[Linux] Scripting with xfce4-panel's "Generic Monitor" applet

[griimnak]

Scripting on the xfce4-panel
The xfce4-panel is extremely customizable, offering a wide variety of applets and addons to satisfy the user's needs.

HOWEVER, if you truly desire to make the panel your own, the most important applet, in my opinion atleast, is the Generic Monitor applet.

All it takes is minutes of basic scripting knowledge to transform your panel with this simple applet.

Here's an example using my setup:

​

Tutorial
Starting with a brand new panel:

Click → + (Add new item to panel)
Search → "Generic Monitor"
Click → Add

Spoiler: Added to panel

You should now see the default text for the applet on your bar (genmon)XXX
Right-click → "(genmon)XXX" → Select "Properties"

Now the magic happens.
For starters, you can try simple shell commands such as uname -r.
These less complex commands such as uname -r may be ran without the creation of an external shell script.

Spoiler: Output of uname -r:

Now let's increase the complexity.

We need a place to store our more complex scripts, I'm going to choose a directory called ~/.genmonscripts, you can use any location and name you wish as long as it's accessible to your linux user.

mkdir ~/.genmonscripts && cd ~/.genmonscripts
touch freemem.sh

The main idea is to perform your work in the script and finally echo or print out the string you wish to display on the xfce4-panel.
freemem.sh:

#!/bin/bash
# create variable FREE_MEM, then pipe data from free -h into awk which selects the part of the text you would want
FREE_MEM=`free -h | awk '/^Mem:/ {print $3 "/" $2}'`
echo "ram $FREE_MEM  "
# printed out to panel

Once you have the script written, we can test if it works on our panel.
Note: the ~ alias will not work, you must use the real path. (typically /home/yourusername/)

sh /home/griimnak/.genmonscripts/freemem.sh

(don't forget sh at the beginning)

And that's basically it!
This may seem simple, but someone with advanced scripting knowledge could do some really impressive things with this applet.
For example, you could write a script that checks how many new emails you have, etc.

Linting your scripts
Linting your scripts are just generally considered good practice and minimize memory leaks from inefficient or invalid scripts.

Download and install

You must be registered for see links

You must be registered for see links

is a static linting tool for shell scripts.
Installation guide:

You must be registered for see links

My scripts
To assist you further with understanding how to write scripts for genmon, i'll be providing the scripts i personally use.

name: cputemp.sh
desc: returns the temp of the cpu package
useage: sh cputemp.sh

#!/bin/bash


if which sensors > /dev/null; then
    sensors | grep Core | awk '{print $3;}' | grep -oEi '[0-9]+.[0-9]+' | awk '{total+=$1; count+=1} END {print total/count,"C  "}'
else
    "??"
fi

name: sysload.sh
desc: returns both current cpu usage % and used ram/maxram ratio in one string.
usage: sh sysload.sh

#!/bin/bash
CPU=`eval $(awk '/^cpu /{print "previdle=" $5 "; prevtotal=" $2+$3+$4+$5 }' /proc/stat); sleep 0.4; eval $(awk '/^cpu /{print "idle=" $5 "; total=" $2+$3+$4+$5 }' /proc/stat); intervaltotal=$((total-${prevtotal:-0})); echo "$((100*( (intervaltotal) - ($idle-${previdle:-0}) ) / (intervaltotal) ))"`
FREE_MEM=`free -h | awk '/^Mem:/ {print $3 "/" $2}'`
printf "cpu %.f%%  " $CPU
echo "ram $FREE_MEM  "

name: netload.sh
desc: returns current network usage (up and down)
usage: sh netload.sh <adapter>
Note: Set update interval to 1.6 or above on genmon

#!/bin/bash


if [ -z "$1" ]; then
    echo
    echo usage: $0 network-interface
    echo
    echo e.g. $0 eth0
    echo
    exit
fi

IF=$1

R1=`cat /sys/class/net/$1/statistics/rx_bytes`
T1=`cat /sys/class/net/$1/statistics/tx_bytes`
sleep 1
R2=`cat /sys/class/net/$1/statistics/rx_bytes`
T2=`cat /sys/class/net/$1/statistics/tx_bytes`
TBPS=`expr $T2 - $T1`
RBPS=`expr $R2 - $R1`
TKBPS=`expr $TBPS / 1024`
RKBPS=`expr $RBPS / 1024`
printf "%s: ↓%dK ↑%dK  " $1 $RKBPS $TKBPS

Hopefully this was useful to someone out there, Happy scripting!

 

[Ecko]

you should use shellcheck

 

[griimnak]

you should use shellcheck

Seems pretty cool, basically linting for shell scripts?
Thanks for the suggestion, never knew of it until now

update: Added "Linting your scripts" section to original post.