Date: Sat, 24 Oct 2009 18:02:16 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Paul Schmehl <pschmehl_lists_nada@tx.rr.com> Cc: Kelly Martin <kellymartin@gmail.com>, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: changing cron's From: address in emails Message-ID: <4AE33318.2040000@infracaninophile.co.uk> In-Reply-To: <D79559A491F151EA3B0703A4@[10.0.0.20]> References: <1338880b0910240008h5d5e7846q8ccf184728d9e036@mail.gmail.com> <4AE2C5F4.20109@infracaninophile.co.uk> <D79559A491F151EA3B0703A4@[10.0.0.20]>
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Paul Schmehl wrote:
> --On Saturday, October 24, 2009 4:16 AM -0500 Matthew Seaman=20
> <m.seaman@infracaninophile.co.uk> wrote:
>=20
>> Kelly Martin wrote:
>>> Greetings, here's a simple question for the FreeBSD gurus out there. =
I
>>> have several servers running cron scripts daily for me, and they all
>>> send me e-mail with their output. Regardless of which server it is,
>>> each of these e-mails have the From: address looking exactly the same=
=2E
>>> They all say they are from the "Cron Daemon". Fine, but I'd like to
>>> know more clearly which server the cron output is from.
>>>
>>> How can I change the From: address of these emails to "Myserver Cron
>>> Daemon" instead? I know cron runs as the user, so it's not immediatel=
y
>>> obvious to me how to change the From: field. Already the subject line=
>>> says something like "Cron <root@Myserver> ..." but this doesn't stand=
>>> out enough for my tired eyes.
>>
>> Hmmm... that's actually quite tricky. There's no facility within
>> cron(8) for changing the address it sends /from/, and as the bit you
>> want to change is technically a comment on the From: line, and not
>> the actual sender address (the bit in the <angle brackets>) all the
>> address rewriting-fu in sendmail won't really help. Besides, root@...=
>> is listed as a member of the 'Exposed User' class: that is, addresses
>> that should be exempt from address rewriting, so you'ld also have to
>> modify that.
>>
>> Do you control the mail server where you read your e-mail? Can you us=
e
>> eg. procmail(1) as a delivery agent? You should be able to match e-ma=
ils
>> from Cron and rewrite headers, or deliver cron e-mails into per-machin=
e
>> mailboxes. Something like this:
>>
>> :0 h
>> * From:.*Cron <root@\/[^\.]+
>> $MATCH
>>
>> The other alternative is to re-write the cron scripts to send e-mail
>> themselves, rather than relying on cron(8) to capture their stdout/std=
err
>> and e-mail it for you. Here's a handy shell programming trick that ca=
n
>> make that easier. Somewhere near the top of the script, you can add
>> something like this:
>>
>> exec 2>&1 | /usr/sbin/sendmail -oi -t
>> echo "From: Sender Name <sender@add.ress>
>> echo "To: <recipient@some.where>
>> echo "Subject: e-mail from cron job"
>> echo ""
>>
>> Then everything you print out in the script will be captured as the bo=
dy
>> of the e-mail and sent to the specified recipient. You might get some=
>> warnings about forgery in the mail headers if the userid the script ru=
ns
>> as is not the same as the 'From:' address.
>>
>=20
> Why not just echo `hostname` as the first line of every script? Isn't =
> that what he really wants to know?
>=20
> Or echo "This script came from `hostname`"?
There is that, but I had assumed the idea was to be able to better
distinguish the different e-mails /before/ opening them up in the
MUA.
Cheers,
Matthew
--=20
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
Kent, CT11 9PW
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