lib.py 文件源码

def which(program):
    """Locate `program` in PATH

    Arguments:
        program (str): Name of program, e.g. "python"

    """

    def is_exe(fpath):
        if os.path.isfile(fpath) and os.access(fpath, os.X_OK):
            return True
        return False

    for path in os.environ["PATH"].split(os.pathsep):
        for ext in os.getenv("PATHEXT", "").split(os.pathsep):
            fname = program + ext.lower()
            abspath = os.path.join(path.strip('"'), fname)

            if is_exe(abspath):
                return abspath

    return None