Sorting ls output by date in filename, in reverse order

Question

I can generate output sorted by date in "normal order" with the following command:

ls -A -lR | grep "^-" | sed "s/.\{43\}/&\n/" | grep -v "^-" | while read ONELINE; do if echo $ONELINE | cut -d " " -f3 | grep -o '[0-9][0-9]:[0-9][0-9]' > /dev/null 2>&1; then echo $ONELINE | sed "s/.\{7\}/&$(date +%Y) /"; else echo $ONELINE; fi; done

Result:

Jan 23 2011 10:42 SOMETHING 2007.12.20.avi
Jun 26 2009 SOMETHING 2009.06.25.avi
Feb 12 2010 SOMETHING 2010.02.11.avi
Jan 29 2011 09:17 SOMETHING 2011.01.27.avi
Feb 11 2011 20:06 SOMETHING 2011.02.10.avi
Feb 27 2011 23:05 SOMETHING 2011.02.24.avi

How could I get the output where the newest file is at the top, like this:

Feb 27 2011 23:05 SOMETHING 2011.02.24.avi
Feb 11 2011 20:06 SOMETHING 2011.02.10.avi
Jan 29 2011 09:17 SOMETHING 2011.01.27.avi
Jan 23 2011 10:42 SOMETHING 2007.12.20.avi
Feb 12 2010 SOMETHING 2010.02.11.avi
Jun 26 2009 SOMETHING 2009.06.25.avi

@user4724: That doesn't generate the same type of outpout for me that you have - no matter as Gilles has [the answer](http://unix.stackexchange.com/questions/8352/sorting-by-date/8359#8359) — , Feb 28 '11 at 21:46

score 31 · Answer 1 · edited Jun 28 '12 at 18:30

31

On most unices, ls has a -t option. From the man page of my Debian box:

-t sort by modification time

Try the following command:

$ ls -lt

edited Jun 28 '12 at 18:30

rahmu

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answered Feb 28 '11 at 20:34

Alexander Pogrebnyak

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i need it recursively, sorry – LanceBaynes Feb 28 '11 at 21:21
+ls -lt will list a full directory, if 1 file changes in it. – LanceBaynes Feb 28 '11 at 21:22
The directories and files both not sorting for me as `ls -ltr` on CentOS Linux release 7.9.2009 – Chaminda Bandara Mar 09 '22 at 10:01
@ChamindaBandara we're 10 years on from this answer, so you're probably better asking a new question. Reference this one, and provide not only the command you're using but also example input and results showing how it's not working for you – roaima Mar 09 '22 at 15:51

score 20 · Answer 2 · edited Apr 13 '17 at 12:37

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Is that a text file you're trying to sort, or are you trying to view a directory listing by date? For the latter, use the -t flag to ls. For the former, see in particular the -M flag to GNU sort, which sorts by three-letter month name abbreviations. The following command sorts by the 3rd, 1st, 2nd and 4th columns, treating the second sort key as a month name.

sort -k 3 -k 1M -k2 -k4 in.txt

Do consider always using Japanese/ISO style dates, always in the order YYYY-MM-DD-HH-MM-SS (i.e. most significant first, constant column width). This way sorting by date is identical to a lexicographic sort.

edited Apr 13 '17 at 12:37

Community

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answered Feb 28 '11 at 21:20

Gilles 'SO- stop being evil'

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Don't forget the leading zeroes on that date format suggestion. This is the format I use whenever I format the string myself. – stolenmoment May 26 '18 at 09:39
@stolenmoment You can use spaces instead of zeros if you don't mind spaces, the important point is a constant column with. `2018 5 26` works just as well as `2018 05 26` (as long as you don't go through markup that merges consecutive spaces…), what doesn't work well is `2018 5 26`. – Gilles 'SO- stop being evil' May 26 '18 at 10:39
Yeah, I reflexively avoid spaces in filenames, I'm sure you can guess why. – stolenmoment May 26 '18 at 11:34

score 7 · Answer 3 · edited Feb 17 '17 at 20:58

7

I’m not sure if the functionality was in the ls command when the original question was asked, but now you can use the option --full-time.

e.g.,

ls -t --full-time

will sort with oldest time at the bottom; or if you use:

ls -tr --full-time

then it will reverse the order.

