# 第三部分 shell进阶

## 目录

* [9. 换个角度看变量](https://wiki.clay-wangzhi.com/shell/part3/09_another_look_at_variables)
  * [9.1 内部变量](https://wiki.clay-wangzhi.com/shell/part3/09_another_look_at_variables/09_1_internal_variables)
  * [9.2 变量类型标注：`declare` 与 `typeset`](https://wiki.clay-wangzhi.com/shell/part3/09_another_look_at_variables/09_2_typing_variables_declare_or_typeset)
    * [9.2.1 `declare` 的另类用法](https://wiki.clay-wangzhi.com/shell/part3/09_another_look_at_variables/09_2_typing_variables_declare_or_typeset/09_2_1_another_use_for_declare)
  * [9.3 `$RANDOM`：生成随机数](https://wiki.clay-wangzhi.com/shell/part3/09_another_look_at_variables/09_3_random_generate_random_integer)
* [10. 变量处理](https://wiki.clay-wangzhi.com/shell/part3/10_manipulating_variables)
  * [10.1 字符串处理](https://wiki.clay-wangzhi.com/shell/part3/10_manipulating_variables/10_1_manipulating_strings)
    * [10.1.1 使用 `awk` 处理字符串](https://wiki.clay-wangzhi.com/shell/part3/10_manipulating_variables/10_1_manipulating_strings/10_1_1_manipulating_strings_using_awk)
    * [10.1.2 参考资料](https://wiki.clay-wangzhi.com/shell/part3/10_manipulating_variables/10_1_manipulating_strings/10_1_2_further_reference)
  * [10.2 参数替换](https://wiki.clay-wangzhi.com/shell/part3/10_manipulating_variables/10_2_parameter_substitution)
* [11. 循环与分支](https://wiki.clay-wangzhi.com/shell/part3/11_loops_and_branches)
  * [11.1 循环](https://wiki.clay-wangzhi.com/shell/part3/11_loops_and_branches/11_1_loops)
  * [11.2 嵌套循环](https://wiki.clay-wangzhi.com/shell/part3/11_loops_and_branches/11_2_nested_loops)
  * [11.3 循环控制](https://wiki.clay-wangzhi.com/shell/part3/11_loops_and_branches/11_3_loop_control)
  * [11.4 测试与分支](https://wiki.clay-wangzhi.com/shell/part3/11_loops_and_branches/11_4_testing_and_branching)
* [12. 命令替换](https://wiki.clay-wangzhi.com/shell/part3/12_command_substitution)
* [13. 算术扩展](https://wiki.clay-wangzhi.com/shell/part3/13_arithmetic_expansion)
* [14. 休息时间](https://wiki.clay-wangzhi.com/shell/broken-reference)