def run_command(self, cmd: str) -> str:
        """
        Run a command line (with a shell).

        Returns:
            str: the output of the command.

        """
        self.print(f"\n### ========================\n$ {cmd}")
        start = time.perf_counter()
        proc = subprocess.run(
            cmd,
            shell=True,
            check=False,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
            env=cast(Mapping[str, str], self.env_vars),
        )
        output = proc.stdout.decode("utf-8")
        self.last_duration = time.perf_counter() - start
        self.print(output, end="")
        self.print(f"(was: {cmd})")
        self.print(f"(in {os.getcwd()}, duration: {self.last_duration:.3f}s)")

        if proc.returncode != 0:
            self.print(f"ERROR: command returned {proc.returncode}")
            raise Exception(
                f"Command failed ({proc.returncode}): {cmd!r}, output was:\n{output}"
            )

        return output.strip()

        Run a command line (with a shell).

        Returns:
            str: the output of the command.

        
benchmark/benchmark.py