Create a variable from another variable in shell script

Question

In a shell script I will store the output as a variable like below

Test=$(/home/$USER/import.py $table)

Now this Test variable will have more than 2 lines like below

table= 123_test
min_id=1
max_id=100
123_test,1,100

Now I want to store the last line of the Test variable as another variable called output .

I have tried like below. But not getting the desired result

output=`$test | tail -n 1`

Can we create a variable from another variable in a shell script. If yes, How can we do that?

Answer 1

Use echo to pipe the variable to the other command.

output=$(echo "$test" | tail -1)

or a here-string:

output=$(tail -1 <<<"$test")

Don't forget to quote the variable in both cases, otherwise all the lines will be combined.

Finally, you can use a parameter expansion operator to select the last line, instead of using tail :

output=${test##*$'\n'}