I am using Gentoo with XFce desktop environment. I would like to get notified each time a new USB storage is attached/removed. I am sure that there exists applets/plugins that do that but I would like it to keep it simple. What could be simpler than a bash script that you can write by your self?

So I came up with the following solution:

• write a simple bash script (eg: monitor_usb-storage) which will check every 5 seconds if a new scsi/usv-storage have been attached and was registered in the /proc, and if it does then a notify balloon will be shown. The same thing when the device is removed.
• set up that script to be automatically launched at session start-up

Monitor usb storage - a working solution

How my script looks like:

#!/bin/bash
FREQ=5
PATH=/proc/scsi/usb-storage
ICON_RES="scalable"
ICON_EXT=".svg"

declare -a usb_storage
declare -a usb_storage_desc
declare -a usb_storage_dev

function get_desc()
{
	/bin/cat /proc/scsi/scsi |/usr/bin/awk -v id="scsi$1" '{i=index($0,id); if (i>0) {getline t; print t}}'
}

function get_dev()
{
	dir=/sys/bus/scsi/devices/$1:0:0:0/block
	if [ -d $dir ];then
		/bin/ls $dir
	fi
}

function init()
{
	if [ -d $PATH ];then
        	for d in $(/bin/ls $PATH);do
                	usb_storage=("${usb_storage[@]}" "$d")
			info=$(get_desc $d)
                	usb_storage_desc=("${usb_storage_desc[@]}" "$info")
			dev=$(get_dev $d)
			usb_storage_dev=("${usb_storage_dev[@]}" "$dev")
        	done
	fi
}

function item_exists()
{
	result=0
	for item in "${usb_storage[@]}";do
		if [ "$item" = "$1" ];then
			result=1
			break
		fi
	done
	echo $result
}

# initialize the usb_storage array with all existent usb-storage
init

while :;do
    # scan /proc/scsi/usb-storage for newly attached USB storage devices
    if [ -d $PATH ];then 
	for d in $(/bin/ls $PATH);do
		exists=$(item_exists $d)
		if [ "$exists" = "0" ];then
			info=$(/bin/cat $PATH/$d|/usr/bin/awk '{sub(/^[ \t]+/,"");print}')
			desc=$(get_desc $d)
			dev=$(get_dev $d)
			usb_storage=("${usb_storage[@]}" "$d")
			usb_storage_desc=("${usb_storage_desc[@]}" "$desc")
			usb_storage_dev=("${usb_storage_dev[@]}" "$dev")
			/usr/bin/notify-send -i "/usr/share/icons/Tango/${ICON_RES}/devices/usbpendrive_unmount${ICON_EXT}" "USB storage attached" "$info"
		fi
	done
    fi

    let i=0

    # check usb_storage array if contains items which does not exists any more in /proc/scsi/usb-storage (aka USB removed)
    while [ ${#usb_storage[@]} -gt 0 -a $i -lt  ${#usb_storage[@]} ];do # loop from 0 to end of array
	item=${usb_storage[$i]}
	if [ ! -e $PATH/$item ];then # if array item not exist on PATH
		/usr/bin/notify-send -i "/usr/share/icons/Tango/${ICON_RES}/devices/usbpendrive_unmount${ICON_EXT}" "USB storage removed (${usb_storage_dev[$i]})" "${usb_storage_desc[$i]}"
		unset usb_storage[$i]
		unset usb_storage_desc[$i]
		unset usb_storage_dev[$i]
	else
		let i=$i+1
	fi
    done

    # sleep about 5 seconds (we don't want to scan too agressive)
    /usr/bin/sleep $FREQ
done

Start monitor_usb-storage as daemon at session start-up

In Xfce you can set up a Application Autostart (which are supposed to start at session start up):

• Settings -> Session and Startup -> Application Autostart tab
• define a new application autostart as bellow:
  • name: monitor_usb-storage (in fact it doesn't matter how you will name it)
  • command: monitor_usb-storage

So, the daemon will start when your X session starts and then will monitor the new usb-storage attached/removed every 5 seconds. When new device attached/removed then a balloon notification like the one bellow will be shown:

Now, if you think that this article was interesting don't forget to rate it. It shows me that you care and thus I will continue write about these things.

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Eugen Mihailescu

Founder/programmer/one-man-show at Cubique Software

Always looking to learn more about *nix world, about the fundamental concepts of math, physics, electronics. I am also passionate about programming, database and systems administration. 16+ yrs experience in software development, designing enterprise systems, IT support and troubleshooting.

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