[Linux] 文件的atime、mtime和ctime

刺骨的言语ヽ痛彻心扉 2023-06-30 08:56 3阅读 0赞

1.使用stat命令查看文件的三个时间  
新创建的文件atime,mtime,ctime是一样的，也就是创建时间，但是之后再想查创建时间没有找到方法。

[root@xxx testtime]# ls -l
    total 12
    -rw-r--r--. 1 root root 4 Jan 16 11:22 aaa.txt
    -rw-r--r--. 1 root root 4 Jan 16 11:23 bbb.txt
    -rw-r--r--. 1 root root 4 Jan 16 11:23 ccc.txt
    [root@xxx testtime]# stat aaa.txt
      File: ‘aaa.txt’
      Size: 4               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796504   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:22:55.902450877 +0800
    Modify: 2020-01-16 11:22:55.902450877 +0800
    Change: 2020-01-16 11:22:55.902450877 +0800
     Birth: -
    [root@xxx testtime]#

三种时间的介绍  
atime(Access Time) -文件的最近访问时间(cat、vim等)  
mtime(Modify Time) -文件的内容最近修改的时间(vim编辑,重定向写入等)  
ctime(Change Time) -文件属性最近修改的时间(内容、路径、所有者、权限等变化)

（1）使用cat命令查看文件，仅atime会更新

[root@xxx testtime]# cat aaa.txt
    aaa
    [root@xxx testtime]# stat aaa.txt
      File: ‘aaa.txt’
      Size: 4               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796504   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:26:10.860493954 +0800
    Modify: 2020-01-16 11:22:55.902450877 +0800
    Change: 2020-01-16 11:22:55.902450877 +0800
     Birth: -
    [root@xxx testtime]#

（2）使用vim命令查看文件但不修改(:q)，仅atime会更新；修改内容(:wq)，三个时间都会更新

[root@xxx testtime]# vim aaa.txt
    [root@xxx testtime]# stat aaa.txt
      File: ‘aaa.txt’
      Size: 4               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796507   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:27:29.221913212 +0800
    Modify: 2020-01-16 11:27:29.221913212 +0800
    Change: 2020-01-16 11:27:29.291913584 +0800
     Birth: -
    [root@xxx testtime]#

（3）使用重定向追加内容到文件，会更新mtime和ctime，由于并没有读原文件内容atime不更新

[root@xxx testtime]# stat bbb.txt
      File: ‘bbb.txt’
      Size: 4               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796505   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:23:06.606508142 +0800
    Modify: 2020-01-16 11:23:06.606508142 +0800
    Change: 2020-01-16 11:23:06.606508142 +0800
     Birth: -
    [root@xxx testtime]# cat aaa.txt >> bbb.txt
    [root@xxx testtime]# stat bbb.txt
      File: ‘bbb.txt’
      Size: 8               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796505   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:23:06.606508142 +0800
    Modify: 2020-01-16 11:28:23.973206143 +0800
    Change: 2020-01-16 11:28:23.973206143 +0800
     Birth: -
    [root@xxx testtime]#

（4）改变文件路径，仅ctime会更新

[root@xxx testtime]# stat aaa.txt
      File: ‘aaa.txt’
      Size: 4               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796507   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:28:23.973206143 +0800
    Modify: 2020-01-16 11:27:29.221913212 +0800
    Change: 2020-01-16 11:27:29.291913584 +0800
     Birth: -
    [root@xxx testtime]#
    [root@xxx testtime]# mv aaa.txt ../;cd ..;stat aaa.txt
      File: ‘aaa.txt’
      Size: 4               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796507   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:28:23.973206143 +0800
    Modify: 2020-01-16 11:27:29.221913212 +0800
    Change: 2020-01-16 11:56:17.259158698 +0800
     Birth: -
    [root@xxx test]#

2.使用touch指令修改时间  
(1) touch -a更新atime(ctime也会更新)

[root@xxx testtime]# date;touch -a bbb.txt
    Thu Jan 16 11:29:11 CST 2020
    [root@xxx testtime]# stat bbb.txt
      File: ‘bbb.txt’
      Size: 8               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796505   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:29:11.802462045 +0800
    Modify: 2020-01-16 11:28:23.973206143 +0800
    Change: 2020-01-16 11:29:11.802462045 +0800
     Birth: -
    [root@xxx testtime]#

使用touch不带选项会更新三个时间

[root@xxx testtime]# date;touch bbb.txt;stat bbb.txt
    Thu Jan 16 11:32:22 CST 2020
      File: ‘bbb.txt’
      Size: 8               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796505   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 11:32:22.494482300 +0800
    Modify: 2020-01-16 11:32:22.494482300 +0800
    Change: 2020-01-16 11:32:22.494482300 +0800
     Birth: -
    [root@xxx testtime]#

(2) touch -d 使用指定的日期来修改

[root@xxx testtime]# touch -d "06:00:00" bbb.txt;stat bbb.txt
      File: ‘bbb.txt’
      Size: 8               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796505   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 06:00:00.000000000 +0800
    Modify: 2020-01-16 06:00:00.000000000 +0800
    Change: 2020-01-16 11:39:25.439745178 +0800
     Birth: -
    [root@xxx testtime]#

(3)用某文件的时间来设置另一个文件的时间，会复制atime和mtime，ctime根据当前时间更新  
例如用bbb.txt的时间来设置ccc.txt的时间

[root@xxx testtime]# date;touch -r bbb.txt ccc.txt;stat ccc.txt
    Thu Jan 16 11:41:06 CST 2020
      File: ‘ccc.txt’
      Size: 4               Blocks: 8          IO Block: 4096   regular file
    Device: fd00h/64768d    Inode: 134796506   Links: 1
    Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
    Context: unconfined_u:object_r:var_t:s0
    Access: 2020-01-16 06:00:00.000000000 +0800
    Modify: 2020-01-16 06:00:00.000000000 +0800
    Change: 2020-01-16 11:41:06.349285070 +0800
     Birth: -
    [root@xxx testtime]#

参考资料：  
查看文件的创建、修改时间 https://www.cnblogs.com/yizhipanghu/p/9634325.html  
Linux系统stat指令用法 https://www.cnblogs.com/klb561/p/9241228.html