I seem to get into a paradoxical situation. I have a long string stored in a variable `$abstract` like this:

```
abstract='test1 and "test2"'

```

you see that there is a quotation mark in the string, and I want to send this string to a command as a single argument, I tried the following command:

```
command_name "$abstract"

```

after the variable substitution, it became: `command_name test1 and "test2"`. And if i try:

```
command_name \"$abstract\"

```

it becomes: `command_name "test1 and "test2""`. Both are not what I wants. Can anyone tell me how to achieve my goal?