BASH - how echo works inside EOF tags - bash

Question

I would like to execute the followings:
PASSWORD="mypassword"
RUNCOMMAND=$(cat <<EOF
echo $PASSWORD | sudo -S sudo echo "this is it babe"
EOF
)
But instead of this is it babe, I get the following result:
mypassword | sudo -S sudo echo "this is it babe"
I tried with cat <<\EOF, cat <<'EOF' still no luck.
Any ideas?

Answer 1

You are confusing a heredoc with a pipeline.
heredoc with variable expansion:
cat <<EOF
some text, possibly with variables: ${HOME} / $(whoami)
EOF
some text, possibly with variables: /home/attie / attie
heredoc without variable expansion:
cat <<"EOF"
some text, possibly with variables: ${HOME} / $(whoami)
EOF
some text, possibly with variables: ${HOME} / $(whoami)
pipeline with variable expansion (note the quotes, "):
echo "some text, possibly with variables: ${HOME} / $(whoami)" | cat
some text, possibly with variables: /home/attie / attie
pipeline without variable expansion (note the quotes, '):
echo 'some text, possibly with variables: ${HOME} / $(whoami)' | cat
some text, possibly with variables: ${HOME} / $(whoami)
${...} expands an environment variable
$(...) runs a command, and substitutes its stdout
It also looks like you're trying to have your password entered into sudo - this won't work, as sudo will repoen the terminal to acquire your password, before passing it's stdin to the final application.

Answer 2

You are starting from a false premise, that eval $RUNCOMMAND is something you should do. It is not; variables are for data, functions are for code.
run_command () {
docker_run_options=(
--restart=always
--name "${USER_NAME}_$(date +%Y%m%d-%H%M%S)"
-d
-e "VIRTUAL_HOST=$USER_VIRTUAL_HOST"
-e "VIRTUAL_PORT=$USER_VIRTUAL_PORT"
-e "PORT=$USER_VIRTUAL_PORT"
-p "$USER_VIRTUAL_PORT:$USER_VIRTUAL_PORT"
)
echo "$1" | sudo -S sudo docker run "${docker_run_options[#]}" "$USER_IMAGE"
}
fun_run_command () {
run_command "PASSWORD"
}

Answer 3

The final solution is rather simple:
PASSWORD="mypassword"
RUNCOMMAND=$(cat <<EOF
echo $PASSWORD | sudo -S sudo echo "this is it babe"
EOF
)
And execute it via eval:
eval $RUNCOMMAND
Sorry for stealing your times with this obvious problem guys:)
The usecase for the above is to echo a given command before really executing it.
Like this:
fun_run_command(){
# execute the final command
echo `eval $RUNCOMMAND`
}
fun_echo_command(){
# echo the command which will be launched (fun_run_command())
echo ${RUNCOMMAND//$PASSWORD/PASSWORD}
}
RUNCOMMAND=$(cat <<EOF
echo $PASSWORD | sudo -S sudo docker run --restart=always \
--name ${USER_NAME}_`date +%Y%m%d-%H%M%S` \
-d \
-e "VIRTUAL_HOST=$USER_VIRTUAL_HOST" \
-e "VIRTUAL_PORT=$USER_VIRTUAL_PORT" \
-e "PORT=$USER_VIRTUAL_PORT" \
-p $USER_VIRTUAL_PORT:$USER_VIRTUAL_PORT \
$USER_IMAGE
EOF
)
As you can see the command what I launch is quite long,
so it is always make sense to doublecheck what is executed by the script.
Having copy&paste the same command to multiple function is prone to error.