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

On Mon, May 30, 2016 at 6:12 AM, udi M <[email protected]> wrote:
>
>
> On 29/05/16 23:11, Xu Wang wrote:
>>
>> 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.
>
>
> My testoffers compromise:
>
> TIMEFORMAT=%2R
>
> #> wc -l ./old-y06/toro/mail/mail-orig/sent-mail-mar-2006
> 4017303 ./old-y06/toro/mail/mail-orig/sent-mail-mar-2006
>
> #>  time formail -s tee xxx <
> ./old-y06/toro/mail/mail-orig/sent-mail-mar-2006
> ...output...
> ...output...
> 70.50
>
> #>  time formail -s tee xxx <
> ./old-y06/toro/mail/mail-orig/sent-mail-mar-2006 >/dev/null
> 10.49

Ah yes that is great improvement! For me as well. Redirecting is a good idea.

>
> Running the tac(1) is much! faster! but, you the pipe call three jobs
> parallel but the
> last tac(1) (in the right side) must wait for the left jobs to finish, maybe
> needs more
> memory. As you mentioned it is dilemma, if the script supposed to run in
> background
> the time is less problematic - it is your choice.

OK I will consider all possibilities. Thank you so much for the helping.

Highest regards,

Xu

>
>
>
>
>>
>> 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
>
>