Length of Bash prompt PS1

sudo apt install ansi2txt
printf "${PS1@P}" | ansi2txt | col | wc -m

Print a line of A's and 🐧's

Number of terminal cols

tput cols

Fill terminal line with A.

printf "\x41" | xargs yes 2>/dev/null | head -n $(tput cols) | tr -d "\n" | xargs printf "%s\n"

Fill terminal line with penguin.

printf "\U1F427" | xargs yes 2>/dev/null | head -n $(($(tput cols)/2)) | tr -d "\n" | xargs printf "%s\n"

printf "\x41" | xargs yes 2>/dev/null | head -n $(tput cols) | tr -d "\n" &&
printf "\U1F427" | xargs yes 2>/dev/null | head -n $(($(tput cols)/2)) | tr -d "\n" | xargs printf "%s\n"