Bash – Command to output to current prompt

You could use extdebug:

shopt -s extdebug
trap '
  read -n1 -p "run \"$BASH_COMMAND\"? " answer <> /dev/tty 1>&0
  echo > /dev/tty
  [[ $answer = [yY] ]]' DEBUG

cmd1
cmd2
...

For reference, the zsh equivalent would be:

TRAPDEBUG() {
  read -q "?run \"$ZSH_DEBUG_CMD\"? " || setopt errexit
  echo > /dev/tty
}
cmd1
cmd2
...

More portably:

run() {
  printf %s "run $*? " > /dev/tty
  read answer < /dev/tty
  case $answer in
    [yY]*) "$@";;
  esac
}
run cmd1
run cmd2
run cmd3 > file

Beware that in cmd3 > file, the file will be truncated even if you say n. So you may want to write it:

run eval 'cmd3 > file'

Or move the eval to the run function as in:

run() {
  printf %s "run $*? " > /dev/tty
  read answer < /dev/tty
  case $answer in
    [yY]*) eval "$@";;
  esac
}
run cmd1
run 'cmd2 "$var"'
run 'cmd3 > file'

Another portable one, but with even more limitations:

xargs -pL1 env << 'EOF'
cmd1 "some arg"
cmd2 'other arg' arg\ 2
ENV_VAR=value cmd3
EOF

It only works for commands (ones found in $PATH), and arguments can only be strings (no variable or any shell structure, though xargs understand some forms of quoting), and you can't have redirections, pipes...

There's a DEBUG trap that can be called before every command is run

eg

trap 'echo -e "\nStarted at: $(date)\n"' DEBUG

So if I do that:

$ trap 'echo -e "\nStarted at: $(date)\n"' DEBUG
$ pwd

Started at: Thu Aug 18 11:59:33 EDT 2016

/home/sweh
$ echo hello

Started at: Thu Aug 18 11:59:35 EDT 2016

hello
$ sleep 100

Started at: Thu Aug 18 11:59:37 EDT 2016

It's not rewriting the prompt, but you can see how it can be made to output stuff before every comamnd. You can make the trap function as complicated as you need.