Why not working shell command with variables on envoy?

Question

I have simple Envoy setup. A server:

@task('build_todo_list', ['on'=> $server])
    echo 'Build todo list'
    cd {{ $releases_dir }}
    current=$(ls -td -- * | head -n 1 | cut -d'/' -f1)

    d=$(echo $current | cut -c 1-8)
    echo $d
    since=$(date -d $d +"%Y-%m-%d")
    until=$(date +"%Y-%m-%d")
    echo $since
    echo $until
    cd {{$source_dir}}
    git log staging --pretty="%an %B" --since=$since --until=$until | grep 'Fixed \| Did'
@endtask

But i have an error because i use $since and $until variables in my git log command. And this variables good work with echo command.

Answer 1

Problem has been not variables. If between "since" and "until" not have records - will not be task complete successfully.