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Creation of empty files [was: Useful use of dd]

From David Christensen <dpchrist@holgerdanske.com>
Newsgroups linux.debian.user
Subject Creation of empty files [was: Useful use of dd]
Date 2021-07-02 23:40 +0200
Message-ID <Cwz3b-135-1@gated-at.bofh.it> (permalink)
References (3 earlier) <CwilH-7y5-1@gated-at.bofh.it> <CwkdP-rs-3@gated-at.bofh.it> <Cwm5X-1xu-5@gated-at.bofh.it> <CwoAN-3dZ-3@gated-at.bofh.it> <CwwI2-8fr-3@gated-at.bofh.it>
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On 7/2/21 11:51 AM, Kushal Kumaran wrote:
> On Fri, Jul 02 2021 at 01:26:23 PM, Teemu Likonen <tlikonen@iki.fi> wrote:

>> For this new subject I will add another use: quickly create empty file
>> of specific size, for example 5 * 1024 bytes:
>>
>>      $ dd of=empty obs=1024 seek=5 count=0


2021-07-02 14:20:47 dpchrist@dipsy ~/sandbox/dd
$ dd of=dd-sparse bs=1M seek=5 count=0
0+0 records in
0+0 records out
0 bytes copied, 6.9482e-05 s, 0.0 kB/s

2021-07-02 14:21:16 dpchrist@dipsy ~/sandbox/dd
$ ll dd-sparse
-rw-r--r-- 1 dpchrist dpchrist 5242880 2021-07-02 14:21:16 dd-sparse

2021-07-02 14:21:40 dpchrist@dipsy ~/sandbox/dd
$ du --bytes dd-sparse
5242880	dd-sparse


> There's
> 
>      $ truncate --size 5k testfile
> 
> for this purpose.


2021-07-02 14:23:34 dpchrist@dipsy ~/sandbox/dd
$ time truncate --size 5M truncate-sparse

real	0m0.002s
user	0m0.002s
sys	0m0.001s

2021-07-02 14:24:25 dpchrist@dipsy ~/sandbox/dd
$ ll truncate-sparse
-rw-r--r-- 1 dpchrist dpchrist 5242880 2021-07-02 14:24:25 truncate-sparse

2021-07-02 14:24:30 dpchrist@dipsy ~/sandbox/dd
$ du --bytes truncate-sparse
5242880	truncate-sparse


I expected sparse files, but du(1) does not indicate such (?).


Comments?


David

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Thread

Whole Disk Encryption + SSD piorunz <piorunz@gmx.com> - 2021-06-28 17:00 +0200
  Re: Whole Disk Encryption + SSD Jochen Spieker <ml@well-adjusted.de> - 2021-06-28 18:00 +0200
  Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-06-28 22:40 +0200
    Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-06-29 00:00 +0200
    Re: Whole Disk Encryption + SSD Stefan Monnier <monnier@iro.umontreal.ca> - 2021-06-29 02:00 +0200
      Re: Whole Disk Encryption + SSD <tomas@tuxteam.de> - 2021-06-29 09:50 +0200
        Re: Whole Disk Encryption + SSD Stefan Monnier <monnier@iro.umontreal.ca> - 2021-06-30 00:50 +0200
        Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-06-30 01:00 +0200
    Re: Whole Disk Encryption + SSD Jonathan Dowland <jon+debian-user@dow.land> - 2021-06-29 11:30 +0200
    Re: Whole Disk Encryption + SSD piorunz <piorunz@gmx.com> - 2021-06-29 14:10 +0200
      Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-06-30 02:20 +0200
    Re: Whole Disk Encryption + SSD David Wright <deblis@lionunicorn.co.uk> - 2021-07-02 05:00 +0200
      Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 05:50 +0200
        Useless use of "dd" Teemu Likonen <tlikonen@iki.fi> - 2021-07-02 07:50 +0200
          Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-02 09:50 +0200
            Re: Useful use of dd [was: Useless use of "dd"] Teemu Likonen <tlikonen@iki.fi> - 2021-07-02 12:30 +0200
              Re: Useful use of dd "Thomas Schmitt" <scdbackup@gmx.net> - 2021-07-02 13:00 +0200
                Re: Useful use of dd <tomas@tuxteam.de> - 2021-07-02 13:20 +0200
                Re: Useful use of dd Teemu Likonen <tlikonen@iki.fi> - 2021-07-02 13:30 +0200
                Re: Useful use of dd David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 23:50 +0200
              Re: Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-02 13:20 +0200
              Re: Useful use of dd Michael Stone <mstone@debian.org> - 2021-07-02 14:50 +0200
              Re: Useful use of dd [was: Useless use of "dd"] Kushal Kumaran <kushal@locationd.net> - 2021-07-02 21:10 +0200
                Creation of empty files [was: Useful use of dd] David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 23:40 +0200
                Re: Creation of empty files [was: Useful use of dd] David Christensen <dpchrist@holgerdanske.com> - 2021-07-03 00:00 +0200
                Re: Creation of empty files [was: Useful use of dd] Michael Stone <mstone@debian.org> - 2021-07-03 15:50 +0200
                Re: Creation of empty files [was: Useful use of dd] David Christensen <dpchrist@holgerdanske.com> - 2021-07-03 23:40 +0200
                Re: Creation of empty files [was: Useful use of dd] Michael Stone <mstone@debian.org> - 2021-07-04 06:00 +0200
            Re: Useful use of dd [was: Useless use of "dd"] Greg Wooledge <greg@wooledge.org> - 2021-07-02 13:40 +0200
              Re: Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-02 13:40 +0200
                Re: Useful use of dd [was: Useless use of "dd"] David Wright <deblis@lionunicorn.co.uk> - 2021-07-02 17:10 +0200
                Re: Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-02 17:40 +0200
                Re: Useful use of dd [was: Useless use of "dd"] Gunnar Gervin <dofeelok@gmail.com> - 2021-07-03 09:20 +0200
                Re: Useful use of dd [was: Useless use of "dd"] <tomas@tuxteam.de> - 2021-07-03 09:30 +0200
            Useless use of shell pipelines [was: Useful use of dd] David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 23:40 +0200
              Re: Useless use of shell pipelines [was: Useful use of dd] l0f4r0@tuta.io - 2021-07-03 10:30 +0200
                Re: Useless use of shell pipelines [was: Useful use of dd] Greg Wooledge <greg@wooledge.org> - 2021-07-03 15:40 +0200
          Re: Useless use of "dd" David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 21:40 +0200
        Re: Whole Disk Encryption + SSD David Wright <deblis@lionunicorn.co.uk> - 2021-07-02 17:10 +0200
          Re: Whole Disk Encryption + SSD Michael Stone <mstone@debian.org> - 2021-07-02 17:30 +0200
          Re: Whole Disk Encryption + SSD David Christensen <dpchrist@holgerdanske.com> - 2021-07-02 20:40 +0200

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