Actions: Variable substitution in commented lines

If there are any variables in the commented lines get substituted in the logs of action workflow.

To Reproduce Steps to reproduce the behavior:

1. Write Any simple action work flow
2. In a job write following step

 - name: Build App
    run: |
          #cd ${{ github.workspace }}

1. Navigate to the logs of the step and expand the command. You can see the following

#cd /home/user/actions-runner/_work/cd-demo-app/cd-demo-app

Screenshot:

Expected behavior As the line was commented, it is expected not to substitute the variable. But the variable is getting substituted in the logs as shown in the snapshot

Runner Version and Platform

Runner version - 2.279.0 Running on Linux - x64

[TingluoHuang]

The runner doesn’t know it’s a comment for a given shell. The runner treat all inputs as string.

[TingluoHuang]

@girishenoy2003 ${{ github.workspace }} is not a variable, it’s an expression syntax for GitHub Actions, it will get evaluated and expanded before executing any script. https://docs.github.com/en/actions/learn-github-actions/expressions#about-expressions