#!/bin/bash

while true
do
state=`cat /proc/acpi/battery/BAT1/state`
if [[ "$state" == "whatever" ]];
then
echo "email" |mail -s "dhsudia" me@email
else
fi
done

# -----------------------------------------------------------------------------------------------------------------------------------------------------

#!/bin/bash

# This will only do something if the state changes, and never exit. Start this in the background after adding your own actions for the change events


last_state=`cat /proc/acpi/battery/BAT1/state`
echo "current_state: $last_state"

while true
do
state=`cat /proc/acpi/battery/BAT1/state`
if [[ "$state" == "$last_state" ]];
then
    echo "state not changed don't do anything"
else
    echo "state changed to $last_state , do something"
    
    last_state=`echo $state`
fi

sleep 5
done

# -----------------------------------------------------------------------------------------------------------------------------------------------------


#!/bin/bash
     
#store current state on start
last_state=`cat /proc/acpi/battery/BAT1/state`

#lets write it to console
echo "current_state: $last_state"
     
#keep looking for changes using an infinite loop

while true
do

 state=`cat /proc/acpi/battery/BAT1/state`
 if [[ "$state" == "$last_state" ]];
 then
    echo "state not changed don't do anything"
 else
    echo "state changed to $state , do something now"
    #update last state
    last_state=`echo $state`
 fi
#just wait a little to avoid high cpu load
sleep 5
done


# -----------------------------------------------------------------------------------------------------------------------------------------------------


cp /etc/pam_ldap.conf{,.old}

# or even better:

cp /etc/pam_ldap.conf{,.$(date +%F)}