简单的ctime，atime和mtime区别说明

Posted 2022-01-26 sushisuren

简单写写ctime，atime和mtime的区别。
有些教程写的比较复杂，其实简单的很：
atime 就是access time 访问就会改变，无论是cat还是more，只要访问过，就会变。不影响另外两个。
ctime 是change time ，主要是修改权限、所有者才会变，chmod +x ,就会单独修改此时间。不影响另外两个。
如下，修改权限+x后change time 发生变化，其他两个未变

an@an-Y7000:~$ stat 1File: 1
  Size: 509             Blocks: 8          IO Block: 4096   regular file
Device: 810h/2064d      Inode: 2003        Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/      an)   Gid: ( 1000/      an)
Access: 2022-01-25 16:02:38.020978784 +0800
Modify: 2022-01-11 14:43:12.387342409 +0800
Change: 2022-01-11 14:43:12.387342409 +0800
 Birth: -
an@an-Y7000:~$ chmod +x 1
an@an-Y7000:~$ stat 1
  File: 1
  Size: 509             Blocks: 8          IO Block: 4096   regular file
Device: 810h/2064d      Inode: 2003        Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/      an)   Gid: ( 1000/      an)
Access: 2022-01-25 16:02:38.020978784 +0800
Modify: 2022-01-11 14:43:12.387342409 +0800
Change: 2022-01-25 16:02:46.030978913 +0800
 Birth: -

mtime 是modify time，未修改过内容，就是创建时间，之后如修改过内容则此时间会变，如用的vim同时 会把atime,ctime 一起修改。
如下，修改一下文本内容，则3个时间一起改变：

an@an-Y7000:~$ stat t.py
  File: t.py
  Size: 98              Blocks: 8          IO Block: 4096   regular file
Device: 810h/2064d      Inode: 15026       Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/      an)   Gid: ( 1000/      an)
Access: 2022-01-01 14:44:59.063923653 +0800
Modify: 2021-11-01 16:14:43.816264464 +0800
Change: 2021-11-01 16:14:43.826264464 +0800
 Birth: -
an@an-Y7000:~$ vim t.py
an@an-Y7000:~$ stat t.py
  File: t.py
  Size: 104             Blocks: 8          IO Block: 4096   regular file
Device: 810h/2064d      Inode: 8148        Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/      an)   Gid: ( 1000/      an)
Access: 2022-01-25 16:13:18.420989114 +0800
Modify: 2022-01-25 16:13:18.420989114 +0800
Change: 2022-01-25 16:13:18.430989114 +0800
 Birth: -

如只是追加，则只会修改mtime和ctime ，不会修改access time.

an@an-Y7000:~$ stat test.py
  File: test.py
  Size: 1022            Blocks: 8          IO Block: 4096   regular file
Device: 810h/2064d      Inode: 218         Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/      an)   Gid: ( 1000/      an)
Access: 2022-01-01 10:15:36.678685565 +0800
Modify: 2021-10-02 19:52:35.890585412 +0800
Change: 2021-10-02 19:52:35.900585412 +0800
 Birth: -

追加文本后，ctime 和mtime 发生改变，atime 未变化

an@an-Y7000:~$ echo "###TEST">> test.py
an@an-Y7000:~$ stat test.py
  File: test.py
  Size: 1030            Blocks: 8          IO Block: 4096   regular file
Device: 810h/2064d      Inode: 218         Links: 1
Access: (0755/-rwxr-xr-x)  Uid: ( 1000/      an)   Gid: ( 1000/      an)
Access: 2022-01-01 10:15:36.678685565 +0800
Modify: 2022-01-25 16:32:03.501007262 +0800
Change: 2022-01-25 16:32:03.501007262 +0800
 Birth: -