edited Feb 17 '17 at 20:58

G-Man Says 'Reinstate Monica'

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answered Feb 17 '17 at 20:23

Bevan Thomas

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The question is about how to sort file by modification date/time. The `-t` option answers that question completely; `--full-time` isn’t really relevant. – G-Man Says 'Reinstate Monica' Feb 17 '17 at 21:05
The only thing -t option doesn't give you the year for files modified within six months where as --full-time gives you exactly that. You can also use time-style to format a date format to you liking. e.g ls -ltr --time-style+%Y-%m-%d\ %H:%M:%S – Bevan Thomas Feb 20 '17 at 08:35
I’m not sure what your point is. `ls -t` doesn’t give you mode and owner of the files, the host name and operating system version, or the price of tea in China, either. `ls -t` doesn’t even display the modification date at all. But the question isn’t about displaying file information, it’s about sorting files by modification date. You are not contributing to the answer of the question; you are adding nice-to-know supplementary information. When you get 50 [reputation points](/help/whats-reputation), you can post that sort of information as a [comment](/help/privileges/comment). – G-Man Says 'Reinstate Monica' Feb 21 '17 at 00:52
Even though `ls -t` does not show other info(mode/owner/group), adding `-l` will do. I use `ll -t` and `ll` is a common alias `ls -l` which solves the problem. For me, it is confusing at first that for changes older than 6 months, the year columns shows year, while when it's <6 months old, it's showing hours; and `--full-time` solves that. For me it's valid answer. @G-ManSays'ReinstateMonica' – WesternGun Feb 14 '22 at 11:49

Chip Grandits · Answer 4 · 2022-01-18T16:42:13.347

I like the approach of using sort posted in the answer by Gilles 'SO- stop being evil', but it's not quite all the way there. First, technically the OP wants reverse chronological order, not forward, and so r needs to be addd to the sort criterial.
So starting with sort -k 3r -k 1Mr -k 2r -k 4r se.txt that would give you

Feb 27 2011 23:05 SOMETHING 2011.02.24.avi
Feb 11 2011 20:06 SOMETHING 2011.02.10.avi
Jan 23 2011 10:42 SOMETHING 2007.12.20.avi
Jan 29 2011 09:17 SOMETHING 2011.01.27.avi
Feb 12 2010 SOMETHING 2010.02.11.avi
Jun 26 2009 SOMETHING 2009.06.25.avi

But look closely and you'll note Jan 23, 2011 and Jan 29, 2011 are in the wrong order. This is due to a subtle bug, or perhaps unclear documentation in sort. An individual sort KEYDEF such as -k2 means starting from field 2, not only on field 2. It is best to also specify the stopping field as well (e.g. -k2,2 means sorting from field 2 to field 2, i.e. only field 2).

And so

sort -k 3,3r -k 1,1Mr -k 2,2r -k 4,4r

yields the correct results. (I was able to get this to work by setting only some of the stop fields in the KEYDEFs, but I don't know which are necessary and why, so it seems best to specify them all. Well, except maybe the last one, but then in the OP input file there are some records with 4 fields and some with 5 so the 4th field is not always the final field)

It's not a bug, it's as clearly specified in the manuals of most sort implementations and in the POSIX specification. See also [Sort based on the third column](//unix.stackexchange.com/q/104525) — Stéphane Chazelas, Jan 18 '22 at 17:08
I read GNU and BSD man pages. It is not clear at all to me why the first sort in my post fails. (Ignoring the 2 records that are only 4 fields)., it sorts 1st time by year-field then time-field then other things; 2nd time, using month criteria, by month-field, then day field, then time-field, then other things; 3rd time by day-field, then year-field, then time field, then other things, 4th time by other things. My reading of man page is that the day fields (col 2) get correctly sorted in the 3rd pass, and nothing should happen in the 4th (col 4+) pass to knock them out of order. — Chip Grandits, Jan 18 '22 at 19:33

score -3 · Answer 5 · edited Nov 17 '16 at 13:03

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recursive (R) and pause (|more)

ls -ltR |more

edited Nov 17 '16 at 13:03

techraf

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answered Nov 17 '16 at 12:36

Henrique

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Sorting ls output by date in filename, in reverse order

5 Answers5