From: alberttresens on

Hi,
I am trying to get the creation time of a file to be able to correlate it's
content timestamps with other log files.
In order to get the creation time of the file one a Linux machine i used:

return os.lstat(logFile)[ST_CTIME]

That returns to me something like: 1279620166

I would like to know the meaning of this number.
Is it in seconds since the epoch?
Or is some other respresentation?

Thanks,
Albert
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From: alberttresens on

Hi, thanks for the reply.

But what i am more concerned about, as I am trying to correlate logs, is
what is the timestamp:
1279620166 mean?
Is it seconds since the epoch or the ISO time in seconds?

Any idea?

Thanks a lot!!


Steven D'Aprano-7 wrote:
>
> On Mon, 26 Jul 2010 09:54:23 -0700, alberttresens wrote:
>
>> Hi,
>> I am trying to get the creation time of a file to be able to correlate
>> it's content timestamps with other log files. In order to get the
>> creation time of the file one a Linux machine i used:
>
> You're out of luck. Neither Unix nor Linux store the creation time of
> files, at least not on any file system I know of. It stores three
> timestamps: mtime, ctime, and atime.
>
> atime is the simple one -- it is "access time", or when the file was last
> read.
>
> mtime is "modification time" -- it is when the file *contents* were last
> changed.
>
> But ctime is NOT creation time, as many people imagine. It is "change
> time", and it changes whenever EITHER the file contents are changed, OR
> when the file metadata (permissions, owner, name, etc.) change.
>
> So any time mtime changes, so does ctime. But not visa versa.
>
>
>> return os.lstat(logFile)[ST_CTIME]
>>
>> That returns to me something like: 1279620166
>>
>> I would like to know the meaning of this number. Is it in seconds since
>> the epoch?
>
> Yes.
>
>
>
>
> --
> Steven
> --
> http://mail.python.org/mailman/listinfo/python-list
>
>

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From: Thomas Jollans on
On 07/26/2010 07:24 PM, alberttresens wrote:
>
> Hi, thanks for the reply.

Alas, you didn't actually read it:

>
> But what i am more concerned about, as I am trying to correlate logs, is
> what is the timestamp:
> 1279620166 mean?
> Is it seconds since the epoch or the ISO time in seconds?
>
> Any idea?
>
> Thanks a lot!!
>

[...]

>>> I would like to know the meaning of this number. Is it in seconds since
>>> the epoch?
>>
>> Yes.

You quoted the answer to your question in the same e-mail. fascinating.

A little side note:

>> atime is the simple one -- it is "access time", or when the file was
>> last read.

You should never rely on this, though: some file systems don't store
this (I think) and many users/sysadmins actually disable this
(mount -o noatime) for performance reasons. (Also, on an SSD, I imagine
enabling atime, and with it many, many additional writes, could
noticeably detriment disk lifetime)