pure shell naive version of a picker like fzf (without the filtering, but only picking by number)

fzf.sh

# fzf is either fzf or a naive version of it
# the input is a sed line number, so it can be 
# single number: 42
# range: 1,10
# separate lines: 10p;50p
mute command -v fzf ||
  fzf() {
    local in=$(cat)
    for p in "${@}"; do
      [ "$p" = "-0" ] && [ "$(echo "$in" | wc -l)" -eq 1 ] && [ ""  = "$in" ] && return 1
      [ "$p" = "-1" ] && [ "$(echo "$in" | wc -l)" -eq 1 ] && [ "" != "$in" ] && echo "$in" && return
    done
    # https://superuser.com/questions/1748550/read-from-stdin-while-piping-to-next-command
    cat -n <(echo "$in") >/dev/tty
    read -n num </dev/tty
    echo "$in" | sed -n "${num}p"
  }