How to get the balance of a wallet using only bash interface?
you can do it by using blockchain.info and common bash tools that you already have in your system like wget, grep and awk, printf for formatting

For example by using (replace ADDRESS with the actual address you want to query):

wget -qO- blockchain.info/rawaddr/ADDRESS 2&gt;&amp;1 | grep -Po '"final_balance":\K[0-9]+'


And if you want to format the output from satoshi to btc you can use:

wget -qO- blockchain.info/rawaddr/ADDRESS 2&gt;&amp;1 | grep -Po '"final_balance":\K[0-9]+' | awk '{s=$1/100000000} END {printf "%0.8f\n", s}'