第 11 章 数据转换

	提示
	iconv(1) 是 libc6 软件包的一部分并且它可以在类 Unix 的系统上转换字符的编码。

你能够通过如下的命令用 iconv(1) 来转换文本文件的编码。

$ iconv -f encoding1 -t encoding2 input.txt >output.txt

Encoding values are case insensitive and ignore "-" and "_" for matching. Supported encodings can be checked by the "iconv -l" command.

	注意
	一些编码只支持数据转换，它不能作为语言环境的值 (第 8.3.1 节 “编码的基础知识”)。

像 ASCII 和 ISO-8859 这样适用于单字节的字符集，字符编码和字符集几乎指的是同一件事情。

For character sets with many characters such as JIS X 0213 for Japanese or Universal Character Set (UCS, Unicode, ISO-10646-1) for practically all languages, there are many encoding schemes to fit them into the sequence of the byte data.

对于以上这些，字符集和字符编码之间有着明显的区别。

The code page is used as the synonym to the character encoding tables for some vendor specific ones.

注意

Please note most encoding systems share the same code with ASCII for the 7 bit characters. But there are some exceptions. If you are converting old Japanese C programs and URLs data from the casually-called shift-JIS encoding format to UTF-8 format, use "CP932" as the encoding name instead of "shift-JIS" to get the expected results: 0x5C → "\" and 0x7E → "~". Otherwise, these are converted to wrong characters.

	提示
	recode(1) 也可能被使用并且不仅仅是 iconv(1)，fromdos(1)，todos(1)，frommac(1) 和 tomac(1) 功能的结合。想要获得更多信息，请参见 "info recode"。

#!/bin/sh
ENCDN=iso-8859-1
for x in *;
 do
 mv "$x" "$(echo "$x" | iconv -f $ENCDN -t utf-8)"
done

The "$ENCDN" variable specifies the original encoding used for file names under older OS as in 表 11.2 “编码值和用法的列表”.

For more complicated case, please mount a filesystem (e.g. a partition on a disk drive) containing such file names with proper encoding as the mount(8) option (see 第 8.3.6 节 “文件名编码”) and copy its entire contents to another filesystem mounted as UTF-8 with "cp -a" command.

$ vim u-file.txt

$ vim '+e ++enc=latin2 pu-file.txt'

$ vim '+e ++enc=eucJP ju-file.txt'

$ vim '+e ++enc=CP932 ++ff=dos jw-file.txt'

Please refer to the mbyte.txt "multi-byte text support" in vim on-line help and 表 11.2 “编码值和用法的列表” for locale values used with "++enc".

The emacs family of programs can perform the equivalent functions.

XML text looks somewhat like HTML. It enables us to manage multiple formats of output for a document. One easy XML system is the docbook-xsl package, which is used here.

Each XML file starts with standard XML declaration as the following.

<?xml version="1.0" encoding="UTF-8"?>

The basic syntax for one XML element is marked up as the following.

<name attribute="value">content</name>

XML element with empty content is marked up in the following short form.

<name attribute="value"/>

The "attribute="value"" in the above examples are optional.

The comment section in XML is marked up as the following.

<!-- comment -->

Other than adding markups, XML requires minor conversion to the content using predefined entities for following characters.

	小心
	"<" or "&" can not be used in attributes or elements.

	注意
	When SGML style user defined entities, e.g. "&some-tag:", are used, the first definition wins over others. The entity definition is expressed in "<!ENTITY some-tag "entity value">".

	注意
	As long as the XML markup are done consistently with certain set of the tag name (either some data as content or attribute value), conversion to another XML is trivial task using Extensible Stylesheet Language Transformations (XSLT).

There are many tools available to process XML files such as the Extensible Stylesheet Language (XSL).

Basically, once you create well formed XML file, you can convert it to any format using Extensible Stylesheet Language Transformations (XSLT).

The Extensible Stylesheet Language for Formatting Objects (XSL-FO) is supposed to be solution for formatting. The fop package is new to the Debian main archive due to its dependence to the Java programing language. So the LaTeX code is usually generated from XML using XSLT and the LaTeX system is used to create printable file such as DVI, PostScript, and PDF.

Since XML is subset of Standard Generalized Markup Language (SGML), it can be processed by the extensive tools available for SGML, such as Document Style Semantics and Specification Language (DSSSL).

	提示
	GNOME's yelp is sometimes handy to read DocBook XML files directly since it renders decently on X.

传统意义上，roff 是 Unix 上主要的文本处理系统。参见 roff(7), groff(7), groff(1), grotty(1), troff(1), groff_mdoc(7), groff_man(7), groff_ms(7), groff_me(7), groff_mm(7) 和 "info groff"。

You can read or print a good tutorial and reference on "-me" macro in "/usr/share/doc/groff/" by installing the groff package.

	提示
	"groff -Tascii -me -" produces plain text output with ANSI escape code. If you wish to get manpage like output with many "^H" and "_", use "GROFF_NO_SGR=1 groff -Tascii -me -" instead.

