@freeuk.com> - 2017-11-22 15:43 +0000
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-22 15:01 -0500
                Re: [sot] file times / file metadata Ian Collins <ian-news@hotmail.com> - 2017-11-23 17:52 +1300
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-23 14:12 -0500
                Re: [sot] file times / file metadata Ian Collins <ian-news@hotmail.com> - 2017-11-24 08:28 +1300
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-24 08:52 -0500
                Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-23 09:39 +0100
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-23 14:17 -0500
                Re: [sot] file times / file metadata cross@spitfire.i.gajendra.net (Dan Cross) - 2017-11-28 16:44 +0000
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-28 14:23 -0500
                Re: [sot] file times / file metadata cross@spitfire.i.gajendra.net (Dan Cross) - 2017-11-28 19:35 +0000
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-30 15:54 -0500
                Re: [sot] file times / file metadata cross@spitfire.i.gajendra.net (Dan Cross) - 2017-11-30 21:43 +0000
                Re: [sot] file times / file metadata scott@slp53.sl.home (Scott Lurndal) - 2017-11-28 19:42 +0000
                Re: [sot] file times / file metadata cross@spitfire.i.gajendra.net (Dan Cross) - 2017-11-28 20:13 +0000
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-30 15:57 -0500
                Re: [sot] file times / file metadata scott@slp53.sl.home (Scott Lurndal) - 2017-11-30 21:17 +0000
                Re: [sot] file times / file metadata jameskuyper@verizon.net - 2017-11-28 09:35 -0800
                Re: [sot] file times / file metadata Ian Collins <ian-news@hotmail.com> - 2017-11-29 08:24 +1300
                Re: [sot] file times / file metadata Ian Collins <ian-news@hotmail.com> - 2017-11-29 08:27 +1300
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-28 14:29 -0500
                Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-29 09:51 +0100
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-30 15:59 -0500
                Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-29 10:00 +0100
                Re: [sot] file times / file metadata "James R. Kuyper" <jameskuyper@verizon.net> - 2017-11-29 09:11 -0500
                Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-29 15:28 +0100
                Re: [sot] file times / file metadata "James R. Kuyper" <jameskuyper@verizon.net> - 2017-11-29 11:32 -0500
                Re: [sot] file times / file metadata James Kuyper <jameskuyper@verizon.net> - 2017-11-23 15:05 -0500
                Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-24 10:20 +0100
                Re: [sot] file times / file metadata Jerry Stuckle <jstucklex@attglobal.net> - 2017-11-24 09:05 -0500
                Re: [sot] file times / file metadata Robert Wessel <robertwessel2@yahoo.com> - 2017-11-24 22:50 -0600
                Re: [sot] file times / file metadata cross@spitfire.i.gajendra.net (Dan Cross) - 2017-11-28 16:59 +0000
                Re: [sot] file times / file metadata Ian Collins <ian-news@hotmail.com> - 2017-11-29 08:26 +1300
                Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-29 10:10 +0100
                Re: [sot] file times / file metadata cross@spitfire.i.gajendra.net (Dan Cross) - 2017-11-29 21:01 +0000
                Re: [sot] file times / file metadata David Brown <david.brown@hesbynett.no> - 2017-11-29 23:13 +0100
                Re: [sot] file times / file metadata cross@spitfire.i.gajendra.net (Dan Cross) - 2017-11-30 17:26 +0000
              Re: [sot] file times / file metadata fir <profesor.fir@gmail.com> - 2017-11-22 08:00 -0800
              Re: [sot] file times / file metadata "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-22 17:11 +0100
            Re: [sot] file times / file metadata "Pascal J. Bourguignon" <pjb@informatimago.com> - 2017-11-22 16:51 +0100
              Re: [sot] file times / file metadata scott@slp53.sl.home (Scott Lurndal) - 2017-11-22 16:36 +0000

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