Variable as multiple command parameters ignore quotes in Bash

Question

I want to insert a variable (basically a read text file) into a command body as multiple parameters, but this doesn't work because the variable is not resolved properly.

My variable

MAIN_MENU="1 'Create new image' 2 'Start image as overriding' 3 'Start image as snapshot' 4 'Install OS' 5 'Settings'"

Echoes:

echo $MAIN_MENU
1 'Create_new_image' 2 'Start_image _as_overriding' 3 'Start _image_as_snapshot' 4 'Install_OS' 5 'Settings'

Which is what I expect and if I copy paste the echo result (by hand) to command parameters like below, it works.

dialog --title "Title" --menu 'Choose operation:' 0 0 5 1 'Create new image' 2 'Start image as overriding' 3 'Start image as snapshot' 4 'Install OS' 5 'Settings'

In this case, parameters are ... 1; Create new image; 2; Start image as overriding ...

However, when I insert the parameters as a variable, it ignores the single quotes completely..

MAIN_MENU="1 'Create new image' 2 'Start image as overriding' 3 'Start image as snapshot' 4 'Install OS' 5 'Settings'"
dialog --title "Title" --menu 'Choose operation:' 0 0 5 $MAIN_MENU

Basically leaving single quotes there, but also separating the parameters by spaces..

In this case, parameters are ... 1; 'Create; new; image'; 2; 'Start; image; as; overriding'; ...

No amount of quote swapping resulted in coveted results for me.

Answer 1

After parameter expansion, any quotes in the result are treated as literal characters, not syntax for escaping whitespace. The correct way to create a list of values is to use an array, which acts as a second layer of quoting to allow whitespace in each element. As a bonus, array assignments also allow for more readable formatting.

MAIN_MENU=(
  1 'Create new image'   # Comments can be added, as well
  2 'Start image as overriding'
  3 'Start image as snapshot'
  4 'Install OS'
  5 'Settings'
)
dialog --title "Title" --menu 'Choose operation:' 0 0 5 "${MAIN_MENU[@]}"