1178 lines
34 KiB
HTML
1178 lines
34 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
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"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
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<head>
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<meta http-equiv="Content-Type" content="application/xhtml+xml; charset=UTF-8" />
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<meta name="generator" content="AsciiDoc 10.2.0" />
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<title>gittutorial-2(7)</title>
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<style type="text/css">
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/* Shared CSS for AsciiDoc xhtml11 and html5 backends */
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/* Default font. */
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body {
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font-family: Georgia,serif;
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}
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/* Title font. */
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h1, h2, h3, h4, h5, h6,
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div.title, caption.title,
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thead, p.table.header,
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#toctitle,
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#author, #revnumber, #revdate, #revremark,
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#footer {
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font-family: Arial,Helvetica,sans-serif;
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}
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body {
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margin: 1em 5% 1em 5%;
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}
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a {
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color: blue;
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text-decoration: underline;
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}
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a:visited {
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color: fuchsia;
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}
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em {
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font-style: italic;
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color: navy;
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}
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strong {
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font-weight: bold;
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color: #083194;
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}
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h1, h2, h3, h4, h5, h6 {
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color: #527bbd;
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margin-top: 1.2em;
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margin-bottom: 0.5em;
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line-height: 1.3;
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}
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h1, h2, h3 {
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border-bottom: 2px solid silver;
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}
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h2 {
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padding-top: 0.5em;
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}
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h3 {
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float: left;
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}
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h3 + * {
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clear: left;
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}
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h5 {
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font-size: 1.0em;
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}
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div.sectionbody {
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margin-left: 0;
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}
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hr {
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border: 1px solid silver;
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}
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p {
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margin-top: 0.5em;
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margin-bottom: 0.5em;
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}
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ul, ol, li > p {
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margin-top: 0;
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}
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ul > li { color: #aaa; }
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ul > li > * { color: black; }
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.monospaced, code, pre {
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font-family: "Courier New", Courier, monospace;
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font-size: inherit;
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color: navy;
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padding: 0;
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margin: 0;
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}
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pre {
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white-space: pre-wrap;
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}
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#author {
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color: #527bbd;
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font-weight: bold;
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font-size: 1.1em;
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}
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#email {
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}
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#revnumber, #revdate, #revremark {
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}
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#footer {
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font-size: small;
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border-top: 2px solid silver;
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padding-top: 0.5em;
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margin-top: 4.0em;
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}
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#footer-text {
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float: left;
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padding-bottom: 0.5em;
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}
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#footer-badges {
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float: right;
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padding-bottom: 0.5em;
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}
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#preamble {
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margin-top: 1.5em;
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margin-bottom: 1.5em;
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}
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div.imageblock, div.exampleblock, div.verseblock,
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div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
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div.admonitionblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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div.admonitionblock {
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margin-top: 2.0em;
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margin-bottom: 2.0em;
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margin-right: 10%;
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color: #606060;
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}
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div.content { /* Block element content. */
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padding: 0;
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}
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/* Block element titles. */
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div.title, caption.title {
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color: #527bbd;
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font-weight: bold;
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text-align: left;
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margin-top: 1.0em;
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margin-bottom: 0.5em;
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}
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div.title + * {
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margin-top: 0;
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}
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td div.title:first-child {
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margin-top: 0.0em;
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}
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div.content div.title:first-child {
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margin-top: 0.0em;
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}
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div.content + div.title {
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margin-top: 0.0em;
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}
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div.sidebarblock > div.content {
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background: #ffffee;
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border: 1px solid #dddddd;
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border-left: 4px solid #f0f0f0;
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padding: 0.5em;
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}
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div.listingblock > div.content {
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border: 1px solid #dddddd;
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border-left: 5px solid #f0f0f0;
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background: #f8f8f8;
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padding: 0.5em;
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}
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div.quoteblock, div.verseblock {
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padding-left: 1.0em;
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margin-left: 1.0em;
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margin-right: 10%;
