Get the last non-empty string from a file using shellscript

Question

I wrote the following code:

success="Traffic Engineering Tunnel validated successfully"
text=$(tail -2 /apps/pofitb/logs/tunnels.log)
echo $executed_date
if  [[ $text = $success ]]
then
    text=$(tail -2 /apps/pofitb/logs/tunnels.log)
    echo "Tunnel script execution is successful" | mailx -s "Tunnel script is executed succefsfully on $executed_date" abc@gmail.com 
else
    echo "Tunnel script  lastly executed  on $executed_date" | mailx -s "Tunnel script  FAILED!!!" abc@gmail.com 
fi
exit

Currently tunnel.log file has blank line while being updated. So, text=$(tail -2 /apps/pofitb/logs/tunnels.log) extracts the last non-blank line from the end of the file. This works if the number of blank line inserted at the end of the file is 1.

How can I modify the script such that the script searches for the last last non-blank line from the file tunnel.log, irrespective of the number of blank lines inserted ?

Answer 1

awk to the rescue!

tac log | awk 'NF{print;exit}'

if your log is too long, start with a generous tail first

 tail -5 log | tac | awk 'NF{print;exit}'

will print the last non-empty line.