Ansible Roles：从目录结构到参数校验与依赖复用-未完纪

原文：Roles；作者：Ansible 项目贡献者与社区文档团队（页面无个人署名）。中文全文译写与编者审核：未完纪。核对日期：2026-10-05。

依据 2026-10-05 抓取的 Ansible Community Documentation latest 页面整理。角色参数校验始于 2.11；roles 下 vars 的作用域在 ansible-core 2.15 前后不同。latest 是滚动文档，部署前应按实际 ansible-core 版本核对。

图 1：角色从文件结构进入 play 的逻辑流程。参数校验和依赖的实际先后关系以正文说明为准。

Role（角色）按照约定的文件结构，自动载入相互关联的变量、文件、任务、处理器和其他 Ansible 内容。把一组运维操作组织成角色后，就可以在不同 playbook 中重复使用，也便于向其他使用者分发。角色既是一种内容组织方式，也是一套明确的载入规则；理解这些规则，比简单地把任务移进 roles 目录更重要。

一、角色目录结构

角色有七个主要的标准目录，每个角色至少包含其中一个；没有用到的目录可以省略。下例先列出 playbook，再列出同级 roles 目录中的多个角色。library、module_utils 和各类插件目录是额外扩展，并不属于必须齐备的七个目录。

playbook 文件

# playbooks
site.yml
webservers.yml
fooservers.yml

roles/
    common/               # this hierarchy represents a "role"
        tasks/            #
            main.yml      #  <-- tasks file can include smaller files if warranted
        handlers/         #
            main.yml      #  <-- handlers file
        templates/        #  <-- files for use with the template resource
            ntp.conf.j2   #  <------- templates end in .j2
        files/            #
            bar.txt       #  <-- files for use with the copy resource
            foo.sh        #  <-- script files for use with the script resource
        vars/             #
            main.yml      #  <-- variables associated with this role
        defaults/         #
            main.yml      #  <-- default lower priority variables for this role
        meta/             #
            main.yml      #  <-- role dependencies
        library/          # roles can also include custom modules
        module_utils/     # roles can also include custom module_utils
        lookup_plugins/   # or other types of plugins, like lookup in this case

    webtier/              # same kind of structure as "common" was above, done for the webtier role
    monitoring/           # ""
    fooapp/               # ""

在多数目录中，Ansible 默认查找 main.yml，也接受 main.yaml 或不带扩展名的 main。各目录的意义如下。

路径	作用与边界
tasks/main.yml	提供角色执行的任务列表。
handlers/main.yml	导入父 play 的处理器，可被本角色、其他角色及 play 中的任务使用。
defaults/main.yml	提供很低优先级的默认变量。本角色自身默认值优先于其他角色默认值，但其他变量来源均可覆盖它。
vars/main.yml	向 play 提供高优先级变量，使用时要注意变量优先级与覆盖关系。
files/stuff.txt	供角色及其子内容引用的普通文件。
templates/something.j2	供角色及其子内容使用的模板。
meta/main.yml	依赖和 Galaxy 元数据，例如支持的平台。独立角色上传 Galaxy 需要此文件，play 中使用角色不强制要求。

上述具体文件本身都不是角色成立的必备条件。只提供 files/something.txt，或者只提供 vars/for_import.yml，仍然可以是有效角色。“独立角色”指可以单独安装、并非某个 collection 组成部分的角色；它还能携带 library/my_module.py 等自定义模块或插件。vars 与 defaults 中的变量公开到 play 作用域的行为，应结合 import_role/include_role 的 public 选项控制；不能把文件放进角色目录就视为私有数据。

部分目录可以增加其他 YAML 文件，但这些文件不会默认自动执行。可以显式 include/import，也可以在 include_role/import_role 中指定入口。常见做法是把平台相关任务拆开，由 tasks/main.yml 按操作系统选择：

按 Red Hat 与 Debian 系列系统导入安装任务

# roles/example/tasks/main.yml
- name: Install the correct web server for RHEL
  ansible.builtin.import_tasks: redhat.yml
  when: ansible_facts['os_family']|lower == 'redhat'

- name: Install the correct web server for Debian
  ansible.builtin.import_tasks: debian.yml
  when: ansible_facts['os_family']|lower == 'debian'