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border-left: 5px solid #f0f0f0;
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color: #888;
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}
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div.quoteblock > div.attribution {
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padding-top: 0.5em;
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text-align: right;
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}
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div.verseblock > pre.content {
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font-family: inherit;
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font-size: inherit;
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}
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div.verseblock > div.attribution {
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padding-top: 0.75em;
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text-align: left;
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}
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/* DEPRECATED: Pre version 8.2.7 verse style literal block. */
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div.verseblock + div.attribution {
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text-align: left;
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}
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div.admonitionblock .icon {
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vertical-align: top;
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font-size: 1.1em;
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font-weight: bold;
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text-decoration: underline;
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color: #527bbd;
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padding-right: 0.5em;
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}
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div.admonitionblock td.content {
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padding-left: 0.5em;
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border-left: 3px solid #dddddd;
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}
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div.exampleblock > div.content {
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border-left: 3px solid #dddddd;
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padding-left: 0.5em;
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}
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div.imageblock div.content { padding-left: 0; }
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span.image img { border-style: none; vertical-align: text-bottom; }
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a.image:visited { color: white; }
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dl {
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margin-top: 0.8em;
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margin-bottom: 0.8em;
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}
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dt {
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margin-top: 0.5em;
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margin-bottom: 0;
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font-style: normal;
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color: navy;
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}
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dd > *:first-child {
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margin-top: 0.1em;
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}
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ul, ol {
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list-style-position: outside;
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}
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ol.arabic {
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list-style-type: decimal;
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}
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ol.loweralpha {
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list-style-type: lower-alpha;
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}
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ol.upperalpha {
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list-style-type: upper-alpha;
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}
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ol.lowerroman {
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list-style-type: lower-roman;
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}
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ol.upperroman {
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list-style-type: upper-roman;
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}
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div.compact ul, div.compact ol,
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div.compact p, div.compact p,
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div.compact div, div.compact div {
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margin-top: 0.1em;
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margin-bottom: 0.1em;
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}
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tfoot {
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font-weight: bold;
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}
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td > div.verse {
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white-space: pre;
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}
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div.hdlist {
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margin-top: 0.8em;
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margin-bottom: 0.8em;
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}
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div.hdlist tr {
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padding-bottom: 15px;
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}
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dt.hdlist1.strong, td.hdlist1.strong {
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font-weight: bold;
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}
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td.hdlist1 {
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vertical-align: top;
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font-style: normal;
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padding-right: 0.8em;
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color: navy;
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}
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td.hdlist2 {
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vertical-align: top;
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}
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div.hdlist.compact tr {
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margin: 0;
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padding-bottom: 0;
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}
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.comment {
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background: yellow;
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}
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.footnote, .footnoteref {
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font-size: 0.8em;
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}
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span.footnote, span.footnoteref {
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vertical-align: super;
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}
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#footnotes {
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margin: 20px 0 20px 0;
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padding: 7px 0 0 0;
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}
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#footnotes div.footnote {
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margin: 0 0 5px 0;
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}
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#footnotes hr {
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border: none;
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border-top: 1px solid silver;
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height: 1px;
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text-align: left;
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margin-left: 0;
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width: 20%;
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min-width: 100px;
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}
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div.colist td {
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padding-right: 0.5em;
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padding-bottom: 0.3em;
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vertical-align: top;
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}
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div.colist td img {
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margin-top: 0.3em;
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}
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@media print {
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#footer-badges { display: none; }
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}
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#toc {
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margin-bottom: 2.5em;
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}
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#toctitle {
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color: #527bbd;
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font-size: 1.1em;
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font-weight: bold;
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margin-top: 1.0em;
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margin-bottom: 0.1em;
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}
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div.toclevel0, div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 {
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margin-top: 0;
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margin-bottom: 0;
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}
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div.toclevel2 {
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margin-left: 2em;
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font-size: 0.9em;
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}
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div.toclevel3 {
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margin-left: 4em;
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font-size: 0.9em;
