That is peculiar, because it seems to be an error raised by the shell, but GitHub Actions expressions are evaluated before the shell code is run...

@Simran-B I also get the bad substitution error with the previous answer, and with this comment I get You have an error in your yaml syntax. Any other ideas?

@1oglop1 @divyegala What do you actually want to achieve? To literally print ${{VAR}} in Bash? What's the purpose, though?

The original question was how to prevent GitHub Actions from interpreting ${{ ... }} as an expression, which can be achieved by using an expression that returns any string. If this is in a run block, the shell interprets whatever that string is, and ${{VAR}} doesn't appear to be valid in Bash (I suppose the original question did not use Bash as the shell).

To print ${{VAR}} with Bash as the shell, this does the trick: ${{ 'echo ''${{VAR}}''' }}
Note that Bash requires single quote marks to not interpret $ but treat it as literal text. Because the GitHub Actions expression uses single quote marks itself, you need to escape the ' inside of the string by doubling it (''). What Bash receives is echo '${{VAR}}' in this case, which literally prints ${{VAR}}.

Thank you for the explanation @Simran-B. I actually wanted a variable expansion to occur in a bash script. I was able to use ${{ '${VAR}' }} and that did the trick for me, by ensuring VAR was initialized in bash before the command that utilized it was run.