Re: Extract last email from an email file (mbox format)

On Sun, May 29, 2016 at 5:35 AM, udi M <[email protected]> wrote:
>
>
> On 27/05/16 22:45, Xu Wang wrote:
>>
>> On Fri, May 27, 2016 at 10:09 AM, Zhiliang Hu <[email protected]> wrote:
>>>
>>> On Thu, 26 May 2016, Xu Wang wrote:
>>>
>>>> Date: Thu, 26 May 2016 21:03:15 -0400
>>>> From: Xu Wang <[email protected]>
>>>> Subject: Re: Extract last email from an email file (mbox format)
>>>>
>>>> Hello, this is....
>>>> From: will this be matched?
>>>>>
>>>>>  From how about this one?
>>>>
>>>> ---------------------------------end last message
>>>>
>>>> So this is why I am not sure matching regex with "^From " is safe. It
>>>> will also match in the body.
>>>
>>>
>>> As a tradition, when a mail is saved into mbox format, any leading "From"
>>> line is prefixed with ">" as in your example.
>>
>> I see, so mutt must not be using mbox format then because it does not do
>> that.
>>
>>> You could use 'H' or 'h' flag in your little rc file to check headers
>>> only.
>>
>> What would be the full contents of little rc in this case?
>
> I do not know what  Zhiliang  means, but,  I am afraid that you
> did not check my last suggestion:  By using formail(1) + tee(1)
> you do not need any rc file !
>
> Do only one simple command:
>
>     formail  -s  tee oneMessageOnly < theBigBox
>
>
> 1.   formail  works only on the headers (was dsiged for)

Agreed.

> 2.   It will not create a big directory !

Agreed.

> 3.   It is fast.

Unfortunately not for me.

time formail  -s  tee oneMessageOnly < theBigBox

real 0m24.019s
user 0m3.376s
sys 0m4.484s

As mentioned, my file is huge:
$ wc -l theBigBox
2171183 theBigBox

And it will get huger. THe main thing though is I would like to
eventually make my script open source and help others and want to
allow them to have huge files as well.

I would like use this in script and use it often so 24 seconds is too
much for me.

Udi, thank you so much for your continued help and explanations. I
really appreciate your time!

Kind regards,

Xu

>
> --udi