notify-send from within a bash script - bash

Question

I'd like to use notify-send from within a bash script that is running in the background to inform the user about the progress of the script. More specifically this is a script that automagically runs when a USB flash drive is inserted and runs a scan with ClamAV.
Specifically at line 30 and line 66. So far, I'm not having any luck. Can someone give me some advice/help? Thanks.
#!/bin/bash
#doOnUSBinsert_0.2.sh
#Author : Totti
# Make it executable by running 'sudo chmod x doOnUSBinsert_0.2.sh'
if ! [ -f /etc/udev/rules.d/80-doOnUSBinsert.rules ]
then # rule not added
cp "$0" /usr/bin/doOnUSBinsert
chmod u x /usr/bin/doOnUSBinsert
# echo 'SUBSYSTEM=="usb", ACTION=="add", RUN ="/path/to/script.sh"' | sudo tee /etc/udev/rules.d/80-clamscan.rules
echo 'SUBSYSTEM=="usb", ACTION=="add", RUN ="/usr/bin/doOnUSBinsert & "' | tee /etc/udev/rules.d/80-doOnUSBinsert.rules
if [ $? -eq 0 ]
then
echo 'Rule Successfully added. See file "/usr/bin/doOnUSBinsert" if you wish to edit the command'
exit 0
else
echo 'ERROR while adding rule'
exit 1
fi
fi
lfile="/tmp/doOnUSBinsert.log" # udev
lfile2="/tmp/clamscanFromUdev.log" # clamscan
lfile3="/tmp/doOnUSBinsert_mount.log" # mount
notify-send "USB SCAN ON INSERT" "Currently scanning with ClamAV"
main ()
{
sleep 12 # let the partitions to mount
#cat /proc/$$/environ | tr '�' 'n' >> /tmp/udevEnvirn.txt
echo "found $ID_SERIAL" >> "$lfile"
cat /etc/mtab | grep "^$part_c" >> "$lfile.3"
if [ "$ID_SERIAL"x = 'x' ]
then
echo "Exiting on empty ID_SERIAL" >> "$lfile"
exit 1
fi
#Eg: ID_SERIAL --> /dev/disk/by-id/usb-sandisk....42343254343543
#i=0
echo 'searching partitions' >> "$lfile"
for partitionPath in $( find /dev/disk/by-id/ -name "*$ID_SERIAL*part*" )
do
echo "current partition = $partitionPath" >> "$lfile"
# part[i ]="$( readlink -f "$partition" )" # Eg Output: /dev/sdb1 , /dev/sdb2
part_c="$( readlink -f $partitionPath )"
mpoint="$( cat /etc/mtab | grep "^$part_c" | awk '{print $2}' )"
echo "partitionPath= $partitionPath, part = $part_c, mountpoint= $mpoint" >> "$lfile"
echo "Scaning --> $mpoint" >> "$lfile.2"
############################################
clamscan -r --bell "$mpoint"/* >> "$lfile.2"
#############################################
done
}
notify-send "USB SCAN ON INSERT" "Finished scanning with ClamAV"
main &
echo ______________________________________ >> "$lfile"
exit 0

Answer 1

I'm pretty new to the linux world, but while looking for a solution for a similar project I found THIS
Tip: An overview on the available icons can be found here. To send
desktop notification from a background script running as root (replace
X_user and X_userid with the user and userid running X respectively):
sudo -u X_user DISPLAY=:0 DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/X_userid/bus notify-send 'Hello world!' 'This is an example notification.'
Hope this will help others.

Answer 2

Depending on how you are running the script it may not have access to the display variable. Try running export DISPLAY=:0.0 prior to the command.
If you are running the script as a different user, ie root, then you may also need to run it as su - <logged in user> -c notify-send ... (I usually don't need to do this, but I remember having to at one point - but I cant recall which distro or version I was on at the time.)