# roles/example/tasks/redhat.yml
- name: Install web server
  ansible.builtin.yum:
    name: "httpd"
    state: present

# roles/example/tasks/debian.yml
- name: Install web server
  ansible.builtin.apt:
    name: "apache2"
    state: present

也可以在载入角色时直接指定某个任务文件，从而绕过 tasks/main.yml：

通过 tasks_from 选择 apt.yml

- name: include apt tasks
  ansible.builtin.include_role:
      name: package_manager_bootstrap
      tasks_from: apt.yml
  when: ansible_facts['os_family'] == 'Debian'

defaults 和 vars 还允许嵌套目录。若作为变量入口的 main 是目录，Ansible 会按字母顺序读取其中的变量文件和子目录；同一层同时存在子目录与文件时，先处理目录。下面的 vars/main 展示这种布局。

变量入口也可以是含多个文件的目录

roles/
    common/          # this hierarchy represents a "role"
        vars/
            main/    #  <-- variables associated with this role
                first_nested_directory/
                    first_variables_file.yml
                second_nested_directory/
                    second_variables_file.yml
                third_variables_file.yml

二、存储角色与查找路径

默认情况下，Ansible 会在这些位置寻找角色：使用中的 collections、相对于 playbook 文件的 roles/ 目录、配置的 roles_path，以及 playbook 所在目录。roles_path 的默认值是 ~/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles。

如果角色放在其他位置，应配置 roles_path。把共享角色放在一个统一位置，便于多个 playbook 使用；相关配置由 ansible.cfg 等 Ansible 配置机制管理。也可以直接给出角色的完整路径：

用绝对路径引用角色

---
- hosts: webservers
  roles:
    - role: '/path/to/my/roles/common'

三、在 playbook 中使用角色

角色有四种常见入口：在 play 层使用 roles；在 tasks 中用 include_role 动态载入；在 tasks 中用 import_role 静态导入；或作为另一个角色 meta/main.yml 中的依赖。选择入口时，需要同时考虑执行顺序、标签传播与变量范围。

在 play 层使用 roles

经典角色调用方式

---
- hosts: webservers
  roles:
    - common
    - webservers

对于 roles 下的每个角色 x，Ansible 会查找 roles/x/tasks、handlers、vars、defaults、meta 的 main 入口。角色里的 copy、script、template 和 include 任务，可以直接引用对应 files、templates、tasks 目录中的文件，无须自行拼接绝对或相对路径。vars 和 defaults 的 main 也可以是目录。include_role/import_role 能选用不同的入口文件名，但 meta 目录不能这样自定义。

play 层 roles 被视为静态导入，并在解析 playbook 时处理。一个 play 的执行顺序是：

执行 pre_tasks。
执行 pre_tasks 通知的 handlers。
按 roles 列表顺序执行角色；每个角色的 meta/main.yml 依赖先执行，并受条件和标签过滤影响。
执行 play 中的 tasks。
执行 roles 或 tasks 通知的 handlers。
执行 post_tasks。
执行 post_tasks 通知的 handlers。

如果依赖 pre_tasks、post_tasks 或角色依赖来控制维护窗口、监控停报或负载均衡摘流，就要给这些步骤添加相应标签，并在筛选执行时一并选择。只给主体任务加标签，可能破坏原本的前后操作顺序。roles 条目还可以接受变量和标签：

给同一应用角色传递不同配置及标签

---
- hosts: webservers
  roles:
    - common
    - role: foo_app_instance
      vars:
        dir: '/opt/a'
        app_port: 5000
      tags: typeA
    - role: foo_app_instance
      vars:
        dir: '/opt/b'
        app_port: 5001
      tags: typeB

在 role 条目上添加的标签会应用到该角色的全部任务。需要注意版本差异：ansible-core 2.15 之前，roles 部分的 vars 会加入 play 变量，因此角色执行之前和之后的任务都可能看到它们；可通过 DEFAULT_PRIVATE_ROLE_VARS 改变旧行为。较新版本中，这里的 vars 不再泄漏到 play 变量作用域。这个版本说明与角色文件 defaults/vars 的 public 设置是不同问题。

include_role：动态复用

include_role 可以出现在 tasks 的任意位置，角色在运行到该任务时载入。与总是在普通 tasks 前执行的 play 级 roles 不同，动态角色前面的普通任务会先执行，后面的任务会后执行。