	提示
	To remove "^H" and "_" from a text file generated by groff, filter it by "col -b -x".

The TeX Live software distribution offers a complete TeX system. The texlive metapackage provides a decent selection of the TeX Live packages which should suffice for the most common tasks.

这里有许多可用的 TeX 和 LaTeX 的参考资料。

This is the most powerful typesetting environment. Many SGML processors use this as their back end text processor. Lyx provided by the lyx package and GNU TeXmacs provided by the texmacs package offer nice WYSIWYG editing environment for LaTeX while many use Emacs and Vim as the choice for the source editor.

有许多在线资源存在。

When documents become bigger, sometimes TeX may cause errors. You must increase pool size in "/etc/texmf/texmf.cnf" (or more appropriately edit "/etc/texmf/texmf.d/95NonPath" and run update-texmf(8)) to fix this.

注意

The TeX source of "The TeXbook" is available at http://tug.ctan.org/tex-archive/systems/knuth/dist/tex/texbook.tex. This file contains most of the required macros. I heard that you can process this document with tex(1) after commenting lines 7 to 10 and adding "\input manmac \proofmodefalse". It's strongly recommended to buy this book (and all other books from Donald E. Knuth) instead of using the online version but the source is a great example of TeX input!

尽管用纯 troff 格式写手册页（manpage）是可能的，这里还是有一些辅助的程序包用于创建手册页。

处理可印刷的数据的核心是 Ghostscript PostScript 解释器，它能够生成光栅图像。

The latest upstream Ghostscript from Artifex was re-licensed from AFPL to GPL and merged all the latest ESP version changes such as CUPS related ones at 8.60 release as unified release.

	提示
	"gs -h" 能够显示 Ghostscript 的配置信息。

你能够使用 Ghostscript 中的 gs(1) 来合并两个 PostScript(PS) 或可移植文档格式（PDF） 文件。

$ gs -q -dNOPAUSE -dBATCH -sDEVICE=pswrite -sOutputFile=bla.ps -f foo1.ps foo2.ps
$ gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=bla.pdf -f foo1.pdf foo2.pdf

	注意
	PDF 是用途很广的跨平台可印刷的数据格式，它本质上是带有一些额外特性和扩展的压缩了的 PS 格式。

	提示
	对于命令行来说，psmerge(1) 和 psutils 包中的其他命令在处理 PostScript 文档时是很有用的。pdftk 包中的 pdftk(1) 在处理 PDF 文档的时候同样是很好用的。

Unix 通用打印系统（CUPS） 中的 lp(1) 和 lpr(1) 命令都提供了自定义打印数据的选项。

你可以使用下列命令中的一个来打印 3 份有装订页码的文件。

$ lp -n 3 -o Collate=True filename

$ lpr -#3 -o Collate=True filename

你能够通过 "-o number-up=2", "-o page-set=even", "-o page-set=odd", "-o scaling=200", "-o natural-scaling=200" 等等打印机选项来进一步定制打印机操作，详细的文档参见命令行打印和选项。

邮件 (SMTP) 数据需要被限制为 7 位数据序列。二进制数据和 8 位文本数据使用 Multipurpose Internet Mail Extensions (MIME) 互联网多用途邮件扩展 和选择的字符集编码到 7 位格式。(参见 第 8.3.1 节 “编码的基础知识”).

标准的邮件存储格式是 mbox，它是依据 RFC2822 (由 RFC822 更新) 来的格式. 参见 mbox(5) (由 mutt 软件包提供).

对于欧洲语言,由于没有什么 8 位字符，"Content-Transfer-Encoding: quoted-printable" 加 ISO-8859-1 字符集通常被用于邮件。如果欧洲文本是被编码为 UTF-8,由于几乎全是 7 位数据，使用 "Content-Transfer-Encoding: quoted-printable" 也是合适的。

对于日语，传统的 "Content-Type: text/plain; charset=ISO-2022-JP" 通常被用于邮件来保持文本在 7 位。但是老的微软系统会在没有声明的情况下使用 Shift-JIS 来发送邮件。如果日语文本是用 UTF-8 编码, 由于含有许多 8 位数据，使用 Base64 是合适的。其它亚洲语言也是类似情形。

	注意
	如果你的非 Unix 邮件数据可以通过一个具备和 IMAP4 服务通讯的非 Debian 客户端访问，你可以通过运行你的 IMAP4 服务来将邮件数据移出。(参见 第 6.7 节 “POP3/IMAP4 服务器”).

	注意
	如果你使用其它邮件存储格式，第一步把它们移动到 mbox 格式比较好。像 mutt(1) 这样多功能的客户端程序可以便捷的完成这类操作。

你可以使用 procmail(1) 和 formail(1) 把邮箱内容分开成每一封邮件.

每一封邮件能够使用来自 mpack 软件包的 munpack(1) 命令（或其它特异的工具）来获得 MIME 编码内容。