You can use the `diff` command to compare two multi-line Bash variables and list lines that are unique to each variable. Here's an example of how to do this:
```bash
#!/bin/bash
# Create two multi-line variables
variable1="apple
banana
cherry
date
elderberry"
variable2="cherry
date
fig
grape
honeydew"
# Use process substitution to pass variables to diff
diff <(echo "$variable1") <(echo "$variable2") | grep -E '^<|>'
```
In this script:
1. Two multi-line variables, `variable1` and `variable2`, are defined.
2. The `diff` command is used with process substitution (`<(...)`) to compare the contents of the two variables line by line.
3. The `diff` output is piped to `grep` to filter lines that begin with `<` (indicating lines unique to `variable1`) or `>` (indicating lines unique to `variable2`).
Running this script will list the lines that are in one variable but not in the other. In the example above, it will display:
```
< apple
< banana
< elderberry
> fig
> grape
> honeydew
```
This shows lines that are in `variable1` but not in `variable2` and vice versa. You can adjust the script to work with your own multi-line variables.