FAQ

General and Miscellaneous Questions

This is a place for questions that do not fit on any of our topical FAQ/Help pages, which you can find on the FAQ/Help portal.

Remember: if you don't find what you need, or if you'd like to ask a question, then please email help@sagemath.com at any time. We'd love to hear from you! Please include a link (the URL address in your browser) to any relevant project or document, as part of your email.

List of Questions:

• What tools are available for course management?
• How can I use Python3 by default in Sage worksheets?
• I created an ssh key in my project; how do I easily copy it?
• How can I download a whole directory?
• How is CoCalc backed up?
• Can I pay with Paypal?
• If I have a license for proprietary software, can I run it in a CoCalc project?
• How can I clear the scrollback buffer in a terminal without deleting the terminal?
• What if my question isn't answered above?

Question: What tools are available for course management?

See the tutorial for anyone wanting to use CoCalc for teaching.

Question: How can I use Python3 by default in Sage worksheets?

First, try putting this in a cell of a Sage worksheet:

%auto
%default_mode python3

Then the rest of that worksheet will use Python3.

If you make a sage worksheet called

templates/linux/default.sagews

with the above content, it'll be used by default whenever you open a new worksheet in that project. You can create the above file quickly by navigating to your home directory in the file browser, then pasting the above in filename search in the upper left.

Question: I created an ssh key in my project; how do I easily copy it?

If you type ssh-keygen in a terminal, then you'll generate an ssh key, which you might use with github (say) or sage's trac to easily push and pull to repositories. To copy this ssh key, you could type cat .ssh/id_rsa.pub and copy in the terminal, but you'll have to manually delete a bunch of newlines. Alternatively, do the following:

1. In the project file list, click on the icon that looks like an eye in the middle on the right side of the screen to reveal hidden files (those that start with a dot).

2. Click on the .ssh directory -- you can easily find it by typing "ssh" in the search box labeled "choose files..." on the left.

3. Click on id_rsa.pub, then highlight everything and copy as usual.

4. Click the eye again to turn off viewing hidden files.

Alternatively, type this into the small "terminal command" box in "files": cat ~/.ssh/*.pub. Below the box, you can conveniently copy/paste it!

You can also type the following into a full terminal: open ~/.ssh/id_rsa.pub

Question: How can I download a whole directory?

There is currently no provision to download an entire directory. To accomplish this, you can easily create a .zip-archive. Above the files view, on the right, there is a command-box. For a directory called "My Homework", type in:

zip download-homework.zip "My Homework"

The directory name needs to be exactly the same, including upper and lowercase letters, and any space characters need to be protected by quoting the entire name.

If successful, a new file download-homework.zip should appear.

Question: How is CoCalc backed up?

Here's the current (as of May 2015) backup system:

1. The files in your project sit on a VM at google, whose filesystem is snapshotted twice per day, with snapshots saved for about 10 days.

2. The files are rsync'd to another server whenever your project is saved (so every 5 minutes when actively used).

3. The files and the second server are snapshotted using ZFS with snapshots saved for several months (but trimmed over time).

4. Every few hours a bup (=git) archive is made of modified projects and saved in a Google cloud storage nearline bucket.

5. At least once per week (and usually once per day), I rsync the new bup archives to an encrypted USB drive, which is usually not connected to the internet (and with me personally in most cases).

6. I periodically rsync that usb drive to another encrypted USB drive.

7. I periodically swap that usb drive from above out with another encrypted USB drive that is kept in a locked office elsewhere.

Question: Can I pay with Paypal?

YES The only restriction is that because it is a manual process, at this time, we can accept only paypal for course subscriptions and 1-year subscriptions.

E-mail wstein@sagemath.com to set this up.

If I have a license for proprietary software, can I run it in a CoCalc project?

CoCalc runs on virtual computers in Google Compute Engine (Google’s cloud), on Ubuntu Linux. If you have a valid license to run software, it may be possible to install and run it on CoCalc.

How can I clear the scrollback buffer in a terminal without deleting the terminal?

In a "plain" terminal, type in "reset". That's command tells the terminal to reinitialize itself. This should clear the buffer, too.

If you use tmux or another multiplexer, it sits on top of that terminal interface. There, you run "reset" and then close and reopen the terminal tab.

In both cases, the terminal file, the session and chat is still there and you didn't lose any history.

What if my question isn't answered above?

Email help@sagemath.com with lots of details about your question. Do not hesitate to immediately email us, because we are eager to hear from you!