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}
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div.toclevel4 {
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margin-left: 6em;
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font-size: 0.9em;
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}
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span.aqua { color: aqua; }
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span.black { color: black; }
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span.blue { color: blue; }
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span.fuchsia { color: fuchsia; }
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span.gray { color: gray; }
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span.green { color: green; }
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span.lime { color: lime; }
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span.maroon { color: maroon; }
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span.navy { color: navy; }
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span.olive { color: olive; }
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span.purple { color: purple; }
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span.red { color: red; }
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span.silver { color: silver; }
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span.teal { color: teal; }
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span.white { color: white; }
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span.yellow { color: yellow; }
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span.aqua-background { background: aqua; }
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span.black-background { background: black; }
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span.blue-background { background: blue; }
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span.fuchsia-background { background: fuchsia; }
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span.gray-background { background: gray; }
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span.green-background { background: green; }
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span.lime-background { background: lime; }
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span.maroon-background { background: maroon; }
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span.navy-background { background: navy; }
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span.olive-background { background: olive; }
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span.purple-background { background: purple; }
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span.red-background { background: red; }
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span.silver-background { background: silver; }
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span.teal-background { background: teal; }
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span.white-background { background: white; }
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span.yellow-background { background: yellow; }
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span.big { font-size: 2em; }
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span.small { font-size: 0.6em; }
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span.underline { text-decoration: underline; }
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span.overline { text-decoration: overline; }
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span.line-through { text-decoration: line-through; }
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div.unbreakable { page-break-inside: avoid; }
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/*
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* xhtml11 specific
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*
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* */
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div.tableblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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div.tableblock > table {
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border: 3px solid #527bbd;
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}
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thead, p.table.header {
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font-weight: bold;
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color: #527bbd;
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}
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p.table {
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margin-top: 0;
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}
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/* Because the table frame attribute is overridden by CSS in most browsers. */
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div.tableblock > table[frame="void"] {
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border-style: none;
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}
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div.tableblock > table[frame="hsides"] {
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border-left-style: none;
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border-right-style: none;
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}
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div.tableblock > table[frame="vsides"] {
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border-top-style: none;
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border-bottom-style: none;
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}
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/*
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* html5 specific
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*
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* */
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table.tableblock {
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margin-top: 1.0em;
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margin-bottom: 1.5em;
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}
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thead, p.tableblock.header {
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font-weight: bold;
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color: #527bbd;
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}
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p.tableblock {
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margin-top: 0;
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}
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table.tableblock {
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border-width: 3px;
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border-spacing: 0px;
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border-style: solid;
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border-color: #527bbd;
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border-collapse: collapse;
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}
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th.tableblock, td.tableblock {
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border-width: 1px;
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padding: 4px;
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border-style: solid;
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border-color: #527bbd;
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}
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table.tableblock.frame-topbot {
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border-left-style: hidden;
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border-right-style: hidden;
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}
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table.tableblock.frame-sides {
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border-top-style: hidden;
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border-bottom-style: hidden;
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}
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|
table.tableblock.frame-none {
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border-style: hidden;
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}
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|
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th.tableblock.halign-left, td.tableblock.halign-left {
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text-align: left;
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}
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|
th.tableblock.halign-center, td.tableblock.halign-center {
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text-align: center;
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}
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th.tableblock.halign-right, td.tableblock.halign-right {
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text-align: right;
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}
|
|
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|
th.tableblock.valign-top, td.tableblock.valign-top {
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|
vertical-align: top;
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|
}
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|
th.tableblock.valign-middle, td.tableblock.valign-middle {
|
|
vertical-align: middle;
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}
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|
th.tableblock.valign-bottom, td.tableblock.valign-bottom {
|
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vertical-align: bottom;
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}
|
|
|
|
|
|
/*
|
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* manpage specific
|
|
*
|
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* */
|
|
|
|
body.manpage h1 {
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padding-top: 0.5em;
|
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padding-bottom: 0.5em;
|
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border-top: 2px solid silver;
|
|
border-bottom: 2px solid silver;
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|
}
|
|
body.manpage h2 {
|
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border-style: none;
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|
}
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|
body.manpage div.sectionbody {
|
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margin-left: 3em;
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|
}
|
|
|
|
@media print {
|
|
body.manpage div#toc { display: none; }
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|
}
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|
|
|
|
|
</style>
|
|
<script type="text/javascript">
|
|
/*<+'])');
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// Function that scans the DOM tree for header elements (the DOM2
|
|
// nodeIterator API would be a better technique but not supported by all
|
|
// browsers).