在普通任务之间动态载入角色

---
- hosts: webservers
  tasks:
    - name: Print a message
      ansible.builtin.debug:
        msg: "this task runs before the example role"

    - name: Include the example role
      ansible.builtin.include_role:
        name: example

    - name: Print a message
      ansible.builtin.debug:
        msg: "this task runs after the example role"

动态载入时也可以传入变量、标签等关键字：

动态角色上的 vars 与 tags

---
- hosts: webservers
  tasks:
    - name: Include the foo_app_instance role
      ansible.builtin.include_role:
        name: foo_app_instance
      vars:
        dir: '/opt/a'
        app_port: 5000
      tags: typeA
  # ...

include_role 任务上的标签只标记 include 语句本身，不会自动传播给角色所有任务。因此，使用 --tags 筛选时，角色内部需要执行的任务也应带有对应标签。以下示例则通过 when 只在 Red Hat 系列主机载入角色：

附带条件的动态载入

---
- hosts: webservers
  tasks:
    - name: Include the some_role role
      ansible.builtin.include_role:
        name: some_role
      when: "ansible_facts['os_family'] == 'RedHat'"

import_role：静态复用

import_role 也可以放在 tasks 的任意位置，但采用静态导入，其行为与 roles 关键字类似。导入语句所在的位置决定任务序列中的相对位置：

在任务列表中静态导入角色

---
- hosts: webservers
  tasks:
    - name: Print a message
      ansible.builtin.debug:
        msg: "before we run our role"

    - name: Import the example role
      ansible.builtin.import_role:
        name: example

    - name: Print a message
      ansible.builtin.debug:
        msg: "after we ran our role"

导入时可以附带变量和其他关键字。若在 import_role 语句上设置标签，标签会应用到角色中的全部任务，这与 include_role 的标签规则不同。

静态导入并传递变量

---
- hosts: webservers
  tasks:
    - name: Import the foo_app_instance role
      ansible.builtin.import_role:
        name: foo_app_instance
      vars:
        dir: '/opt/a'
        app_port: 5000
  # ...

四、角色参数校验

从 Ansible 2.11 起，可以用参数规范启用角色参数校验。规范放在 meta/argument_specs.yml，也支持 .yaml 扩展名。定义后，Ansible 会在角色执行起点插入校验任务，把传入参数与规范比较；校验不通过时，角色执行失败。

规范也可放在 meta/main.yml，但采用这种布局的角色不能在低于 2.11 的版本使用。为兼顾旧版本，原文建议使用单独的 meta/argument_specs.yml。若角色有依赖，依赖角色的参数验证先于当前角色进行，即使当前角色稍后校验失败也一样。自动插入的参数校验任务带 always 标签；静态导入时，它会执行，除非通过 --skip-tags 排除。

参数规范的格式

文件顶层必须是 argument_specs，所有字段名都使用小写。argument_specs 下每个键表示一个角色入口，随后描述该入口及其 options。

入口字段	要求
entry-point-name	入口名称；默认入口为 main，对应任务文件的基本名，不含 .yml/.yaml。
short_description	一行短描述，最好是短语，不以句号结束；必须是字符串，不能是列表。会出现在 ansible-doc -t role -l 以及角色文档标题中，支持 Ansible markup。
description	较长的描述，可以是字符串或字符串列表；列表每项成为一个段落，支持 Ansible markup。
version_added	入口新增时的角色版本，以字符串表示，例如 ‘2.1’，不能误写成浮点数；collection 中填写新增入口的 collection 版本，例如 1.0.0。
author	入口作者，使用单个字符串或字符串列表；多人时每人一项。
options	入口参数定义；每个键是参数名称，其下定义数据类型、默认值和其他约束。

