将目录时间戳设置为最近修改的文件（递归地）

Question

如何更改目录以及该目录中所有子文件夹的时间戳以反映所包含文件的修改时间？

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例如，使用以下目录结构：

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[Jan 9]  root\n\xe2\x94\x9c\xe2\x94\x80\xe2\x94\x80 [Jan 3]  file1\n\xe2\x94\x9c\xe2\x94\x80\xe2\x94\x80 [Jan 7]  file2\n\xe2\x94\x9c\xe2\x94\x80\xe2\x94\x80 [Jan 6]  sub1\n\xe2\x94\x82\xc2\xa0\xc2\xa0 \xe2\x94\x9c\xe2\x94\x80\xe2\x94\x80 [Jan 2]  file3\n\xe2\x94\x82\xc2\xa0\xc2\xa0 \xe2\x94\x94\xe2\x94\x80\xe2\x94\x80 [Jan 1]  file4\n\xe2\x94\x94\xe2\x94\x80\xe2\x94\x80 [Jan  4] sub2\n    \xe2\x94\x94\xe2\x94\x80\xe2\x94\x80 [Jan 8]  file5\n

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这是生成该内容的单行代码：

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mkdir -p root/sub1 root/sub2 && touch -d '2018-01-08' root/sub2/file5 && touch -d '2018-01-04' root/sub2/ && touch -d '2018-01-01' root/sub1/file4 && touch -d '2018-01-02' root/sub1/file3 && touch -d '2018-01-06' root/sub1/ && touch -d '2018-01-07' root/file2 && touch -d '2018-01-03' root/file1 && touch -d '2018-01-09' root/\n

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它可以列出tree -D

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我想将三个目录的时间戳更改为：

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[Jan 8]  root\n\xe2\x94\x9c\xe2\x94\x80\xe2\x94\x80 [Jan 3]  file1\n\xe2\x94\x9c\xe2\x94\x80\xe2\x94\x80 [Jan 7]  file2\n\xe2\x94\x9c\xe2\x94\x80\xe2\x94\x80 [Jan 2]  sub1\n\xe2\x94\x82\xc2\xa0\xc2\xa0 \xe2\x94\x9c\xe2\x94\x80\xe2\x94\x80 [Jan 2]  file3\n\xe2\x94\x82\xc2\xa0\xc2\xa0 \xe2\x94\x94\xe2\x94\x80\xe2\x94\x80 [Jan 1]  file4\n\xe2\x94\x94\xe2\x94\x80\xe2\x94\x80 [Jan 8]  sub2\n    \xe2\x94\x94\xe2\x94\x80\xe2\x94\x80 [Jan 8]  file5\n

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笔记：

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• 目录上的当前时间戳将被完全忽略，新的时间戳仅根据内容设置。
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• 时间戳会冒泡到父目录的多个级别。
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The reason that I'm doing this is for a directory that gets copied with rsync. The directory is checked into git and could get rsynced from any place that has the repository checked out. To ensure that rsync is consistent and idempotent from the various places, I need to ensure that the time stamps and permissions of everything are in a known state. I already have a script that sets the timestamps of files based on when they were committed to git. I also have a script that sets the permissions on all files and directories to a known state. The only portion that I'm struggling with is bubbling time stamps from the files up to parent directories.

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I would like one line or short script that I can run from the command line to set directory timestamps based on the timestamps of their contents.

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Answer 1

Unless I'm overlooking something (haven't tested this extensively):

find . -depth -type d -execdir \
    sh -c 'touch "$PWD/$0" -r "$PWD/$0/$( ls -t "$PWD/$0" | head -n 1 )"' \
    {} \;

What it does:

• finds all subdirectories of .
• fetches their full names
• with ls -t, lists their contents in reverse datetime order and gets the first
• uses touch to touch the directory using its newest object as timestamp

For correct datetime "bubbling", the -depth option ensures that subdirectories are processed before the current subdirectory ("depth first"). Once the subdirectories have been processed and their datetimes updated, the current directory is processed (and possibly inherits one of the daughter subdirectories' timestamp).