I want to extract a specific string to a specific character in a shell script.

The following log files are available:

aaa1234.234;
bbbb5678.345;
ccc12345.356;

aaa2345.344;
bbbb6789.354;
ccc23456.678;

I want to extract only the number of bbbb from "bbb" to ";" from this file.
There is no string like bbb.
The number of digits in this number is indefinite, and it is also uncertain how many sets of data such as a-c, but
If possible, could you store it in different variables or in one variable, including line breaks?

This is a supplement

ans=`grep-o`bbbb[^;]*`test.txt`

was able to get out of bbbb;
In addition, sed replaces bbbb,

ans=`echo "$ans" | sed-e's /^bbb//'`

was able to extract lines with new lines.
I'd like to put this in a different variable for each line.
If I don't know the number of lines, it will be difficult to separate them.

Supplement 2
It worked by specifying a new line in IFS.
Thank you.