My console program runs under Ubuntu 20.04. When run interactively, the input expression (e.g., a+b below) is displayed next to the prompt followed by the output on a new line as follows. I would like to achieve this same format when providing the input to the program from a bash script.

$ ./rec_desc1
Enter expression: a+b
F --> id
R --> eps
T --> FR
F --> id
R --> eps
T --> FR
Q --> eps
Q --> +TQ
E --> TQ
Success. 

But if I send the input from a bash script via here-string or piping it (as suggested at How do I provide input to a C program from bash?), the input is not displayed and unfortunately the first line of output is shifted up next to prompt as shown below.

cat rec_desc1_unit_test
#!/bin/bash
echo "Test case 1"
./rec_desc1 <<< a+b

$ ./rec_desc1_unit_test
Test case 1
Enter expression: F --> id
R --> eps
T --> FR
F --> id
R --> eps
T --> FR
Q --> eps
Q --> +TQ
E --> TQ
Success. 

Is there a way to pass the input from a bash script so that it displays next to the prompt and is followed by a newline so it matches the interactive case above?

I eventually want to run numerous test cases for different expressions from a bash script and would like to have the self-documentation of the input expression being displayed. I could call set -v prior to invoking the console program in order to display the input if necessary (as shown below). Then I would need to call set +v immediately afterward to avoid displaying the echo statements that describe the next test case. I would like to avoid surrounding each test case with set -v and set +v if possible.

$ cat rec_desc1_unit_test
#!/bin/bash
echo "Test case 1"
set -v
./rec_desc1 <<< a+b

$ ./rec_desc1_unit_test
Test case 1
./rec_desc1 <<< a+b
Enter expression: F --> id
R --> eps
T --> FR
F --> id
R --> eps
T --> FR
Q --> eps
Q --> +TQ
E --> TQ
Success.