Ubuntu/Scripts

Revision as of 12:54, 23 June 2014

Email current IP address

Variables needing to be defined:

• sender domain (@sennder domain.com)
• recipient (recipient address)
• recipient mail exchanger (recipient mail exchanger)

Variables automatically defined

• HOSTNAME - defined by using the hostname command
• DATE - defined by using the date command
• IP - queries checkip.dyndns.org and then parses the return to exclude everything except the IP address
• UPTIME - defined by using the uptime command
• USERS - defined by using the users command

Code

#!/bin/bash -x

#define variables
HOSTNAME=$(hostname)
from="$HOSTNAME"'@sender domain.com'
to='recipient address'
recipient_mx='recipient mail exchanger'
DATE=$(date)
messageid='[email protected]'
IP=$(curl checkip.dyndns.org|awk '/Address:/ {print$6}'|sed 's/<.*/ /')
UPTIME=$(uptime)
USERS=$(users)

#function containing mail commands.  Contains enough RFC required fields to satisfy gmail's requirements to allow the message, though it may be detected as spam if you do not have a SPF record.
function mail_input {
        sleep 1
        echo 'ehlo test.com\n'
        sleep 0.5
        printf 'mail from:<'"$from"'>\n'
        sleep 1
        printf 'rcpt to:<'"$to"'>\n'
        sleep 1
        printf 'data\n'
        sleep 0.5
        printf 'Return-Path: <'"$from"'>\n'
        printf 'Date: '"$DATE"'\n'
        printf 'Message-ID: <'"$messageid"'>\n'
        printf 'Subject: '"$HOSTNAME"' ip address= '"$IP"'\n'
        printf 'From: <'"$from"'>\n'
        printf 'To: <'"$to"'>\n'
        printf 'hostname='"$HOSTNAME"'\n'
        printf 'ip address= '"$IP"'\n'
        printf 'uptime= '"$UPTIME"'\n'
        printf 'users logged in= '"$USERS"'\n'
        printf '.\n'
        printf 'quit'
}

#sending mail with mail_input function
mail_input | telnet $recipient_mx 25

Learned

• you cannot define a variable as the same exact spelling of the command.

WRONG: hostname ≠ `hostname`
RIGHT: HOSTNAME = `hostname`

• you can call a standard command and define its output as a variable, so long as you use " ` " around the command (old school) or "$( )" around it

WRONG: HOSTNAME ≠ 'hostname'
RIGHT: HOSTNAME = `hostname`
RIGHT: HOSTNAME = $(hostname)

• when using printf you should be careful which type of quote to use. a single quote should be used for plain text, such as a static heading to an output. a double quote should be used for defining variables.

WRONG: printf "Address: " '$IP' "\n"
RIGHT: printf 'Address: ' "$IP" '\n'

adding -x to your #!/bin/bash statement will cause everything to be printed, useful in troubleshooting

#!/bin/bash -x