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diff --git a/posts/3/index.html b/posts/3/index.html new file mode 100644 index 0000000..7608da9 --- /dev/null +++ b/posts/3/index.html @@ -0,0 +1,282 @@ +<!DOCTYPE html> +<html lang="en"> +<head> + <meta charset="utf-8" /> + <meta name="generator" content="Hugo 0.108.0"> + + <meta http-equiv="X-UA-Compatible" content="IE=edge" /> + <meta name="viewport" content="width=device-width, initial-scale=1" /> + <meta name="author" content="garhve" /> + <meta property="og:url" content="https://blog.garhve.com/posts/3/" /> + <link rel="canonical" href="https://blog.garhve.com/posts/3/" /><link rel="apple-touch-icon" href="https://assets.garhve.com/pictures/assets/images/favicon/favicon.ico" /> + <link rel="icon" href="https://assets.garhve.com/pictures/assets/images/favicon/favicon.ico" /> + <link rel="shortcut" href="https://assets.garhve.com/pictures/assets/images/favicon/favicon.ico" /><link rel="alternate" type="application/atom+xml" href="https://blog.garhve.comindex.xml" title="blog | garhve's hub"> + + <script type="application/ld+json"> + { + "@context" : "http://schema.org", + "@type" : "BlogPosting", + "mainEntityOfPage": { + "@type": "WebPage", + "@id": "https:\/\/blog.garhve.com" + }, + "articleSection" : "posts", + "name" : "Mess with bash(1)", + "headline" : "Mess with bash(1)", + "description" : "Crontab crontab is a useful tool, I really regret that I don\u0026rsquo;t familar it earlier.\nIt\u0026rsquo;s usage really simple, and these two are my frequent using:\ncrontab -e #edit crontab file that reside in \/var\/spool\/cron crontab -l #list current crontab job It basic syntax as follow, also really simple example of usage:\ndelete file foo every minute * * * * * rm foo delete file foo every 15 minutes 15 * * * * rm foo delete file foo every beginning of hour 0 * * * * rm foo delete file foo every minute after 3 hours * 3 * * * rm foo delete file foo every day at 18:30 30 18 * * * rm foo delete file foo every beginning of month 0 0 0 * * rm foo delete file foo on beginning of 1st,10th of month 0 0 1,10 * * rm foo The usage really simple, I now use it to renew my SSL certification and daily update bt-tracker.", + "inLanguage" : "en-US", + "author" : "garhve", + "creator" : "garhve", + "publisher": "garhve", + "accountablePerson" : "garhve", + "copyrightHolder" : "garhve", + "copyrightYear" : "2022", + "datePublished": "2022-08-25 13:40:56 \u002b0800 CST", + "dateModified" : "2022-08-25 13:40:56 \u002b0800 CST", + "url" : "https:\/\/blog.garhve.com\/posts\/3\/", + "keywords" : [ ] + } +</script> +<title>Mess with bash(1)</title> + <meta property="og:title" content="Mess with bash(1)" /> + <meta property="og:type" content="article" /> + <meta property="og:description" content="Crontab crontab is a useful tool, I really regret that I don&rsquo;t familar it earlier. +It&rsquo;s usage really simple, and these two are my frequent using: +crontab -e #edit crontab file that reside in /var/spool/cron crontab -l #list current crontab job It basic syntax as follow, also really simple example of usage: +delete file foo every minute * * * * * rm foo delete file foo every 15 minutes 15 * * * * rm foo delete file foo every beginning of hour 0 * * * * rm foo delete file foo every minute after 3 hours * 3 * * * rm foo delete file foo every day at 18:30 30 18 * * * rm foo delete file foo every beginning of month 0 0 0 * * rm foo delete file foo on beginning of 1st,10th of month 0 0 1,10 * * rm foo The usage really simple, I now use it to renew my SSL certification and daily update bt-tracker." /> + <meta name="description" content="Crontab crontab is a useful tool, I really regret that I don&rsquo;t familar it earlier. +It&rsquo;s usage really simple, and these two are my frequent using: +crontab -e #edit crontab file that reside in /var/spool/cron crontab -l #list current crontab job It basic syntax as follow, also really simple example of usage: +delete file foo every minute * * * * * rm foo delete file foo every 15 minutes 15 * * * * rm foo delete file foo every beginning of hour 0 * * * * rm foo delete file foo every minute after 3 hours * 3 * * * rm foo delete file foo every day at 18:30 30 18 * * * rm foo delete file foo every beginning of month 0 0 0 * * rm foo delete file foo on beginning of 1st,10th of month 0 0 1,10 * * rm foo The usage really simple, I now use it to renew my SSL certification and daily update bt-tracker." /> + <meta