|
|
var iterate = function (el) {
|
|
for (var i = el.firstChild; i != null; i = i.nextSibling) {
|
|
if (i.nodeType == 1 /* Node.ELEMENT_NODE */) {
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|
var mo = re.exec(i.tagName);
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|
if (mo && (i.getAttribute("class") || i.getAttribute("className")) != "float") {
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result[result.length] = new TocEntry(i, getText(i), mo[1]-1);
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}
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iterate(i);
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}
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}
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|
}
|
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iterate(el);
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return result;
|
|
}
|
|
|
|
var toc = document.getElementById("toc");
|
|
if (!toc) {
|
|
return;
|
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}
|
|
|
|
// Delete existing TOC entries in case we're reloading the TOC.
|
|
var tocEntriesToRemove = [];
|
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var i;
|
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for (i = 0; i < toc.childNodes.length; i++) {
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var entry = toc.childNodes[i];
|
|
if (entry.nodeName.toLowerCase() == 'div'
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&& entry.getAttribute("class")
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&& entry.getAttribute("class").match(/^toclevel/))
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tocEntriesToRemove.push(entry);
|
|
}
|
|
for (i = 0; i < tocEntriesToRemove.length; i++) {
|
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toc.removeChild(tocEntriesToRemove[i]);
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}
|
|
|
|
// Rebuild TOC entries.
|
|
var entries = tocEntries(document.getElementById("content"), toclevels);
|
|
for (var i = 0; i < entries.length; ++i) {
|
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var entry = entries[i];
|
|
if (entry.element.id == "")
|
|
entry.element.id = "_toc_" + i;
|
|
var a = document.createElement("a");
|
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/*]]>*/
|
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</script>
|
|
</head>
|
|
<body class="manpage">
|
|
<div id="header">
|
|
<h1>
|
|
gittutorial-2(7) Manual Page
|
|
</h1>
|
|
<h2>NAME</h2>
|
|
<div class="sectionbody">
|
|
<p>gittutorial-2 -
|
|
A tutorial introduction to Git: part two
|
|
</p>
|
|
</div>
|
|
</div>
|
|
<div id="content">
|
|
<div class="sect1">
|
|
<h2 id="_synopsis">SYNOPSIS</h2>
|
|
<div class="sectionbody">
|
|
<div class="verseblock">
|
|
<pre class="content">git *</pre>
|
|
<div class="attribution">
|
|
</div></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_description">DESCRIPTION</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>You should work through <a href="gittutorial.html">gittutorial(7)</a> before reading this tutorial.</p></div>
|
|
<div class="paragraph"><p>The goal of this tutorial is to introduce two fundamental pieces of
|
|
Git’s architecture—the object database and the index file—and to
|
|
provide the reader with everything necessary to understand the rest
|
|
of the Git documentation.</p></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_the_git_object_database">The Git object database</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>Let’s start a new project and create a small amount of history:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ mkdir test-project
|
|
$ cd test-project
|
|
$ git init
|
|
Initialized empty Git repository in .git/
|
|
$ echo 'hello world' > file.txt
|
|
$ git add .
|
|
$ git commit -a -m "initial commit"
|
|
[master (root-commit) 54196cc] initial commit
|
|
1 file changed, 1 insertion(+)
|
|
create mode 100644 file.txt
|
|
$ echo 'hello world!' >file.txt
|
|
$ git commit -a -m "add emphasis"
|
|
[master c4d59f3] add emphasis
|
|
1 file changed, 1 insertion(+), 1 deletion(-)</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>What are the 7 digits of hex that Git responded to the commit with?</p></div>
|
|
<div class="paragraph"><p>We saw in part one of the tutorial that commits have names like this.
