Re: Contents of file changed while application is reading it

From	"Carlos E.R." <robin_listas@es.invalid>
Newsgroups	comp.os.linux.misc
Subject	Re: Contents of file changed while application is reading it
Date	2023-02-27 10:45 +0100
Message-ID	<5naucjx3rg.ln2@Telcontar.valinor> (permalink)
References	<ttg9pl$301qu$1@dont-email.me> <ttgms9$31hl4$1@dont-email.me>

Show all headers | View raw

On 2023-02-26 23:35, Dan Espen wrote:
> Clark Smith <noaddress@nowhere.net> writes:
> 
>> 	Let's say that I have a C program that is reading the contents of
>> a file, one line at a time, with fgets(). While this is ongoing, the
>> contents of the file are overwritten with new data.
>>
>> 	Is it guaranteed that the C program will continue to have access
>> to the old contents of the file, as long as this program keeps the
>> original file descriptor open?
> 
> If the original file is deleted and a new file created any programs
> that have the old file open won't see any changes.  The file is really
> deleted after all the programs using it close the file.

If the first program keeps the file opened, it can not be actually 
deleted in a Linux filesystem. The first program keeps reading the old 
file till it closes it.

lsof lists them, and marks "deleted" files.


> If the file is actually being updated in place the program will see data
> change subject to buffering issues.
> 

-- 
Cheers, Carlos.

Back to comp.os.linux.misc | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Contents of file changed while application is reading it Clark Smith <noaddress@nowhere.net> - 2023-02-26 18:52 +0000
  Re: Contents of file changed while application is reading it Rich <rich@example.invalid> - 2023-02-26 19:20 +0000
  Re: Contents of file changed while application is reading it Robert Heller <heller@deepsoft.com> - 2023-02-26 21:45 +0000
    Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-26 23:05 +0100
      Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-26 23:38 +0000
    Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-26 23:32 +0000
      Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-02-26 19:06 -0500
        Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-27 00:26 +0000
          Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-02-26 20:48 -0500
          Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-02-27 09:03 +0000
            Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-27 09:58 +0000
              Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 11:16 +0100
              Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-02-27 15:20 +0000
        Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 10:34 +0100
          Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-02-27 09:49 +0000
            Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 11:13 +0100
          Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-27 10:02 +0000
            Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 11:13 +0100
              Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-27 10:17 +0000
                Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-02-27 12:27 -0500
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 19:19 +0100
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-02-27 21:46 -0500
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-28 13:33 +0100
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-02-28 10:49 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-28 16:21 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 01:05 -0500
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-01 21:57 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 22:53 -0500
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-02 19:06 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-02 23:08 -0500
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-03 05:23 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-03 09:36 +0000
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-03-03 11:19 +0100
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-03 15:58 +0000
                Re: Contents of file changed while application is reading it "Carlos E. R." <robin_listas@es.invalid> - 2023-03-03 18:47 +0100
                Re: Contents of file changed while application is reading it Rich <rich@example.invalid> - 2023-03-04 16:24 +0000
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-03-04 18:40 +0100
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-03 18:44 +0000
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-04 01:25 +0000
                Re: Contents of file changed while application is reading it Rich <rich@example.invalid> - 2023-03-04 16:21 +0000
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-04 23:55 -0500
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-05 05:35 +0000
                Re: Contents of file changed while application is reading it Allodoxaphobia <trepidation@example.net> - 2023-03-05 13:48 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-05 14:01 +0000
                Re: Contents of file changed while application is reading it Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2023-03-05 19:16 +0000
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 00:43 -0500
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 00:42 -0500
                Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-02-28 12:01 -0500
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 01:17 -0500
                Re: Contents of file changed while application is reading it Robert Riches <spamtrap42@jacob21819.net> - 2023-02-28 04:13 +0000
                Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-28 13:16 +0100
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 01:32 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-01 10:30 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-01 22:48 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-02 09:41 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-02 23:39 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-03 09:28 +0000
                Re: Contents of file changed while application is reading it "David W. Hodgins" <dwhodgins@nomail.afraid.org> - 2023-03-03 12:16 -0500
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-04 01:36 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-04 07:15 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-04 02:47 -0500
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-04 01:12 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-04 06:51 +0000
                Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-03-04 03:32 -0500
                Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-03-04 09:54 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-04 10:09 +0000
                Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-03-04 11:22 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-04 11:58 +0000
                Re: Contents of file changed while application is reading it Richard Kettlewell <invalid@invalid.invalid> - 2023-03-05 16:43 +0000
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-06 09:20 +0000
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-04 20:24 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-05 13:40 +0000
                Re: Contents of file changed while application is reading it Dan Espen <dan1espen@gmail.com> - 2023-03-05 11:29 -0500
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 01:21 -0500
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 01:06 -0500
                Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-03-06 09:28 +0000
                Re: Contents of file changed while application is reading it "28B.I874" <28B.I874@noabzba.net> - 2023-03-06 08:54 -0500
  Re: Contents of file changed while application is reading it Dan Espen <dan1espen@gmail.com> - 2023-02-26 17:35 -0500
    Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-26 23:39 +0000
      Re: Contents of file changed while application is reading it "28A.I873" <28A.I873@noabzba.net> - 2023-02-26 22:42 -0500
    Re: Contents of file changed while application is reading it "Carlos E.R." <robin_listas@es.invalid> - 2023-02-27 10:45 +0100
  Re: Contents of file changed while application is reading it The Natural Philosopher <tnp@invalid.invalid> - 2023-02-26 23:31 +0000

csiph-web