This scenario is configured with three consoles.
Consoles, scripts and most other scenario properties are set in file .katapod-config.json.
Katapod can execute commands (on a target console) in two ways:
- when certain pages are loaded and rendered;
- when the user clicks on command code blocks.
The welcome messages on the first two consoles are the result of scripts being executed
upon loading of intro.md. This is the (fixed) name of the entry-point page.
Clicking on an executable code block launches the command in a console. This clears the second console:
### termTwo
clear
Do the same with the first console:
clear
Commands can bear a specification of how many times they are allowed to be run.
For example, the message on the first console for the intro-page has "maxInvocations": 2.
The intro-page-load for the second console triggers two commands,
the first implicitly with the default of executing only once,
the second with "maxInvocations": "unlimited".
✅ Try going to the intro to check what gets executed again. Then come back here.
✅ Now clear the consoles and go once more to the intro. What command ran only once? Twice? Forever?
Note: keep the source code for the scenario at hand to make sense of what you do!
Code blocks on the page are executed with a click on them.
### term_3
echo "Third terminal."
"Naked" code blocks implicitly run on the first terminal
date
You specify the target terminal by putting a line in the code block which starts with ### (note the space after the pounds),
followed by the terminal ID:
### termTwo
echo "Second terminal."
Moot ### lines do no harm:
###
date
When there are multiple ### lines, the last wins:
### term_3
echo "Nyvpr fraqf frperg zrffntr gb Obo." | tr 'a-zA-Z' 'n-za-mN-ZA-M'
### cqlsh
The ### termTwo syntax is actually shorthand for ### {"terminalId": "termTwo"}. So this:
### termTwo
whoami
is equivalent to this:
### {"terminalId": "termTwo"}
whoami
Run this command on the first terminal:
### {"terminalId": "cqlsh", "maxInvocations": 2}
ls scenario_scripts
Try runnig it a second time. All good? I bet you cannot run it a third time, though. Try it. (You may have guessed by now that the default number of invocations for in-page code blocks is "unlimited").
Start Python on the third terminal:
### term_3
python
This command launches a loop that will go on forever (note a newline at the end for the Python REPL to start looping):
### term_3
import time
i = 0
while True:
print('Looping ... %i' % i)
i += 1
time.sleep(0.5)
Good news: you can inject a Ctrl-C right before executing another command.
The following block, indeed, will send a Ctrl-C to the loop to stop it,
then will exit the Python REPL and run a shell command:
### {"terminalId": "term_3", "macrosBefore": ["ctrl_c"]}
# (a Ctrl-C to stop the running loop, then:)
exit()
# we're back to the shell:
date +"%Y-%m-%d"