property="og:locale" content="en-us" /><meta property="og:image" content="https://assets.garhve.com/pictures/assets/images/favicon/favicon.ico" /> + + + + + <style>@font-face{font-family:huanzi;src:url(/fonts/huanzi.woff2)format('woff2')}@font-face{font-family:fira code;src:url(/fonts/FiraCode-Regular.woff2)format('woff2')}body{font-family:bree serif,huanzi,sans-serif;-webkit-font-smoothing:antialiased;margin:0 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+ + + + + <link href="/index.xml" rel="alternate" type="application/rss+xml" + title="blog | garhve's hub"> + + <link rel="preconnect" href="https://fonts.gstatic.com"> + <link href="https://fonts.googleapis.com/css?family=Bree+Serif|Bungee+Shade" rel="stylesheet"> + + + +</head> + + +<body> + <article class="post English" id="article"> + <div class="row"> + <div class="col-xs-12"> + <div class="site-header"> + +<header> + <div class="header-title"> + <a href="/" + >Garhve</a + > + </div> + <div class="header-subtitle"></div> +</header> +<div class="row end-md center-xs header-items"> +</div> +<div class="row end-xs"> + + <div class="lang-switch col-xs-3 col-xs-offset-9"> + <a href="/cn/">Chinese</a> + </div> + +</div> +<div class="header-line"></div> + + </div> + <header class="post-header"> + <h1 class="post-title">Mess with bash(1)</h1> + + <div class="row post-desc"> + <div class="col-xs-6"> + + <time class="post-date" datetime="2022-08-25 13:40:56 CST"> + 25 Aug 2022 + </time> + + </div> + <div class="col-xs-6"> + + <div class="post-author"> + <a target="_blank" href="https://garhve.com">@garhve</a> + </div> + + </div> + </div> + + </header> + + <div class="post-content markdown-body"> + + <h3 id="crontab">Crontab</h3> +<p><code>crontab</code> is a useful tool, I really regret that I don’t familar it earlier.</p> +<p>It’s usage really simple, and these two are my frequent using:</p> +<div class="highlight"><pre tabindex="0" style="background-color:#fff;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>crontab -e <span style="font-style:italic">#edit crontab file that reside in /var/spool/cron</span> +</span></span><span style="display:flex;"><span>crontab -l <span style="font-style:italic">#list current crontab job</span> +</span></span></code></pre></div><p>It basic syntax as follow, also really simple +<img src="https://assets.garhve.com/pictures/screenshots/2022/08/1857817000.jpg" alt="crontab-layout.jpg"></p> +<p>example of usage:</p> +<ol> +<li>delete file <em>foo</em> every minute +<code>* * * * * rm foo</code></li> +<li>delete file <em>foo</em> every 15 minutes +<code>15 * * * * rm foo</code></li> +<li>delete file <em>foo</em> every beginning of hour +<code>0 * * * * rm foo</code></li> +<li>delete file <em>foo</em> every minute after 3 hours +<code>* 3 * * * rm foo</code></li> +<li>delete file <em>foo</em> every day at 18:30 +<code>30 18 * * * rm foo</code></li> +<li>delete file <em>foo</em> every beginning of month +<code>0 0 0 * * rm foo</code></li> +<li>delete file <em>foo</em> on beginning of 1st,10th of month +<code>0 0 1,10 * * rm foo</code></li> +</ol> +<p>The usage really simple, I now use it to renew my SSL certification and daily update bt-tracker.</p> +<hr> +<h3 id="tr">tr</h3> +<p><code>tr</code> is really useful when encountered situation that needs struggle with string. +Three frequency ways of using <code>tr</code></p> +<ol> +<li> +<p><strong>shrink</strong> multiple characters into single one</p> +<p><code>tr -s '[string]'</code> +e.g. <code>echo "ssssssspaaaaace" | tr -s 'sa'</code> would convert “ssssssspace” to “space”</p> +</li> +<li> +<p><strong>delete</strong> specific character. I usually use it to delete white space or delimiter</p> +<p><code>tr -d '[string]'</code> +e.g. <code>echo "blog.garhve.com" | tr -d '.o'</code> would convert url to “blggarhvecm”</p> +</li> +<li> +<p><strong>convert</strong> specific character to another one.</p> +<p><code>tr '[string1]' '[string2]'</code> +e.g. <code>echo "woopwon | tr "wo" "fe"</code> would result “feepfen”</p> +</li> +</ol> +<hr> +<h3 id="cut">cut</h3> +<p>I use <code>cut</code> mostly to get word from a string, especially get relative path from absolute path. Because I always want to loop to get same sub-directories file from different main directory, <code>cut</code> helps a lot.