Sending Mail from bash script to application

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#1

Dear all,
I have been suggested to open a new thread on how to send mails to internet addresses.

My script is using mail to report problems coming from a backup script. The idea is to get an email when a problem happens or when backup finishes succesfully.

This is how my code looks like concerning the usage of mail



#!/bin/bash

# The scripts should always start with the external devices unmounte.
# 1. First checks that the device is not mounted (that should be always)
# 2. Mounts the device
# 3. Copy the files
# 4. Unmounts the device
# 5. Send emails at the moment a failure appears or at the end when everything was succesful


SCRIPTNAME="BACKUPOFDATA.SH"
MOUNTPOINT=/mnt/BckpMeasurements
MAILADDRESS="hidden@hidden.com"

# 1.
MOUNT=`mount | grep $MOUNTPOINT`
if ! test -n "$MOUNT" ; then
        #2.
        mount $MOUNTPOINT 
        # In case the above did not work. I need to send email with message and stop immediately. How I check that the mount was done?
else
        echo "Device already mounted! Why? Check if something wrong happened with the backup scripts" | mail -r \
                                $MAILADDRESS -s "Backup Scripts Failed" $MAILADDRESS
        exit

fi

# Do the Copy of The Files

# 3.
# rsync command goes here
# if rsync failes send an email to me too

# How to check that rsync returned succesfully
# End of Copy of the files


# 4.
# Unmount the Device
umount $MOUNTPOINT
MOUNT=`mount | grep $MOUNTPOINT`
if  test -n "$MOUNT" ; then
        echo "Device Failed to be unmounted! Why? Check if something wrong happened with the backup scripts" | mail -r \
                                $MAILADDRESS -s "Backup Scripts Failed" $MAILADDRESS
        exit
fi


# I want to send me also an email with backup sucessful
# That should be when rsync returned succesfully and the unmount was too.

# 5.
echo "Script Name: Data and Time. Rsync finished successfully. Device was also unmounted Successfully. Send a kiss to robin_lista" | mail -r \
                                $MAILADDRESS -s "Backup Scripts Finished at" $MAILADDRESS
#2

On 2013-03-11 08:26, alaios wrote:
>
> Dear all,
> I have been ‘suggested’ (http://tinyurl.com/cs3lh2k) to open a new
> thread on how to send mails to internet addresses.
>
> My script is using mail to report problems coming from a backup script.
> The idea is to get an email when a problem happens or when backup
> finishes succesfully.
>
>
> This is how my code looks like concerning the usage of mail

The only thing we need to know is is this:


>   #!/bin/bash
>

>   MAILADDRESS="hidden@hidden.com"

>   mail -r $MAILADDRESS -s "Backup Scripts Failed" $MAILADDRESS

Notice that the “From” address and the “To” address are exactly the
same. So what we need to know now is what happens. Me, I would think it
will fail because you have no mail body, so ‘mail’ would probably enter
into interactive mode for you to type the body. The body should instead
attached with a pipe from a text file " < body.txt".

So what happens? If you do not know, look at the email log :slight_smile:

–
Cheers / Saludos,

Carlos E. R.
(from 11.4, with Evergreen, x86_64 “Celadon” (Minas Tirith))

#3

It is legal (i.e. allowed) for mail to have an empty body.

#4

> It is legal (i.e. allowed) for mail to have an empty body.

Yes, or at least empty to humans. Sending mail this way is pretty common:

mail -s ‘subject goes here’ ab@no-mx.forums.novell.com < /dev/null

Google found several hits and this one specifically shows some good examples:

http://www.cyberciti.biz/faq/linux-unix-bash-ksh-csh-sendingfiles-mail-attachments/

Good luck.

#5

On 2013-03-11 15:06, nrickert wrote:
>
> robin_listas;2533713 Wrote:
>> Me, I would think it
>> will fail because you have no mail body, so ‘mail’ would probably enter
>> into interactive mode for you to type the body.
> It is legal (i.e. allowed) for mail to have an empty body.

Yes, of course, as long as the mail command allows for it. See ‘ab’
response, how he does a dev/null redirect.

–
Cheers / Saludos,

Carlos E. R.
(from 11.4, with Evergreen, x86_64 “Celadon” (Minas Tirith))

#6

Hi,
concerning security issues. I am using postfix, at least this is what I think mail command uses to send emails. My firewall is enabled and the only enables port is the ssh port.

Is that enough for keeping outsiders?

Regards
Alex

#7

Looks to me should work.

Besides your script,
Make sure you have Postfix or Sendmail installed, default configuration should permit senind only from your local machine. No FW setting is required for protection.

Secure your script so it cannot be invoked by anything but what you need configuring permissions.
Secure your script so it’s not publicly visible.

Most public mailservers today are configured to block messages from any but those with DNS reverse lookup records. For that reason although you’re running a local SMTP server, you will likely need to still route through an authorized Smart SMTP relay unless you’re sending to a private mailserver you own that you can configure.

HTH,
TSU

#8

With regard to mail unless you reconfigure Postfix to listen on all
addresses and open TCP 25 (or another relevant port for Postfix) in the
firewall it should be pretty tricky for somebody to do anything bad to
this box. You’re just sending, not receiving. Even legitimate folks
trying to reply to these e-mails you send from the command line will
probably fail unless your DNS mail server handles this sender’s address
for you.

Good luck.

#9

On 2013-03-12 19:36, tsu2 wrote:

> Most public mailservers today are configured to block messages from any
> but those with DNS reverse lookup records. For that reason although
> you’re running a local SMTP server, you will likely need to still route
> through an authorized Smart SMTP relay unless you’re sending to a
> private mailserver you own that you can configure.

Yes, that’s the tricky part.

For example, I teach my postfix to know that when I send an email with a
gmail “from” address it has to contact gmail with the proper
login/password to rely my email to its destination - the same as if I
were using kmail or thunderbird to send email.

I can explain that another day. I have to travel tomorrow and I also
have a toothache, so I don’t feel inclined to write a lot till the
dentist does his job (argh!). In fact, I’m waiting for the analgesic to
make effect and I go to sleep.

Or you may have an ISP that accepts you send through them all your
emails. This is the traditional rely setup. I have never seen such an
ISP, though: I have to use a separate login/pass for each from address.
Postfix supports both modes.

Postfix is, of course, perfectly capable of sending any email directly
to the destination without help from any other server, but… but no
destination will accept those emails any longer. Not unless you have a
properly registered and configured domain (with a fixed address). Your
email will be rejected, you will not manage to connect, etc.

Another method is to configure the program ‘mail’ (aka ‘mailx’) to use
an external SMTP server and identify to it. I have never done this, but
it is documented in its manual page. This is basically the same most
people do with thunderbird, evolution, kmail…

–
Cheers / Saludos,

Carlos E. R.
(from 11.4, with Evergreen, x86_64 “Celadon” (Minas Tirith))