So I run radare2 from the command line with r2 - and attempt to display the help with the ? command. I read this line which says:

?[??][expr] Help or evaluate math expression

I am not sure how to read this. I assume the first ? is Help command. And the rest [??][expr] is evaluate math expression. However, something like this ?? 0xa does not return anything. So, my question is how to correctly interpret this output from the help.

  • 1
    ? is indeed Help. To evaluate expression you need ??? expr.
    – bart1e
    Commented Mar 4, 2021 at 10:54
  • Have you tried > ? 0x32
    – pancake
    Commented Mar 4, 2021 at 11:07

1 Answer 1


It took me some time to realize that the 2 helps were kind of combined into one.

The first question mark symbol can mean either help or evaluate math expression. The second and third are optional if used in the context of evaluating an expression.

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