I'd like to be able to post to and get information from a Linux command line (and therefore be able to write little bash scripts to work with projects) similar to
gcalcli for Google Calendar.
Is this possible with Trello?
Trello does have an API which is documented here. Using that you should be able to write scripts to perform any action it supports.
It doesn't look like anyone has written a bash interface as yet, however you could possibly make a Python based command line tool based on the libraries listed on that page.
Not sure if you mind having to rely on ruby gems, but I was looking for a CLI trello client and found:
Looks like it supports TSV and JSON output, so it should be pretty simple to write basic scripts using the shell and jq or other standard unix utilities. It doesn't seem like it is as polished as gcalcli, but seems like it might be close to what you are looking for.