参数字段	要求
description	用完整句子解释参数；字符串或字符串列表均可，列表每项是一个段落，支持 Ansible markup。
version_added	仅在参数晚于角色/入口初次发布时需要；字符串格式，collection 中填写 collection 版本。
type	参数数据类型，默认 str；允许值以 Argument spec 参考为准。list 应同时给出 elements。
required	仅在 true 时有必要写出；省略表示非必需。
default	required 为 false 或省略时可填写，省略默认视为 null；必须与角色 defaults 中实际默认值一致。规范中的 default 不会取代角色 defaults 的运行时默认值。
choices	可选值列表；没有可选值限制时不要写空列表。
elements	type 为 list 时，其列表元素的数据类型。
options	字典或字典列表的嵌套结构定义。

default 不应重复写进说明文字，除非需要补充适用条件。布尔值使用 true/false，以兼容 ansible-lint。类型校验是“可转换即通过”的校验：传入整数 1，而规范要求字符串，也可能通过验证；然而角色真正拿到的仍是原始整数 1，并非字符串 "1"。需要固定类型时，在角色逻辑中显式使用 | string、| bool 等过滤器。

完整参数规范示例

下面保留原文的完整 myapp 示例：main 入口覆盖整数、字符串、字符串列表、带默认值的字典列表和带子选项的字典；alternate 入口展示另一个任务文件及不同默认值。示例中的作者 Daniel Ziegenberg 是该参数示例的署名，不应据此误认其为整个文档的唯一作者。

roles/myapp/meta/argument_specs.yml：包括全部嵌套 options 与 alternate 入口

# roles/myapp/meta/argument_specs.yml
---
argument_specs:
  # roles/myapp/tasks/main.yml entry point
  main:
    short_description: Main entry point for the myapp role
    description:
      - This is the main entrypoint for the C(myapp) role.
      - Here we can describe what this entrypoint does in lengthy words.
      - Every new list item is a new paragraph. You can have multiple sentences
        per paragraph.
    author:
      - Daniel Ziegenberg
    options:
      myapp_int:
        type: "int"
        required: false
        default: 42
        description:
          - "The integer value, defaulting to 42."
          - "This is a second paragraph."

      myapp_str:
        type: "str"
        required: true
        description: "The string value"

      myapp_list:
        type: "list"
        elements: "str"
        required: true
        description: "A list of string values."
        version_added: 1.3.0

      myapp_list_with_dicts:
        type: "list"
        elements: "dict"
        required: false
        default:
          - myapp_food_kind: "meat"
            myapp_food_boiling_required: true
            myapp_food_preparation_time: 60
          - myapp_food_kind: "fruits"
            myapp_food_preparation_time: 5
        description: "A list of dicts with a defined structure and with a default value."
        options:
          myapp_food_kind:
            type: "str"
            choices:
              - "vegetables"
              - "fruits"
              - "grains"
              - "meat"
            required: false
            description: "A string value with a limited list of allowed choices."

          myapp_food_boiling_required:
            type: "bool"
            required: false
            default: false
            description: "Whether the kind of food requires boiling before consumption."

          myapp_food_preparation_time:
            type: int
            required: true
            description: "Time to prepare a dish in minutes."

      myapp_dict_with_suboptions:
        type: "dict"
        required: false
        default:
          myapp_host: "bar.foo"
          myapp_exclude_host: true
          myapp_path: "/etc/myapp"
        description: "A dict with a defined structure and default values."
        options:
          myapp_host:
            type: "str"
            choices:
              - "foo.bar"
              - "bar.foo"
              - "ansible.foo.bar"
            required: true
            description: "A string value with a limited list of allowed choices."

          myapp_exclude_host:
            type: "bool"
            required: true
            description: "A boolean value."

          myapp_path:
            type: "path"
            required: true
            description: "A path value."

          original_name:
            type: list
            elements: "str"
            required: false
            description: "An optional list of string values."

  # roles/myapp/tasks/alternate.yml entry point
  alternate:
    short_description: Alternate entry point for the myapp role
    description:
      - This is the alternate entrypoint for the C(myapp) role.
    version_added: 1.2.0
    options:
      myapp_int:
        type: "int"
        required: false
        default: 1024
        description: "The integer value, defaulting to 1024."

