export maillist=abc@gmail.com;
#df -PH /d04 /d05 /u01 /export | grep -vE '^Filesystem|none|cdrom'|awk '{ print $5 " " $6 }' | while read output;
df -PH | grep -vE '^Filesystem|none|cdrom|swdepot'|awk '{ print $5 " " $6 }' > $HOME/monitor/diskcheck.log;

if [ -s "$HOME/monitor/log/disk_alert.log" ]; then
#Getting variables and compare with old
  usep=($(awk '{ print $1 }' $HOME/monitor/diskcheck.log | cut -d'%' -f1));
  partitions=($(awk '{ print $2 }' $HOME/monitor/diskcheck.log | cut -d'%' -f1));
  usep1=($(awk '{ print $1 }' $HOME/monitor/log/disk_alert.log | cut -d'%' -f1));
else
   cat "$HOME/monitor/diskcheck.log" > "$HOME/monitor/log/disk_alert.log";
  usep=($(awk '{ print $1 }' $HOME/monitor/diskcheck.log | cut -d'%' -f1));
  partitions=($(awk '{ print $2 }' $HOME/monitor/diskcheck.log | cut -d'%' -f1));
  usep1=($(awk '{ print $1 }' $HOME/monitor/log/disk_alert.log | cut -d'%' -f1));
fi

echo ${usep[@]};
echo ${usep1[@]};
unset alertlist
# index = i
for i in ${!usep[@]}; do
        if [ ${usep[$i]} -gt 80 ]; then
                if [ ${usep[$i]} -gt ${usep1[$i]} ]; then
                        # Temp to store current percentage diff and partition to store in a variable.
                        tmp="$(echo -e "Running out of space \"${partitions[$i]} (${usep[$i]}%)\" on $(hostname) as on $(date)")";
                        echo "$tmp"
                        #tmp=$(printf "%s\n" "(${usep[$i]}%) percent used on ${partitions[$i]}");
                        alertlist=("${alertlist[@]}" "$tmp")
                fi
        fi
done

if [ ${#alertlist} -gt 0 ]; then
        printf '%s\n' "${alertlist[@]}" | mail -s "ALERT:  Running out of space" $maillist;
        echo "Following text sent as body of mail to $maillist:"
        printf '%s\n' "${alertlist[@]}"
fi                     #alertlist holds the values to send mail.

[vijay@localhost monitor]$ sh disk_alert.sh
19 1 39 3 40 93 1 14 96
19 1 39 3 40 83 1 14 66
Running out of space "/u05 (93%)" on localhost.local as on Tue May 16 
Running out of space "/u02 (96%)" on localhost.local as on Tue May 16 
Following text sent as body of mail to abc@gmail.com:
Running out of space "/u05 (93%)" on localhost.local as on Tue May 16 
Running out of space "/u02 (96%)" on localhost.local as on Tue May 16

Running out of space "/u05 (93%)" on localhost.local as on Tue May 16 Running out of space "/u02 (96%)" on localhost.local as on Tue May 16