|
|
It turns out that every object in the Git history is stored under
|
|
a 40-digit hex name. That name is the SHA-1 hash of the object’s
|
|
contents; among other things, this ensures that Git will never store
|
|
the same data twice (since identical data is given an identical SHA-1
|
|
name), and that the contents of a Git object will never change (since
|
|
that would change the object’s name as well). The 7 char hex strings
|
|
here are simply the abbreviation of such 40 character long strings.
|
|
Abbreviations can be used everywhere where the 40 character strings
|
|
can be used, so long as they are unambiguous.</p></div>
|
|
<div class="paragraph"><p>It is expected that the content of the commit object you created while
|
|
following the example above generates a different SHA-1 hash than
|
|
the one shown above because the commit object records the time when
|
|
it was created and the name of the person performing the commit.</p></div>
|
|
<div class="paragraph"><p>We can ask Git about this particular object with the <code>cat-file</code>
|
|
command. Don’t copy the 40 hex digits from this example but use those
|
|
from your own version. Note that you can shorten it to only a few
|
|
characters to save yourself typing all 40 hex digits:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git cat-file -t 54196cc2
|
|
commit
|
|
$ git cat-file commit 54196cc2
|
|
tree 92b8b694ffb1675e5975148e1121810081dbdffe
|
|
author J. Bruce Fields <bfields@puzzle.fieldses.org> 1143414668 -0500
|
|
committer J. Bruce Fields <bfields@puzzle.fieldses.org> 1143414668 -0500
|
|
|
|
initial commit</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>A tree can refer to one or more "blob" objects, each corresponding to
|
|
a file. In addition, a tree can also refer to other tree objects,
|
|
thus creating a directory hierarchy. You can examine the contents of
|
|
any tree using ls-tree (remember that a long enough initial portion
|
|
of the SHA-1 will also work):</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git ls-tree 92b8b694
|
|
100644 blob 3b18e512dba79e4c8300dd08aeb37f8e728b8dad file.txt</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Thus we see that this tree has one file in it. The SHA-1 hash is a
|
|
reference to that file’s data:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git cat-file -t 3b18e512
|
|
blob</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>A "blob" is just file data, which we can also examine with cat-file:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git cat-file blob 3b18e512
|
|
hello world</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Note that this is the old file data; so the object that Git named in
|
|
its response to the initial tree was a tree with a snapshot of the
|
|
directory state that was recorded by the first commit.</p></div>
|
|
<div class="paragraph"><p>All of these objects are stored under their SHA-1 names inside the Git
|
|
directory:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ find .git/objects/
|
|
.git/objects/
|
|
.git/objects/pack
|
|
.git/objects/info
|
|
.git/objects/3b
|
|
.git/objects/3b/18e512dba79e4c8300dd08aeb37f8e728b8dad
|
|
.git/objects/92
|
|
.git/objects/92/b8b694ffb1675e5975148e1121810081dbdffe
|
|
.git/objects/54
|
|
.git/objects/54/196cc2703dc165cbd373a65a4dcf22d50ae7f7
|
|
.git/objects/a0
|
|
.git/objects/a0/423896973644771497bdc03eb99d5281615b51
|
|
.git/objects/d0
|
|
.git/objects/d0/492b368b66bdabf2ac1fd8c92b39d3db916e59
|
|
.git/objects/c4
|
|
.git/objects/c4/d59f390b9cfd4318117afde11d601c1085f241</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>and the contents of these files is just the compressed data plus a
|
|
header identifying their length and their type. The type is either a
|
|
blob, a tree, a commit, or a tag.</p></div>
|
|
<div class="paragraph"><p>The simplest commit to find is the HEAD commit, which we can find
|
|
from .git/HEAD:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ cat .git/HEAD
|
|
ref: refs/heads/master</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>As you can see, this tells us which branch we’re currently on, and it
|
|
tells us this by naming a file under the .git directory, which itself
|
|
contains a SHA-1 name referring to a commit object, which we can
|
|
examine with cat-file:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ cat .git/refs/heads/master
|
|
c4d59f390b9cfd4318117afde11d601c1085f241
