今天用tar解压的时候，发现文件的modify time，只精确到秒。
$ stat linux-6.12.y/Makefile
File: linux-6.12.y/Makefile
Size: 68794 Blocks: 136 IO Block: 4096 regular file
Device: 802h/2050d Inode: 4399981 Links: 1
Access: (0644/-rw-r--r--) Uid: ( 1000/ yuan) Gid: ( 1000/ yuan)
Access: 2025-03-25 14:29:57.669627075 +0800
Modify: 2024-12-18 18:58:52.000000000 +0800
Change: 2025-03-25 14:29:57.669627075 +0800
Birth: -
原来，要默认的gnu格式，不支持纳米精度，需要使用posix格式：
-H posix
或者 --format posix
或者 --posix
$ tar --posix -cf a.tar abc/a
$ tar xf a.tar -C abcd
$ stat abcd/abc/a
File: abcd/abc/a
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: 802h/2050d Inode: 4399987 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 1000/ yuan) Gid: ( 1000/ yuan)
Access: 2025-03-25 15:01:08.434095836 +0800
Modify: 2025-03-25 14:46:14.934762384 +0800
Change: 2025-03-25 15:01:08.434095836 +0800
Birth: -