Sending a mail from a linux shell script

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 protected] <<< "message"

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

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).

Another option for in a bash script:

mailbody="Testmail via bash script"
echo "From: [email protected]" > /tmp/mailtest
echo "To: [email protected]" >> /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.

If the server is well configured, eg it has an up and running MTA, you can just use the mail command.

For instance, to send the content of a file, you can do this:

$ cat /path/to/file | mail -s "your subject" [email protected]

man mail for more details.