SHELL_NAMES = ( {"sh", "bash", "dash", "ash"} # Bourne. | {"csh", "tcsh"} # C. | {"ksh", "zsh", "fish"} # Common alternatives. | {"cmd", "powershell", "pwsh"} # Microsoft. | {"elvish", "xonsh", "nu"} # More exotic. ) class ShellDetectionFailure(EnvironmentError): pass