Sending a mail from a linux shell script

问题:

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?

回答1:

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" [e-mail]

man mail for more details.

回答2:

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" [e-mail] <<< "message"

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

回答3:

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).

回答4:

Generally, you'd want to use mail command to send your message using local MTA (that will either deliver it using SMTP to the destination or just forward it into some more powerful SMTP server, for example, at your ISP). If you don't have a local MTA (although it's a bit unusual for a UNIX-like system to omit one), you can either use some minimalistic MTA like ssmtp.

ssmtp is quite easy to configure. Basically, you'll just need to specify where your provider's SMTP server is:

# The place where the mail goes. The actual machine name is required
# no MX records are consulted. Commonly mailhosts are named mail.domain.com
# The example will fit if you are in domain.com and you mailhub is so named.
mailhub=mail

Another option is to use one of myriads scripts that just connect to SMTP server directly and try to post a message there, such as Smtp-Auth-Email-Script, smtp-cli, SendEmail, etc.

回答5:

Another option for in a bash script:

mailbody="Testmail via bash script"
echo "From: [e-mail]" > /tmp/mailtest
echo "To: [e-mail]" >> /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.

回答6:

Admitting you want to use some smtp server, you can do:

export SUBJECT=some_subject
export smtp=somehost:someport
export EMAIL=someaccount@somedomain
echo "some message" | mailx -s "$SUBJECT" "$EMAIL"

Change somehost, someport, and someaccount@somedomain to actual values that you would use. No encryption and no authentication is performed in this example.

回答7:

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

回答8:

On linux, mail utility can be used to send attachment with option "-a". Go through man pages to read about the option. For eg following code will send an attachment :

mail -s "THIS IS SUBJECT" -a attachment.txt [e-mail] <<< "Hi Buddy, Please find failure reports."

回答9:

The mail command does that (who would have guessed ;-). Open your shell and enter man mail to get the manual page for the mail command for all the options available.