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Re: use of locale in "ls" again (Re: Japanese expression of date)
From: |
Paul Eggert |
Subject: |
Re: use of locale in "ls" again (Re: Japanese expression of date) |
Date: |
Thu, 20 Dec 2001 17:54:12 -0800 (PST) |
> From: Miles Bader <address@hidden>
> Date: 21 Dec 2001 09:56:00 +0900
>
> The main problem I have with this solution is that it seems rather
> unintuitive to see a file that was modified late yesterday as only
> having a time, especially if the file was modified close to 24 hours
> ago. E.g., if it's now 10:30am, and I see a file listed as `10:45:32',
> then it _feels_ like the file was modified today, even though it wasn't
OK. Would you prefer a rule that uses a date for a file modified
yesterday, even if the file is only a few seconds old?
There are a few wrinkles here that may not be immediately obvious
(at least, they weren't obvious to me until just now :-).
* First, ls uses dates for timestamps that are even slightly in the
future. This is intended to be a visual cue that you have clock
skew problems. (It's also required by POSIX, in the POSIX locale.)
E.g. with the current ls:
$ ls -l today future
-rw-rw-r-- 1 eggert src 0 2001-12-20 future
-rw-rw-r-- 1 eggert src 0 12-20 17:20 today
That first file's time stamp is in the future.
This useful property would no longer hold with the changed I
proposed in my previous message, due to daylight saving transition
problems. For example, suppose the clock moves backward by 1 hour
at 2001-10-28 02:00, and we run 'ls' at 23:30 that day on a file
that is dated 00:15 that day. The file is older than 24 hours, so
it'll be labeled with today's date even though there is no clock
skew issue.
* Conversely, the ambiguity of time stamps near a jump-forward DST
change will be a 23-hour ambiguity, not the usual 1-hour ambiguity.
For example, suppose the clock moves forward by 1 hour at 02:00 on
April 1, 2001, and suppose we invoke 'ls' at 02:30 on April 2 on two
files dated 2001-04-01 01:45 and 2001-04-02 01:45, respectively.
Then the output would look like this:
$ ls -l file1 file2
-rw-rw-r-- 1 eggert src 0 01:45:00 file1
-rw-rw-r-- 1 eggert src 0 01:45:00 file2
file1 is 23 hours older than file2, but they appear to have the same
time stamp.
If we decrease the window to less than 24 hours, the
clock-skew-indication problem will get worse. If we increase the
window to greater than 24 hours (to 144 hours, say), we'll need a
day-of-the-week indicator, and this format is just a little bit too
weird even for me:
$ ls -l .profile today
-r--r--r-- 1 eggert eggert 4012 2001-11-20 .profile
-rw-rw-r-- 1 eggert eggert 0 4 16:10:01 today
(That '4' stands for Thursday.) Yuck.
So perhaps it would be simpler and clearer to use a date for a file
last-modified yesterday, even if the file is just a few seconds old.
That's easy to explain, and avoids these confusing situations.
- Re: use of locale in "ls" again (Re: Japanese expression of date), (continued)
- Re: use of locale in "ls" again (Re: Japanese expression of date), Markus Kuhn, 2001/12/20
- Re: use of locale in "ls" again (Re: Japanese expression of date), Paul Eggert, 2001/12/20
- Re: revised use of column space in "ls", Markus Kuhn, 2001/12/20
- Re: revised use of column space in "ls", Miles Bader, 2001/12/20
- Re: revised use of column space in "ls", Paul Eggert, 2001/12/20
- Re: revised use of column space in "ls", Miles Bader, 2001/12/20
- Re: revised use of column space in "ls", Markus Kuhn, 2001/12/20
- Re: revised use of column space in "ls", Paul Eggert, 2001/12/21
- Re: revised use of column space in "ls", Tomohiro KUBOTA, 2001/12/20
- Re: use of locale in "ls" again (Re: Japanese expression of date), Miles Bader, 2001/12/20
- Re: use of locale in "ls" again (Re: Japanese expression of date),
Paul Eggert <=
- Re: use of locale in "ls" again (Re: Japanese expression of date), Miles Bader, 2001/12/20
- Re: use of locale in "ls" again (Re: Japanese expression of date), Paul Jarc, 2001/12/21
- Re: use of locale in "ls" again (Re: Japanese expression of date), Miles Bader, 2001/12/21
- Re: use of locale in "ls" again (Re: Japanese expression of date), Bruno Haible, 2001/12/21
- Re: use of locale in "ls" again (Re: Japanese expression of date), Paul Eggert, 2001/12/21
- Re: use of locale in "ls" again (Re: Japanese expression of date), Tomohiro KUBOTA, 2001/12/20
- Re: use of locale in "ls" again (Re: Japanese expression of date), Paul Jarc, 2001/12/21
- Re: use of locale in "ls" again (Re: Japanese expression of date), Tomohiro KUBOTA, 2001/12/21
- Re: use of locale in "ls" again (Re: Japanese expression of date), Paul Eggert, 2001/12/20
- Re: use of locale in "ls" again (Re: Japanese expression of date), Tomohiro KUBOTA, 2001/12/20