Technology Tales

Clearing the Julia REPL

23^rd September 2024

During development, there are times when you need to clear the Julia REPL. It can become so laden with content that it becomes hard to perform debugging of your code. One way to accomplish this is issuing the CTRL + L keyboard shortcut while focus is within the REPL; you need to click on it first. Another is to issue the following in the REPL itself:

print("\033c")

Here \033 is an escape code in octal format. It is often used in terminal control sequences. The c character is what resets the terminal to its initial state. Printing this sequence is what does the clearance, and variations can be used to clear other kinds of console screens too. That makes it a more generic solution.

Dropping to an underlying shell using the ; character is another possibility. Then, you can use the clear or cls commands as needed; the latter is for Windows systems.

One last option is to define a Julia function for doing this:

function clear_console()
    run(`clear`)  # or `cls` for Windows
end

Calling the clear_console function then clears the screen programmatically, allowing for greater automation. The run function is the one that sends that command in backticks to the underlying shell for execution. Even using that alone should work too.

Killing a hanging SSH session

20^th April 2018

My web hosting provider offers SSH access that I often use for such things as updating Matomo and Drupal, together with more intensive file moving than an FTP session can support. However, I have found recently that I no longer can exit cleanly from such sessions using the exit command.

Because this produces a locked terminal session, I was keen to find an alternative to shutting down the terminal application before starting it again. Handily, there is a keyboard shortcut that does just what I need.

It varies a little according to the keyboard that you have. Essentially, it combines the carriage return key with ones for the tilde (~) and period (.) characters. The tilde may need to be produced by the combining the shift and backtick keys on some keyboard layouts, but that is not needed on mine. So far, I have found that the <CR>+~+. combination does what I need until SSH sessions start exiting as expected.