Sending a mail from a linux shell script

Question

I want to send an email from a Linux Shell script. What is the standard command to do this and do I need to set up any special server names?

Answer 1

SEND MAIL FROM LINUX TO GMAIL

USING POSTFIX

1: install software

Debian and Ubuntu:

apt-get update && apt-get install postfix mailutils

OpenSUSE:

zypper update && zypper install postfix mailx cyrus-sasl

Fedora:

dnf update && dnf install postfix mailx

CentOS:

yum update && yum install postfix mailx cyrus-sasl cyrus-sasl-plain

Arch Linux:

pacman -Sy postfix mailutils

FreeBSD:

portsnap fetch extract update

cd /usr/ports/mail/postfix

make config

in configaration select SASL support

make install clean

pkg install mailx

2. Configure Gmail

/etc/postfix. Create or edit the password file:

vim /etc/postfix/sasl_passwd

i m using vim u can use any file editer like nano, cat .....

>Ubuntu, Fedora, CentOS,Debian, OpenSUSE, Arch Linux:

add this

where user replace with your mailname and password is your gmail password

[smtp.gmail.com]:587    user@gmail.com:password

Save and close the file and Make it accessible only by root: becouse its an sensitive content which contains ur password

chmod 600 /usr/local/etc/postfix/sasl_passwd

>FreeBSD:

directory /usr/local/etc/postfix.

vim /usr/local/etc/postfix/sasl_passwd

Add the line:

[smtp.gmail.com]:587    user@gmail.com:password

Save and Make it accessible only by root:

chmod 600 /usr/local/etc/postfix/sasl_passwd

3. Postfix configuration

configuration file main.cf

6 parameters we must set in the Postfix

Ubuntu, Arch Linux,Debian:

edit

 vim /etc/postfix/main.cf

modify the following values:

relayhost = [smtp.gmail.com]:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options =
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

smtp_sasl_security_options which in configuration will be set to empty, to ensure that no Gmail-incompatible security options are used.

save and close

as like for

OpenSUSE:

vim /etc/postfix/main.cf

modify

relayhost = [smtp.gmail.com]:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options =
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/ssl/ca-bundle.pem

it also requires configuration of file master.cf

modify:

vim /etc/postfix/master.cf

as by uncommenting this line(remove #)

#tlsmgr unix - - n 1000? 1 tlsmg

save and close

Fedora, CentOS:

vim /etc/postfix/main.cf

modify

relayhost = [smtp.gmail.com]:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options =
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/ssl/certs/ca-bundle.crt

FreeBSD:

vim /usr/local/etc/postfix/main.cf

modify:

relayhost = [smtp.gmail.com]:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options =
smtp_sasl_password_maps = hash:/usr/local/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/mail/certs/cacert.pem

save and close this

4. Process Password File:

Ubuntu, Fedora, CentOS, OpenSUSE, Arch Linux,Debian:

postmap /etc/postfix/sasl_passwd

for freeBSD

postmap /usr/local/etc/postfix/sasl_passwd

4.1) Restart postfix

Ubuntu, Fedora, CentOS, OpenSUSE, Arch Linux,Debian:

systemctl restart postfix.service

for FreeBSD:

service postfix onestart
nano /etc/rc.conf

add

postfix_enable=YES

save then run to start

service postfix start

5. Enable "Less Secure Apps" In Gmail using help of below link

https://support.google.com/accounts/answer/6010255

6. Send A Test Email

mail -s "subject" recever@domain.com

press enter

add body of mail as your wish press enter then press ctrl+d for proper termination

if it not working check the all steps again and check if u enable "less secure app" in your gmail

then restart postfix if u modify anything in that

for shell script create the .sh file and add 6 step command as your requirement

for example just for a sample

#!/bin/bash
REALVALUE=$(df / | grep / | awk '{ print $5}' | sed 's/%//g')
THRESHOLD=80

if [ "$REALVALUE" -gt "$THRESHOLD" ] ; then
    mail -s 'Disk Space Alert' mailid@domainname.com << EOF
Your root partition remaining free space is critically low. Used: $REALVALUE%
EOF
fi

The script sends an email when the disk usage rises above the percentage specified by the THRESHOLD varialbe (80% here).

Answer 2

If both exim and ssmtp are running, you may enter into troubles. So if you just want to run a simple MTA, just to have a simple smtp client to send email notifications for insistance, you shall purge the eventually preinstalled MTA like exim or postfix first and reinstall ssmtp.

Then it's quite straight forward, configuring only 2 files (revaliases and ssmtp.conf) - See ssmtp doc - , and usage in your bash or bourne script is like :

#!/bin/sh  
SUBJECT=$1  
RECEIVER=$2  
TEXT=$3  

SERVER_NAME=$HOSTNAME  
SENDER=$(whoami)  
USER="noreply"

[[ -z $1 ]] && SUBJECT="Notification from $SENDER on server $SERVER_NAME"  
[[ -z $2 ]] && RECEIVER="another_configured_email_address"   
[[ -z $3 ]] && TEXT="no text content"  

MAIL_TXT="Subject: $SUBJECT\nFrom: $SENDER\nTo: $RECEIVER\n\n$TEXT"  
echo -e $MAIL_TXT | sendmail -t  
exit $?  

Obviously do not forget to open your firewall output to the smtp port (25).

Answer 3

You don't even need an MTA. The SMTP protocol is simple enough to directly write it to your SMTP server. You can even communicate over SSL/TLS if you have the OpenSSL package installed. Check this post: https://33hops.com/send-email-from-bash-shell.html

The above is an example on how to send text/html e-mails that will work out of the box. If you want to add attachments the thing can get a bit more complicated, you will need to base64 encode the binary files and embed them between boundaries. THis is a good place to start investigating: http://forums.codeguru.com/showthread.php?418377-Send-Email-w-attachments-using-SMTP

Answer 4

you can use 'email' or 'emailx' command.

(1) $ vim /etc/mail.rc # or # vim /etc/nail.rc

set from = xxx@xxx.com #
set smtp = smtp.exmail.gmail.com #gmail's smtp server 
set smtp-auth-user = xxx@xxx.com #sender's email address
set smtp-auth-password = xxxxxxx #get from gmail, not your email account passwd
set smtp-auth=login

Because if it is not sent from an authorized account, email will get to junk mail list.

(2) $ echo "Pls remember to remove unused ons topics!" | mail -s "waste topics" -a a.txt developer@xxx.com #send to group user 'developer@xxxx.com'

Answer 5

Another option for in a bash script:

mailbody="Testmail via bash script"
echo "From: info@myserver.test" > /tmp/mailtest
echo "To: john@mywebsite.test" >> /tmp/mailtest
echo "Subject: Mailtest subject" >> /tmp/mailtest
echo "" >> /tmp/mailtest
echo $mailbody >> /tmp/mailtest
cat /tmp/mailtest | /usr/sbin/sendmail -t

• The file /tmp/mailtest is overwritten everytime this script is used.
• The location of sendmail may differ per system.
• When using this in a cron script, you have to use the absolute path for the sendmail command.

Answer 6

If you want a clean and simple approach in bash, and you don't want to use cat, echo, etc., the simplest way would be:

mail -s "subject here" email@address.com <<< "message"

<<< is used to redirect standard input. It's been a part of bash for a long time.