> For the complete documentation index, see [llms.txt](https://docs.instruqt.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.instruqt.com/sandboxes/lifecycle-scripts/lifecycle-scripts-examples.md).

# Example scripts

{% hint style="warning" %}
These example scripts may use software that is not be available on every operating system.
{% endhint %}

## Track setup scripts

### Wait for bootstrap

Wait for the Instruqt bootstrap process to complete.

{% tabs %}
{% tab title="Bash" %}

```bash
#!/bin/bash
set -euxo pipefail

until [ -f /opt/instruqt/bootstrap/host-bootstrap-completed ]; do
    echo "Waiting for instruqt bootstrap to complete"    sleep 1
done
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
The bootstrap process may overwrite user files like `.bashrc`. Wait is encouraged!
{% endhint %}

### Wait for service

Wait for a specific web service in your setup script to finish booting.

{% tabs %}
{% tab title="Bash" %}

```bash
while ! curl --fail --output /dev/null https://<hostname>:<port>/<path> 
do
    sleep 1
done
```

{% endtab %}
{% endtabs %}

### Create a file

Create a file using heredoc method.

{% tabs %}
{% tab title="Bash" %}

```bash
cat > /file/to/create <<EOF
# Some configuration file
setting_one = true
another_setting = false
EOF
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
You can append to a file by using `>>` as opposed to `>`.
{% endhint %}

### Download files

Download files to the local system.

{% tabs %}
{% tab title="Bash (Git)" %}

```bash
git clone https://githost.com/repo <local_dir>
```

{% endtab %}

{% tab title="Bash (Curl)" %}

```bash
curl http://example.com/folder/big-file.iso -O <local_file>
```

{% endtab %}
{% endtabs %}

### Start background process

Start a process in the background so your script does not hang.

{% tabs %}
{% tab title="Bash" %}

```bash
nohup ./myprogram > foo.out 2> foo.err < /dev/null & disown
```

{% endtab %}
{% endtabs %}

## Challenge check scripts

### File exists

Check if a file exists:

{% tabs %}
{% tab title="Bash" %}

```bash
#!/bin/bash
set -euxo pipefail

if [ -f /home/user/file.txt ]; then
    echo "The file at /home/user/file.txt exists"
fi
```

{% endtab %}
{% endtabs %}

### File doesn't exist

Check if a file **doesn't** exist (or is not a file):

{% tabs %}
{% tab title="Bash" %}

```bash
#!/bin/bash
set -euxo pipefail

if [ ! -f /home/user/file.txt ]; then
    fail-message "No file was found at /home/user/file.txt"
fi
```

{% endtab %}
{% endtabs %}

### Directory exists

Check if a directory exists:

{% tabs %}
{% tab title="Bash" %}

```bash
#!/bin/bash
set -euxo pipefail

if [ -d /root/folder ]; then
    echo "The directory at /root/folder exists"
fi
```

{% endtab %}
{% endtabs %}

### Directory doesn't exist

Use the following code in your life cycle script to check if a folder **doesn't** exist (or is not a directory)

{% tabs %}
{% tab title="Bash" %}

```bash
#!/bin/bash
set -euxo pipefail

if [ ! -d /root/folder ]; then
    fail-message "The folder at /root/folder doesn't exists"
fi
```

{% endtab %}
{% endtabs %}

### File contains certain text

Check if a file contains certain text.

{% tabs %}
{% tab title="Bash" %}

```bash
#!/bin/bash
set -euxo pipefail

if ! grep "text to find" /path/to/file; then
    fail-message "The file doesn't contain the required text"
fi
```

{% endtab %}
{% endtabs %}

### Specific command is installed

Check that a specific command is executable with the -x flag.

{% tabs %}
{% tab title="Bash" %}

```bash
#!/bin/bash
set -euxo pipefail

if ! [[ -x /usr/local/bin/command ]]; then
  fail-message "Oops, command was not found or is not executable."
fi
```

{% endtab %}
{% endtabs %}

### Service is running

Check if a service is running.

{% tabs %}
{% tab title="Bash" %}

```bash
#!/bin/bash
if pgrep -x SERVICE >/dev/null; then
    echo "The X service is running"
fi
```

{% endtab %}
{% endtabs %}

{% hint style="info" %}
Replace SERVICE with a service name running on that system.
{% endhint %}