I'd skip making a shell command to get multiple modules and use a drush make file instead.
What is a makefile?
A makefile is a macro for installing Drupal. It contains a list of
files that can be fetched using the power of drush, the command line
tool for administering Drupal.
Using this generator you can specify different Drupal core
distributions, modules, themes, and external libraries like jQuery or
The end result is a small text file containing the DNA for a specific
Drupal setup — YOUR perfect setup!
(taken from the What section of drushmake.me)
You can use the service as drushmake.me to generate the make file without having to type it all out yourself if it's relatively simple :)
As an example of what a make file can look like, check here. It's old, and I've not updated it in ages but you'll get the idea.
There's also a pretty concise overview of make files here.