# Arguments
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In AWS ParallelCluster 2.x the `$1` arguments was a reserved one, to store the URL of the custom script. If you want to re-use the custom bootstrap scripts created for AWS ParallelCluster 2.x with AWS ParallelCluster 3.x you need to adapt them by considering the shift of the arguments. Please refer to [Moving from AWS ParallelCluster 2.x to 3.x](moving-from-v2-to-v3.md).