I used to use `unbuffer` which comes with expect, and might be what you used too. I now use the following hack, which works faster:

Create isatty.so like this:

    echo "int isatty(int fd) { return 1; }" | gcc -O2 -fpic -shared -ldl -o isatty.so -xc -

Then to make `some_program` think it's in a tty:

    LD_PRELOAD=./isatty.so some_programe

Source and more: https://unix.stackexchange.com/questions/249723/how-to-trick...