Bash Modified alert file for Raspbery Pi on Raspbian
I'm a bit new to here on Stackoverflow (which you will probably see from my reputation), but I was wondering how to make an audio alert or some other type of change to the auto-polling log file for failed login attempts for RDP sessions (in particular XRDP) on Rasbperry Pi.
Since this is a Raspberry Pi, I'm sure you can understand why I want to run it headless.
I've searched many times and seem to have found links or ways to make audible warnings when connected directly to the Pi. I want this warning to appear while running in a main silent terminal window. I would prefer a beep for new log activity (if the size of the log file has changed, beep) and then the log will be checked at regular intervals (i.e. every 30 seconds or 1 minute, etc.).
My log location is here if it helps me give me an idea on how to start doing this Bash script / var / log / xrdp.log
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Here is the gist of a bash script that will do exactly what you want, over SSH, on a Raspberry Pi (or any Linux):
https://gist.github.com/free5ty1e/300adb0800ba45f3fe4e
#!/bin/bash
# xrdpLogMonitor.sh <optional timeout in seconds>
# This script will check and spit out your xrdp log file every X seconds
# (default 30 if not specified)
# If the file size has changed since your last check, your terminal will beep (system alert)
logFileName="/var/log/xrdp.log"
if [ $# -eq 0 ];
then
echo "No arguments supplied, will use default time between log polls (30 seconds)"
secondsBetweenLogPolls=30
else
echo "Using supplied timeout of $1 seconds between log polls"
secondsBetweenLogPolls=$1
fi
function updateLogModifiedTimeAndBeepIfChanged()
{
lastLogModifiedTime=$LogModifiedTime
LogModifiedTime="$(stat --printf="%Z" $logFileName)"
if [ "$LogModifiedTime" != "$lastLogModifiedTime" ];
then
echo NEW LOG ACTIVITY CAPTURED!!!!
#Below line creates the terminal beep
echo -ne '\a'
fi
}
while [ 1 -lt 2 ]; do
updateLogModifiedTimeAndBeepIfChanged
echo "$(ls -l $logFileName)"
echo "Polling logfile $logFileName which was last modified at $LogModifiedTime..."
#You will need sudo on the pi to cat this xrdp log
sudo cat $logFileName
#Uncomment the following line to search, for example, for "USER:" and display only those lines that contain it:
#sudo cat $logFileName | grep USER:
echo "$(date) <--- this is now"
sleep $secondsBetweenLogPolls
done
Once you've created the xrdpLogMonitor.sh file, don't forget to install it as executable by typing:
chmod +x ./xrdpLogMonitor.sh
Then execute it by typing:
./xrdpLogMonitor.sh
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