|
|
$ git cat-file -t c4d59f39
|
|
commit
|
|
$ git cat-file commit c4d59f39
|
|
tree d0492b368b66bdabf2ac1fd8c92b39d3db916e59
|
|
parent 54196cc2703dc165cbd373a65a4dcf22d50ae7f7
|
|
author J. Bruce Fields <bfields@puzzle.fieldses.org> 1143418702 -0500
|
|
committer J. Bruce Fields <bfields@puzzle.fieldses.org> 1143418702 -0500
|
|
|
|
add emphasis</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>The "tree" object here refers to the new state of the tree:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git ls-tree d0492b36
|
|
100644 blob a0423896973644771497bdc03eb99d5281615b51 file.txt
|
|
$ git cat-file blob a0423896
|
|
hello world!</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>and the "parent" object refers to the previous commit:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git cat-file commit 54196cc2
|
|
tree 92b8b694ffb1675e5975148e1121810081dbdffe
|
|
author J. Bruce Fields <bfields@puzzle.fieldses.org> 1143414668 -0500
|
|
committer J. Bruce Fields <bfields@puzzle.fieldses.org> 1143414668 -0500
|
|
|
|
initial commit</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>The tree object is the tree we examined first, and this commit is
|
|
unusual in that it lacks any parent.</p></div>
|
|
<div class="paragraph"><p>Most commits have only one parent, but it is also common for a commit
|
|
to have multiple parents. In that case the commit represents a
|
|
merge, with the parent references pointing to the heads of the merged
|
|
branches.</p></div>
|
|
<div class="paragraph"><p>Besides blobs, trees, and commits, the only remaining type of object
|
|
is a "tag", which we won’t discuss here; refer to <a href="git-tag.html">git-tag(1)</a>
|
|
for details.</p></div>
|
|
<div class="paragraph"><p>So now we know how Git uses the object database to represent a
|
|
project’s history:</p></div>
|
|
<div class="ulist"><ul>
|
|
<li>
|
|
<p>
|
|
"commit" objects refer to "tree" objects representing the
|
|
snapshot of a directory tree at a particular point in the
|
|
history, and refer to "parent" commits to show how they’re
|
|
connected into the project history.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
"tree" objects represent the state of a single directory,
|
|
associating directory names to "blob" objects containing file
|
|
data and "tree" objects containing subdirectory information.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
"blob" objects contain file data without any other structure.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
References to commit objects at the head of each branch are
|
|
stored in files under .git/refs/heads/.
|
|
</p>
|
|
</li>
|
|
<li>
|
|
<p>
|
|
The name of the current branch is stored in .git/HEAD.
|
|
</p>
|
|
</li>
|
|
</ul></div>
|
|
<div class="paragraph"><p>Note, by the way, that lots of commands take a tree as an argument.
|
|
But as we can see above, a tree can be referred to in many different
|
|
ways—by the SHA-1 name for that tree, by the name of a commit that
|
|
refers to the tree, by the name of a branch whose head refers to that
|
|
tree, etc.--and most such commands can accept any of these names.</p></div>
|
|
<div class="paragraph"><p>In command synopses, the word "tree-ish" is sometimes used to
|
|
designate such an argument.</p></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_the_index_file">The index file</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>The primary tool we’ve been using to create commits is <code>git-commit</code>
|
|
<code>-a</code>, which creates a commit including every change you’ve made to
|
|
your working tree. But what if you want to commit changes only to
|
|
certain files? Or only certain changes to certain files?</p></div>
|
|
<div class="paragraph"><p>If we look at the way commits are created under the cover, we’ll see
|
|
that there are more flexible ways creating commits.</p></div>
|
|
<div class="paragraph"><p>Continuing with our test-project, let’s modify file.txt again:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ echo "hello world, again" >>file.txt</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>but this time instead of immediately making the commit, let’s take an
|
|
intermediate step, and ask for diffs along the way to keep track of
|
|
what’s happening:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git diff
|
|
--- a/file.txt
|
|
+++ b/file.txt
|
|
@@ -1 +1,2 @@
|
|
hello world!
