Helper scripts
This page describes helper scripts that let you take a shortcut.
When bootstrapping a sandbox container or virtual machine, Instruqt injects a couple of helper scripts. These scripts assist you in setting up the environment or applying check scripts. See the currently available set of helper scripts on GitHub.
Helper scripts assume the container or virtual machine has a POSIX shell available at /bin/sh.
fail-message and set-workdir are the most common helper scripts and are highlighted here.

fail-message

Synopsis

fail-message["message"]

Description

The fail-message script can be used to provide feedback to the learner when writing check scripts. The function will write a given string to stdout, prefixed with FAIL:.

Argument

message
The fail message you want to show to the learner.

Example

See the topic Lifecycle scripts for details on writing check scripts like the following example:
Bash
#!/bin/bash
# check
echo "Checking the solution of the challenge"
if [ !$EVERYTHING_WENT_WELL ]; then
fail-message "Your challenge failed because of REASON"
# which is equivalent to
echo "FAIL: Your challenge failed because of REASON"
exit 1
fi

set-workdir

Synopsis

set-workdir[directory]

Description

The set-workdir script can be used to change the active working directory for a terminal tab from a challenge setup script.

Argument

directory
The directory you want to set as the active working directory.

Example

To set the usr directory as the active working directory:
Bash
#!/bin/bash
# setup
set-workdir usr
The set-workdir script is implemented using $HOME/.bashrc. This means you will have to use bash as the shell for the container or virtual machine.
If you don't have bash available, you can achieve the same behavior by adding a cd /path/to/workdir command to the shell's profile (e.g. $HOME/.profile or /etc/profile).
When using the ash shell (which most busybox based containers do), you can also indicate that the .bashrc profile needs to be loaded. To do so, add an environment variable ENV with value $HOME/.bashrc. to the container's environment variables in the config.yml.
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