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

Answer 1

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

Answer 2

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.

Answer 3

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.

Answer 4

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)

Answer 5

This will list all files recursively with ls output and reverse sorted by modified time (mtime):

find -print0 -type f directory_path | xargs -0 ls -ltr

Peform the search more quickly with fd

fd -0 -t f directory_path | xargs -0 ls -ltr

Answer 6

With the standard -t option, ls will sort files (given as arguments or found in the contents of directories passed argument) by modification time from newest to oldest.

With the -R option, ls enters a recursive mode, but it still lists the contents of each directory separately, so while each directory listing will be listed by modification time, you won't get a notion of the relative time of files between different directories. The files will also not be listed with their full path.

To list files recursively with their full paths, ordered by time, you'd need to pass all of them by path to ls. You could do it with:

LC_ALL=C find . -name . -o -name '.*' -prune -o -exec ls -ltd {} +

(-name . -o -name '.*' -prune -o with LC_ALL=C to exclude hidden files, like ls does by default without -a/-A when it lists the contents of directories itself)

But that will break as soon as there are so many files that find needs to call ls several times to work around the execve() limit on the size or argument+environment that can be passed to a command, where you'll end up with several independent sorted lists.

To address that, you'd need to sort the list outside of ls and pass the list to those several invocations of ls -ld. With the zsh shell and a xargs that supports the -0 and -r option, that can be done with:

print -rNC1 -- **/*(Nom) | xargs -r0 ls -ltd --

If your ls supports the non-standard -U option to skip sorting, you can use that in place of -t as zsh has already sorted the list with its om (order by modification time) glob qualifier. Add the D glob qualifier if you want hidden files to be included.

With the GNU implementations of find, ls, cut and sort, you can also do:

LC_ALL=C find . -name . -o -name '.*' -prune -o -printf '%T@\t%P\0' |
  sort -rzn |
  cut -zf2- |
  xargs -r0 ls -lUd --

Answer 7

recursive (R) and pause (|more)

ls -ltR |more