五、在同一个 play 多次运行角色

在 play 级 roles 复用中，即使一个角色被列出多次，Ansible 默认也只执行一次，除非各次角色定义具有不同参数。以下列表中的 foo 只执行一次：

默认去重的角色调用

---
- hosts: webservers
  roles:
    - foo
    - bar
    - foo

要强制重复，有两种常用方式。第一种是传递不同的角色参数。改变变量值不等同于改变角色参数；这种示例必须使用 roles，因为 import_role 和 include_role 不接受这里所说的角色参数写法。

内联映射形式：不同 message 使 foo 执行两次

---
- hosts: webservers
  roles:
    - { role: foo, message: "first" }
    - { role: foo, message: "second" }

展开映射形式：与上一例等效

---
- hosts: webservers
  roles:
    - role: foo
      message: "first"
    - role: foo
      message: "second"

第二种方式是在需要重复执行的角色 meta/main.yml 中设置 allow_duplicates: true。此时即使两次条目相同，foo 也会执行两次。

显式允许角色重复

# playbook.yml
---
- hosts: webservers
  roles:
    - foo
    - foo

# roles/foo/meta/main.yml
---
allow_duplicates: true

六、角色依赖

角色依赖会在使用当前角色时自动带入其他角色。这里的 dependency 更准确地说是执行先决条件：角色之间并不存在真正的父子关系；包括依赖列表中角色在内，所有角色的父对象都是 play。Ansible 载入列出的角色，先执行 dependencies，再执行声明依赖的角色。

依赖放在角色目录 meta/main.yml 中，内容是应先执行的角色及其参数列表：

myapp 对 common、apache 和 postgres 的依赖

# roles/myapp/meta/main.yml
---
dependencies:
  - role: common
    vars:
      some_parameter: 3
  - role: apache
    vars:
      apache_port: 80
  - role: postgres
    vars:
      dbname: blarg
      other_parameter: 12

使用 roles 关键字时，依赖按递归顺序处理。如果 foo 依赖 bar，而 bar 依赖 baz，实际次序就是 baz、bar、foo。

让依赖重复执行

依赖与 roles 列表使用类似的去重逻辑。两个角色都依赖同一个角色时，默认只运行这项依赖一次；若参数、标签或 when 条件不同，或者在需重复的角色上设置 allow_duplicates: true，则可能重复执行。去重不参考父角色的调用签名。

原文特别提醒：在依赖示例中，用 vars 代替角色参数会改变变量作用域。如果把下面各次 n 的参数改写成 vars，可能使 n 在整个 play 中都成为 4，包括较早调用的角色。去重还发生在变量求值之前，因此惰性求值可能让看似不同的调用被视为相同。不要仅凭最终值判断两个角色调用一定不同。

例如，car 依赖四个参数不同的 wheel：

car 的 meta/main.yml

---
dependencies:
  - role: wheel
    n: 1
  - role: wheel
    n: 2
  - role: wheel
    n: 3
  - role: wheel
    n: 4

wheel 又依赖 tire 和 brake：

wheel 的 meta/main.yml

---
dependencies:
  - role: tire
  - role: brake

在 tire 和 brake 各自的 meta/main.yml 中允许重复：

tire 与 brake 的元数据

---
allow_duplicates: true

由此得到的顺序如下：每个 wheel 前都有其 tire 和 brake，最后才运行 car。

示意执行顺序，省略号表示其余车轮按相同规则继续

tire(n=1)
brake(n=1)
wheel(n=1)
tire(n=2)
brake(n=2)
wheel(n=2)
...
car

allow_duplicates 应写在 dependencies 所引用、希望重复执行的角色中，而不是写在引用它的父级角色中。本例 wheel 自身无需该开关，因为 car 已经为每次 wheel 传入不同的 n。去重仅发生在一个 play 内；同一 playbook 中不同 play 可以再次执行同一角色。

七、在独立角色中嵌入模块和插件

这一机制仅适用于独立角色。collection 中的角色不支持这样嵌入插件，应使用 collection 的 plugins 结构分发。对于内部软件的专用模块，可以把模块随角色分发，从而不必让每个使用者手工配置 Ansible 的模块库路径。

自定义模块放在与 tasks、handlers 同级的 library 目录。下例角色提供 module1 和 module2：

在 library 中放置自定义模块

roles/
    my_custom_modules/
        library/
            module1
            module2

这些模块可用于该角色自身，也可用于随后调用的角色：

先载入模块角色，再使用其模块

---
- hosts: webservers
  roles:
    - my_custom_modules
    - some_other_role_using_my_custom_modules
    - yet_another_role_using_my_custom_modules