|
|
+hello world, again
|
|
$ git add file.txt
|
|
$ git diff</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>The last diff is empty, but no new commits have been made, and the
|
|
head still doesn’t contain the new line:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git diff HEAD
|
|
diff --git a/file.txt b/file.txt
|
|
index a042389..513feba 100644
|
|
--- a/file.txt
|
|
+++ b/file.txt
|
|
@@ -1 +1,2 @@
|
|
hello world!
|
|
+hello world, again</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>So <em>git diff</em> is comparing against something other than the head.
|
|
The thing that it’s comparing against is actually the index file,
|
|
which is stored in .git/index in a binary format, but whose contents
|
|
we can examine with ls-files:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git ls-files --stage
|
|
100644 513feba2e53ebbd2532419ded848ba19de88ba00 0 file.txt
|
|
$ git cat-file -t 513feba2
|
|
blob
|
|
$ git cat-file blob 513feba2
|
|
hello world!
|
|
hello world, again</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>So what our <em>git add</em> did was store a new blob and then put
|
|
a reference to it in the index file. If we modify the file again,
|
|
we’ll see that the new modifications are reflected in the <em>git diff</em>
|
|
output:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ echo 'again?' >>file.txt
|
|
$ git diff
|
|
index 513feba..ba3da7b 100644
|
|
--- a/file.txt
|
|
+++ b/file.txt
|
|
@@ -1,2 +1,3 @@
|
|
hello world!
|
|
hello world, again
|
|
+again?</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>With the right arguments, <em>git diff</em> can also show us the difference
|
|
between the working directory and the last commit, or between the
|
|
index and the last commit:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git diff HEAD
|
|
diff --git a/file.txt b/file.txt
|
|
index a042389..ba3da7b 100644
|
|
--- a/file.txt
|
|
+++ b/file.txt
|
|
@@ -1 +1,3 @@
|
|
hello world!
|
|
+hello world, again
|
|
+again?
|
|
$ git diff --cached
|
|
diff --git a/file.txt b/file.txt
|
|
index a042389..513feba 100644
|
|
--- a/file.txt
|
|
+++ b/file.txt
|
|
@@ -1 +1,2 @@
|
|
hello world!
|
|
+hello world, again</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>At any time, we can create a new commit using <em>git commit</em> (without
|
|
the "-a" option), and verify that the state committed only includes the
|
|
changes stored in the index file, not the additional change that is
|
|
still only in our working tree:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git commit -m "repeat"
|
|
$ git diff HEAD
|
|
diff --git a/file.txt b/file.txt
|
|
index 513feba..ba3da7b 100644
|
|
--- a/file.txt
|
|
+++ b/file.txt
|
|
@@ -1,2 +1,3 @@
|
|
hello world!
