Check that there are at least two arguments given in a bash script

Use the $# special variable. Its value is the number of arguments. So if you have a script that contains only:

echo $#

and execute it like this:

thatscript foo bar baz quux

It’ll print 4.

In your case you may want to do something like:

if [ $# -lt 2 ]; then
    # TODO: print usage
    exit 1
fi