---
hackpadID: b6y4uC6HCCw
hackpadWorkspace: tossug
tags: hackpad-import, tossug
---
# Linux 讀書會 - 第 11 週 10/14/2014

總目錄 [edX Introduction to Linux](https://tossug.hackpad.com/dVX1LvoCcii)

## 課程筆記

**Chapter 14: Printing**

<undefined>* **Common UNIX Printing System (CUPS)**</undefined>

Concentrating more on printing and less on how to print

* Configuration Files
* /etc/cups/cupsd.conf -> system-wide settings
* /etc/cups/printers.conf -> printer-specific settings
* Scheduler
* manage print jobs
* handle administrative commands
* allow user to query status (browser based interface)
* manage flow of data through all CUPS components
* Job Files
* Log Files
* Filter
* Printer Drivers
* Backend


**CUPS** stores print requests as files under the `/var/spool/cups` directory.

These data files belong to what is commonly known as the **print queue**.

Log files are placed in `/var/log/cups` and are used by the scheduler to record activities that have taken place.

**Chapter 15: Bash Shell Scripting**

[Shell](https://en.wikipedia.org/wiki/Shell_(computing)) 提供使用者操作系統核心 (Core) 的介面，涵蓋範圍包括但不限於：

* CLI
* GUI

<undefined>* **CLI**</undefined>


* ash: 輕量級的 shell，符合 POSIX 標準，許多 UNIX 系統的預設 shell。
* Dash: 基於 ash，功能較完整，未完全相容 Bash。
* Zsh: [](http://www.zsh.org/)http://www.zsh.org/
* fish: [](http://fishshell.com/)[http://fishshell.com/](http://fishshell.com/)
* Xikishell: [](http://xsh.org/)[http://xsh.org/](http://xsh.org/)
* IPython: [](http://ipython.org/)[http://ipython.org/](http://ipython.org/)
* Eshell: [](http://www.gnu.org/software/emacs/manual/html_node/eshell/)[http://www.gnu.org/software/emacs/manual/html_node/eshell/](http://www.gnu.org/software/emacs/manual/html_node/eshell/)
* OpenSSH: [](http://www.openssh.com/)[http://www.openssh.com/](http://www.openssh.com/)
* MS-DOS Shell
* Command Prompt（命令提示字元）
* Windows PowerShell

<undefined>* **GUI**</undefined>

* IPython Notebook
* Windows Explorer
* X Window System
* Wayland
* Mir

<undefined>* **Section 1: Features and Capabilities**</undefined>

**shell script** 是一連串 shell 指令的集合，Linux 底下最常使用 Bash。

Linux 系統的 sh 通常指到 Bash，但也有可能指到 dash 或 ash，因此在撰寫 shell script 時，[應該在 script 第一行聲明](https://en.wikipedia.org/wiki/Shebang_(Unix) )。

<undefined>* **Section 3: Constructs**</undefined>

* doubled brackets [](http://mywiki.wooledge.org/BashFAQ/031)http://mywiki.wooledge.org/BashFAQ/031
* Not portable, only in Bash, Zsh and Korn shell
* Arguments need not be quoted while contianing whitespace
* Parentheses do not need to be escaped

由本章節主要探討 Bash Shell Scripting，實務上我們主要也會是寫 Bash，相容性的問題不必理會。

<undefined>* **重點回顧**</undefined>

* 最基本的 Linux Base System 都會有 Bash。
* 客製化或非 Linux 系統不在此限。
* 若您需要相容 ash，建議一開始就用 ash。
* ash 功能比 Bash 精簡很多，可以視為是 Bash 子集。
* 不建議直接使用 sh，請指定 shell 類型。
* 每個系統的 sh 不一定是 Bash，可能指到別的 shell。
* 即便語法可能相容，若沒測過，執行結果無法預期。
* 熟悉 Shell Scripting 需要多看多練習。
* 參考別人的 shell script 就是一種入門捷徑。
* Shell Script 可視為是一種字串取代的過程。
* function 回傳值只要呼叫 echo 即可。
* Shell Script 可以 import / include。
* 您可以把程式拆成許多函式庫和模組。
* Defensive Programming 有助於減少錯誤。
* 條件判斷可以轉成 function，搭配 `&&` 和 `||` 操作。

<undefined>* **參考資料**</undefined>

Linux Standard Base (LSB) Referenced Specifications

[](http://refspecs.linuxfoundation.org/lsb.shtml)http://refspecs.linuxfoundation.org/lsb.shtml

Defensive BASH Programming

[](http://www.kfirlavi.com/blog/2012/11/14/defensive-bash-programming/)http://www.kfirlavi.com/blog/2012/11/14/defensive-bash-programming/

shUnit2

[](https://code.google.com/p/shunit2/)https://code.google.com/p/shunit2/

Bash Debugger

[](http://bashdb.sourceforge.net/)http://bashdb.sourceforge.net/

## 本週作業

* Review Chapter 15: Bash Shell Scripting
* Study Chapter 16: Advanced Bash Scripting

## 活動簽到

[Carl Su](/ep/profile/n5euV0AaWLn)

[Bruce Tsai](/ep/profile/oLLqeaQgDjg)

[steven huang](/ep/profile/sncZfUbLaeE)

[P Fisher](/ep/profile/oTOWRrYfPRk)

[Sam Lu](/ep/profile/zi86w39M6U6)

[violetson](/ep/profile/oJusv72f72w)