|
|
hello world, again
|
|
+again?</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>So by default <em>git commit</em> uses the index to create the commit, not
|
|
the working tree; the "-a" option to commit tells it to first update
|
|
the index with all changes in the working tree.</p></div>
|
|
<div class="paragraph"><p>Finally, it’s worth looking at the effect of <em>git add</em> on the index
|
|
file:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ echo "goodbye, world" >closing.txt
|
|
$ git add closing.txt</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>The effect of the <em>git add</em> was to add one entry to the index file:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git ls-files --stage
|
|
100644 8b9743b20d4b15be3955fc8d5cd2b09cd2336138 0 closing.txt
|
|
100644 513feba2e53ebbd2532419ded848ba19de88ba00 0 file.txt</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>And, as you can see with cat-file, this new entry refers to the
|
|
current contents of the file:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git cat-file blob 8b9743b2
|
|
goodbye, world</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>The "status" command is a useful way to get a quick summary of the
|
|
situation:</p></div>
|
|
<div class="listingblock">
|
|
<div class="content">
|
|
<pre><code>$ git status
|
|
On branch master
|
|
Changes to be committed:
|
|
(use "git restore --staged <file>..." to unstage)
|
|
|
|
new file: closing.txt
|
|
|
|
Changes not staged for commit:
|
|
(use "git add <file>..." to update what will be committed)
|
|
(use "git restore <file>..." to discard changes in working directory)
|
|
|
|
modified: file.txt</code></pre>
|
|
</div></div>
|
|
<div class="paragraph"><p>Since the current state of closing.txt is cached in the index file,
|
|
it is listed as "Changes to be committed". Since file.txt has
|
|
changes in the working directory that aren’t reflected in the index,
|
|
it is marked "changed but not updated". At this point, running "git
|
|
commit" would create a commit that added closing.txt (with its new
|
|
contents), but that didn’t modify file.txt.</p></div>
|
|
<div class="paragraph"><p>Also, note that a bare <code>git</code> <code>diff</code> shows the changes to file.txt, but
|
|
not the addition of closing.txt, because the version of closing.txt
|
|
in the index file is identical to the one in the working directory.</p></div>
|
|
<div class="paragraph"><p>In addition to being the staging area for new commits, the index file
|
|
is also populated from the object database when checking out a
|
|
branch, and is used to hold the trees involved in a merge operation.
|
|
See <a href="gitcore-tutorial.html">gitcore-tutorial(7)</a> and the relevant man
|
|
pages for details.</p></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_what_next">What next?</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>At this point you should know everything necessary to read the man
|
|
pages for any of the git commands; one good place to start would be
|
|
with the commands mentioned in <a href="giteveryday.html">giteveryday(7)</a>. You
|
|
should be able to find any unknown jargon in <a href="gitglossary.html">gitglossary(7)</a>.</p></div>
|
|
<div class="paragraph"><p>The <a href="user-manual.html">Git User’s Manual</a> provides a more
|
|
comprehensive introduction to Git.</p></div>
|
|
<div class="paragraph"><p><a href="gitcvs-migration.html">gitcvs-migration(7)</a> explains how to
|
|
import a CVS repository into Git, and shows how to use Git in a
|
|
CVS-like way.</p></div>
|
|
<div class="paragraph"><p>For some interesting examples of Git use, see the
|
|
<a href="howto-index.html">howtos</a>.</p></div>
|
|
<div class="paragraph"><p>For Git developers, <a href="gitcore-tutorial.html">gitcore-tutorial(7)</a> goes
|
|
into detail on the lower-level Git mechanisms involved in, for
|
|
example, creating a new commit.</p></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_see_also">SEE ALSO</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p><a href="gittutorial.html">gittutorial(7)</a>,
|
|
<a href="gitcvs-migration.html">gitcvs-migration(7)</a>,
|
|
<a href="gitcore-tutorial.html">gitcore-tutorial(7)</a>,
|
|
<a href="gitglossary.html">gitglossary(7)</a>,
|
|
<a href="git-help.html">git-help(1)</a>,
|
|
<a href="giteveryday.html">giteveryday(7)</a>,
|
|
<a href="user-manual.html">The Git User’s Manual</a></p></div>
|
|
</div>
|
|
</div>
|
|
<div class="sect1">
|
|
<h2 id="_git">GIT</h2>
|
|
<div class="sectionbody">
|
|
<div class="paragraph"><p>Part of the <a href="git.html">git(1)</a> suite</p></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
<div id="footnotes"><hr /></div>
|
|
<div id="footer">
|
|
<div id="footer-text">
|
|
Last updated
|
|
2025-08-18 02:18:23 CEST
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</body>
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