How to display text at the bottom of the terminal window, and make it stay there, in Bash?

Question

I am using a while loop to perform an ffmpeg operation that makes a bunch of files, and I want an indicator at the bottom of the screen that says what file I am on, that stays at the bottom of the screen, while ffmpeg is giving output. Sort of similar to how in the apt package manager, there is a progress bar that is always at the bottom, while it gives output information above it. I don't need a progress bar, just a string of text containing the file number to always be at the bottom.

A very simplified version of my code:

# Initialize file number
file_number=1

while IFS=, read -r starttime name endtime; do
    # ffmpeg command
    ffmpeg -ss $starttime_seconds -i "$1" -t $duration -codec libopus "$safename" < /dev/null

    # Display progress, this is what I want at the bottom of the screen
    echo -en "\r--- FILE $file_number ---"
    file_number=$((file_number+1))
done < "$2"

Answer 1

With tput . Replace in your code

echo -en "\r--- FILE $file_number ---"

with

print_status

and put this before your code:

LINES=$(tput lines)

set_window ()
{
    # Create a virtual window that is two lines smaller at the bottom.
    tput csr 0 $(($LINES-2))
}

print_status ()
{
    # Move cursor to last line in your screen
    tput cup $LINES 0;

    echo -n "--- FILE $file_number ---"

    # Move cursor to home position, back in virtual window
    tput cup 0 0
}

set_window

---

See: man tput and man 5 terminfo