Output the theoretical `.command.sh` file when using stub

[awgymer]

It would be great if there was a way to run a workflow with -stub but also get the result of what would have run in the script section.

Currently I have a work around that looks something like this:

script:
def prefix = task.ext.prefix ?: "${meta.id}"
def args = teask.ext.args ?: ""
"""
some command \
    $input \
    $args 
"""

stub:
def prefix = task.ext.prefix ?: "${meta.id}"
def args = teask.ext.args ?: ""
command = """
some command \
    $input \
    $args 
"""

"""
echo '${command}'

touch myoutput.txt
"""

But obviously this creates a lot of code duplication and requires one to carefully keep the stub section aligned with every chaneg to the script section.

Suggest implementation

Could be default to output the would-be script to .command.sh.stub or something. Or it could be an additional option like --stub-run-verbose or some such. I am not sure how easy this would be to implement with how nextflow is written in honesty.