必要时也能把 Ansible 核心模块的修改版嵌入角色，例如在正式发行前使用开发版实现。原文明确要求谨慎：核心 API 签名可能变化，这种临时方法没有兼容性保证。

插件按对应的插件目录结构分发。例如过滤器插件放在 filter_plugins：

分发自定义过滤器

roles/
    my_custom_filter/
        filter_plugins
            filter1
            filter2

在 my_custom_filter 之后调用的角色，就可以在 Jinja 模板中使用这些过滤器。模块和插件是代码执行边界；应确认来源和实际逻辑，再赋予主机操作权限。

八、通过 Ansible Galaxy 分享角色

Ansible Galaxy 提供社区角色的查找、下载、评分与评审。Ansible 自带 ansible-galaxy 客户端，既可下载角色，也为新角色生成默认结构。创建、发布和管理角色的进一步细节应查阅 Galaxy 用户指南。

继续学习时，可以沿原文引用查阅 YAML 语法、playbook 基础、变量、条件、循环、标签和 collection 索引；开发自定义功能时阅读模块与插件开发指南；交流问题则使用 Ansible 社区沟通渠道。角色复用不会自动保证幂等性、安全性或跨版本兼容，真正上线前仍需以实际环境验证。

来源、署名与许可

原文版权归 Ansible 项目贡献者；文档源码仓库 COPYING 采用 GNU General Public License version 3（GPL-3.0）。本中文译写保留原署名、来源与GPL-3.0许可；改编内容按相同许可提供。完整许可附于本文末尾，并保留原 COPYING 链接。

代码保留原有技术结构，英文标识符、代码注释和演示文本保留，编者补充已明确标注。原创流程图用于解释正文，不代表实测结果。

版权与许可全文

以下保留本页涉及的来源材料或示例代码的版权、许可条件与免责声明；各自适用范围依原声明。中文翻译及编辑标注：未完纪，2026-10-05。

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combination as such.

  14. Revised Versions of this License.

  The Free Software Foundation may publish revised and/or new versions of
the GNU General Public License from time to time.  Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.

  Each version is given a distinguishing version number.  If the
Program specifies that a certain numbered version of the GNU General
Public License "or any later version" applies to it, you have the
option of following the terms and conditions either of that numbered
version or of any later version published by the Free Software
Foundation.  If the Program does not specify a version number of the
GNU General Public License, you may choose any version ever published
by the Free Software Foundation.

  If the Program specifies that a proxy can decide which future
versions of the GNU General Public License can be used, that proxy's
public statement of acceptance of a version permanently authorizes you
to choose that version for the Program.

  Later license versions may give you additional or different
permissions.  However, no additional obligations are imposed on any
author or copyright holder as a result of your choosing to follow a
later version.

  15. Disclaimer of Warranty.

  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
ALL NECESSARY SERVICING, REPAIR OR CORRECTION.

  16. Limitation of Liability.

  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES.

  17. Interpretation of Sections 15 and 16.

  If the disclaimer of warranty and limitation of liability provided
above cannot be given local legal effect according to their terms,
reviewing courts shall apply local law that most closely approximates
an absolute waiver of all civil liability in connection with the
Program, unless a warranty or assumption of liability accompanies a
copy of the Program in return for a fee.

                     END OF TERMS AND CONDITIONS

            How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
state the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.

Also add information on how to contact you by electronic and paper mail.

  If the program does terminal interaction, make it output a short
notice like this when it starts in an interactive mode:

    <program>  Copyright (C) <year>  <name of author>
    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, your program's commands
might be different; for a GUI interface, you would use an "about box".

  You should also get your employer (if you work as a programmer) or school,
if any, to sign a "copyright disclaimer" for the program, if necessary.
For more information on this, and how to apply and follow the GNU GPL, see
<https://www.gnu.org/licenses/>.

  The GNU General Public License does not permit incorporating your program
into proprietary programs.  If your program is a subroutine library, you
may consider it more useful to permit linking proprietary applications with
the library.  If this is what you want to do, use the GNU Lesser General
Public License instead of this License.  But first, please read
<https://www.gnu.org/licenses/why-not-lgpl.html>.

文章版权归作者所有，未经允许请勿转载。

THE END