How to find the directory with latest modified content??

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http://www.linuxquestions.org – Hi, I want to know how to find the latest modified directory. I know that the command 'ls -rtl' gives the latest modified file/directory at the end. But my specific requirement is: If I create two directories named dir1, dir2 in the same order. so now my latest modified directory is "dir2". Now inside each directories, I created a file. Now in the last, I modify the file in "dir1". So overall, the content of dir1 got modified recently. If I use the command 'ls -rtl', this will still show dir2 as latest, as it is created recently. But I want the directory in which any int (HowTos)