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).