Best way to deal with passing arguments to nested script calls and creating a effective menu driven cli - linux

Question

I am writing a central script, which acts as a menu driven cli through which I trigger other scripts based on the input.
#!/bin/bash
echo "Server Name - `hostname`"
echo "-------------------------------"
echo " M A I N - M E N U"
echo "-------------------------------"
echo "1. init"
echo "2. insert"
echo "3. show"
echo "4. update"
echo "5. rm"
echo "6. ls"
echo "7. shutdown -> shutdown the server"
while :
do
printf '> '
read -r varname
set -- $varname
case $1 in
init)
./init.sh $2
echo $status
;;
insert)
./insert.sh $2 $3 '' $4
;;
show)
./show.sh $2 $3
;;
update)
./insert.sh $2 $3 'f' $4
;;
rm)
./rm.sh $2 $3
;;
ls)
./ls.sh $2 $3
;;
shutdown)
exit 0
;;
exit)
exit 0
;;
*)
#echo "Error: Bad request"
;;
esac
done
Current:
I have purposefully added the print '> ' statement so as to get an interactive interface just like node cli.
insert user1 google 'login:blahblah#gmail.com\npass:blah'
$1 is insert
$2 is user1
$3 is google
$4 is 'login:blahblah#gmail.com\npass:blah'
Expected:
I wish to read arguments the same way we pass arguments when we run a script.
Ex:
sh add.sh 10 20
or
sh add.sh "10" "20"
Either way when we read $1 or $2 in the add shell script, we will be getting 10 and 20 as their values.
insert user1 google 'login:blahblah#gmail.com\npass:blah'
$1 is insert
$2 is user1
$3 is google
$4 is login:blahblah#gmail.com\npass:blah
I do not want to get the input and then remove the trailing quotes. I would like to have the exact behaviour when we run a script and pass arguments.
PS: Please suggest how to get a cli just like node too which has access to previously run commands using the Up arrow.
Thanks in advance

Answer 1

The central idea here seems to revolve around these lines:
read -r varname
set -- $varname
The read command reads a whole line of input as literal text (without the possibility of line continuation) and records it as the value of variable varname, then that variable is expanded to provide arguments to the set builtin. But this is not equivalent to presenting the same command line as shell input.
Of particular relevance to the question is that quotation marks arising from variable expansion are not subject to quote removal. Also, brace and tilde expansion happen prior to variable expansion, so they will not be effective for you either.
What you really seem to want is a double expansion. Specifically, this:
eval "set -- $varname"
Do note that eval is very dangerous and subject to exploitation. For example, consider what would happen a user enters this command into your script (which is supposed running with sufficient privilege to perform a system shutdown):
show pwned; rm -rf /*