Question

我使用stat来获取文件的访问时间（当前日期是2013年10月23日）

[juan@JN-LNXSVR-02 labfiles]$ stat nursery
  File: `nursery'
  Size: 837         Blocks: 8          IO Block: 4096   regular file
Device: fd00h/64768d    Inode: 139539      Links: 1
Access: (0644/-rw-r--r--)  Uid: (  500/    juan)   Gid: (  500/    juan)
Access: 2013-10-22 18:03:20.703888346 -0400
Modify: 2013-10-21 16:57:07.801165793 -0400

然后我编辑文件并关闭它而不做任何修改，然后再次提交stat

juan@JN-LNXSVR-02 labfiles]$ vi nursery
[juan@JN-LNXSVR-02 labfiles]$ stat nursery
  File: `nursery'
  Size: 837         Blocks: 8          IO Block: 4096   regular file
Device: fd00h/64768d    Inode: 139539      Links: 1
Access: (0644/-rw-r--r--)  Uid: (  500/    juan)   Gid: (  500/    juan)
Access: 2013-10-22 18:03:20.703888346 -0400
Modify: 2013-10-21 16:57:07.801165793 -0400
Change: 2013-10-21 16:57:07.801165793 -0400

但访问时间没有变化，为什么？

我找不到任何noatime属性

juan@JN-LNXSVR-02 labfiles]$ grep noatime /proc/mounts
[juan@JN-LNXSVR-02 labfiles]$

mount命令的输出是

[juan@JN-LNXSVR-02 labfiles]$ mount

/dev/mapper/vg_jnlnxsvr02-lv_root on / type ext4 (rw)

proc on /proc type proc (rw)

sysfs on /sys type sysfs (rw) 

devpts on /dev/pts type devpts (rw,gid=5,mode=620) 

tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0")


/dev/sda1 on /boot type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)

sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)

[juan@JN-LNXSVR-02 labfiles]$

Answer 1

您可以包含mount的输出吗？也许你的磁盘装有noatime？

编辑（再次）：relatime只会在修改后读取一次但不是每次都更新一次。从Linux 2.6.30开始，这似乎是标准选项，因此如果你执行write + read，它会在读取时更新。但是write + read + read只会在第一次阅读时更新它（并且每次修改后都会更新一次）。

鉴于您的访问时间已经比修改时间更新，如果您使用relatime（或没有atime选项）挂载，则访问时间不会更新只读。

来自man mount：

noatime
 Do not update inode access times on this filesystem (e.g., for faster access on
 the news spool to speed up news servers).

relatime
 Update  inode  access  times relative to modify or change time.  Access time is
 only updated if the previous access time was earlier than the current modify or
 change  time. (Similar to noatime, but doesn't break mutt or other applications
 that need to know if a file has been read since the last time it was modified.)
 Since Linux 2.6.30, the kernel defaults to the behavior provided by this option
 (unless  noatime  was   specified),  and  the strictatime option is required to
 obtain traditional semantics. In addition, since Linux 2.6.30, the file's  last
 access time is always  updated  if  it  is more than 1 day old.

为了记录，如果您想要恢复原来的行为，请使用strictatime。

Allows to explicitly requesting full atime updates. This makes it possible for
kernel to defaults to relatime or noatime but still allow userspace to override
it. For more details about the default system mount options see /proc/mounts.

打开文件后，访问时间不会更改

1 个答案: