https://docs.pelican.bernatchez.net/lang-version.en/2025-05-24T18:23:52+00:002025-05-24T18:23:52+00:002025-05-24T18:23:52+00:00Pierre Bernatcheztag:docs.pelican.bernatchez.net,2025-05-24:/lang-version.en/patchhowto-en.html

<p class="first last">how to create file patches</p>

<div class="section" id="single-file"> <h2>Single File</h2> <p>This is how to build a patch file that you then apply on a target system to modify one of its files.</p> <p><strong>Get original copy</strong></p> <div class="highlight"><pre><span></span>cp<span class="w"> </span>/pathtofile/myfile.conf<span class="w"> </span>/pathtofile/myfile.conf.orig </pre></div> <p><strong>Edit the file manually</strong></p> <p>Using any editor, manually make changes to the file /pathtofile/myfile.conf as desired.</p> <p><strong>Capture the difference in a patch</strong></p> <div class="highlight"><pre><span></span>diff<span class="w"> </span>-u<span class="w"> </span>/pathtofile/myfile.conf.orig<span class="w"> </span>/pathtofile/myfile.conf<span class="w"> </span>&gt;myfile.patch </pre></div> <p><strong>Try the patch</strong></p> <p>Undo the manual changes you made</p> <div class="highlight"><pre><span></span>patch<span class="w"> </span>-R<span class="w"> </span>-p0<span class="w"> </span>&lt;myfile.patch </pre></div> <p>Redo your changes</p> <div class="highlight"><pre><span></span>patch<span class="w"> </span>-p0<span class="w"> </span>&lt;myfile.patch </pre></div> </div> <div class="section" id="recursive-directory"> <h2>Recursive Directory</h2> <p>In this example capture all the changes we make to a tree of pelican-themes into a single patch file.</p> <p><strong>Duplicate</strong></p> <p>We start by duplicating the complete tree.</p> <div class="highlight"><pre><span></span>cp<span class="w"> </span>-r<span class="w"> </span><span class="si">${</span><span class="nv">HOME</span><span class="si">}</span>/pelican-themes<span class="w"> </span><span class="si">${</span><span class="nv">HOME</span><span class="si">}</span>/pelican-themes.orig </pre></div> <p><strong>TIP</strong></p> <p>I have a tendency keep my orig copy and reuse it a lot as I modify things. To guard against inadvertantly changing something within the orig version without noticing and thereby undermining all subsequent diffs may make, I like to boiler plate the .orig files a bit by write protecting them. This is not necessary but it has served me well.</p> <div class="highlight"><pre><span></span>chmod<span class="w"> </span>-w<span class="w"> </span>--recursive<span class="w"> </span>pelican-themes.orig/ </pre></div> <p><strong>Create Patch File</strong></p> <p>Now we make all the changes we want within the pelican-themes directory. Once that is done we create the patch file incorporationg all changes.</p> <div class="highlight"><pre><span></span><span class="nb">cd</span><span class="w"> </span><span class="si">${</span><span class="nv">HOME</span><span class="si">}</span>/pelican-themes diff<span class="w"> </span>-Naru<span class="w"> </span>../pelican-themes.orig<span class="w"> </span>.<span class="w"> </span>&gt;<span class="w"> </span>../pelican-themes.patch </pre></div> <p>Note:</p> <blockquote> <div class="line-block"> <div class="line">-N --new-file treat absent files as empty</div> <div class="line">-a --text treat all files as text</div> <div class="line">-r --recursive recursively compare subdirectories</div> <div class="line">-u -U --unified[=NUM] Output NUM lines of unified context (default 3)</div> </div> </blockquote> <p><strong>Undo Changes</strong></p> <div class="highlight"><pre><span></span><span class="nb">cd</span><span class="w"> </span><span class="si">${</span><span class="nv">HOME</span><span class="si">}</span>/pelican-themes patch<span class="w"> </span>-Rs<span class="w"> </span>-p0<span class="w"> </span>&lt;<span class="w"> </span><span class="si">${</span><span class="nv">HOME</span><span class="si">}</span>/pelican-themes.patch </pre></div> <p>Note:</p> <blockquote> <div class="line-block"> <div class="line">Remember that directories created by patch must be removed manually</div> <div class="line">-R --reverse Assume the patch was created with old and new files swapped</div> <div class="line">-s --silent be quiet unless error occurs</div> <div class="line">-pN Strip smallest filepath prefix containing N slashes. 0 means full path.</div> </div> </blockquote> <p><strong>Apply Patch Changes</strong></p> <div class="highlight"><pre><span></span><span class="nb">cd</span><span class="w"> </span><span class="si">${</span><span class="nv">HOME</span><span class="si">}</span>/pelican-themes patch<span class="w"> </span>-s<span class="w"> </span>-p0<span class="w"> </span>&lt;<span class="w"> </span><span class="si">${</span><span class="nv">HOME</span><span class="si">}</span>/pelican-themes.patch </pre></div> </div>