</p> +<p>for now, I only use it one way</p> +<p><code>echo string | cut -d '[character]' -f position</code> +e.g. <code>echo path/to/most/inner/file | cut -d '/' -f1</code> this will give me word before first ‘/’, which is ‘path’</p> +<p>Often, <code>rev</code> will co-work with <code>cut</code> to get last one word</p> +<p>e.g. <code>echo blog.garhve.com | rev | cut -d '.' -f 1 | rev</code> this will give word after last ‘/’, which is com.</p> +<blockquote> +<p><em>a worth noting here is that the <code>rev</code> command needs to appear twice because it usage is not so intuitive, it reverse whole string</em></p> +<p><code>echo "hello world" | rev</code> will get ‘dlrow olleh`</p> +<p><code>echo "hello world" | cut -d ' ' -f1 | rev</code> will give result of ‘dlrow’</p> +<p><code>echo "hello world" | rev | cut -d ' ' -f1</code> will give same result, as ‘dlrow’</p> +<p><code>echo "hello world" | rev | cut -d ' ' -f1 | rev</code> will give expected result, as ‘world’</p> +</blockquote> +<h3 id="daily-update-bt-tracker">Daily update bt tracker</h3> +<p>I already learn shell script for a while.. so I wrote a simple script to test whether I really got used to it, but result is obviously, I need more and more practice to memorize commands.</p> +<div class="highlight"><pre tabindex="0" style="background-color:#fff;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span><span style="">#! /bin/sh +</span></span></span><span style="display:flex;"><span><span style=""></span><span style="font-style:italic">#bt-tracker.txt</span> +</span></span><span style="display:flex;"><span>site=https://raw.githubusercontent.com/ngosang/trackerslist/master/trackers_all.txt +</span></span><span style="display:flex;"><span> +</span></span><span style="display:flex;"><span>file=/path_to_aria_directory/aria2.conf +</span></span><span style="display:flex;"><span> +</span></span><span style="display:flex;"><span>Addr=user@addr +</span></span><span style="display:flex;"><span> +</span></span><span style="display:flex;"><span><span style="font-style:italic"># Get bt-tracker and format it to fulfill aria needs, then store in variable</span> +</span></span><span style="display:flex;"><span>bt=<span style="font-weight:bold">$(</span>curl $site | tr -s <span style="font-style:italic">'[:space:]'</span> | tr <span style="font-style:italic">'[:space:]'</span> <span style="font-style:italic">','</span><span style="font-weight:bold">)</span> +</span></span><span style="display:flex;"><span> +</span></span><span style="display:flex;"><span><span style="font-style:italic"># sshpass is a software, that can allow me pass ssh password as argument</span> +</span></span><span style="display:flex;"><span><span style="font-style:italic"># so that I don't need to wait prompt</span> +</span></span><span style="display:flex;"><span><span style="font-style:italic"># 410 is the line of bt tracker resides, I now no other way to replace it.</span> +</span></span><span style="display:flex;"><span><span style="font-weight:bold">$(</span>sshpass -p <span style="font-style:italic">'password'</span> ssh -T $Addr <span style="font-style:italic">"sed -i '410d' </span>$file<span style="font-style:italic"> | echo </span>$bt<span style="font-style:italic"> >> </span>$file<span style="font-style:italic">"</span><span style="font-weight:bold">)</span> +</span></span></code></pre></div><blockquote> +<p>Usage of <a href="https://blog.garhve.com/index.php/archives/23/#tr">tr</a> and <a href="https://blog.garhve.com/index.php/archives/23/#cut">cut</a>, expansion of ‘command tips’ is needed</p> +</blockquote> +<h3 id="ways-to-find-files-or-specific-string-in-files">Ways to find files or specific string in files</h3> +<p>In order to look up C definitions, I need to know where linux stores header files or which files store definitions I need. So that here comes up some methods to fulfill this need:</p> +<ol> +<li><code>find 'path' -name 'file_name'</code></li> +</ol> +<blockquote> +<p>e.g. <code>find / -name stdio.h</code> will return multiple location that stdio.h resides. this could expand to look for others</p> +<p><img src="https://assets.garhve.com/pictures/screenshots/2022/09/find_name.png" alt="image.png"></p> +<p>more info could see <code>man find</code></p> +</blockquote> +<hr> +<ol start="2"> +<li><code>grep -rnw 'path' -e 'pattern'</code></li> +</ol> +<blockquote> +<p>e.g. `grep –include=*.{h,c} -rnw / -e “from_kuid” will return string and filename that contains string.</p> +<p><img src="https://assets.garhve.com/pictures/screenshots/2022/09/grep_string.png" alt="image.png"></p> +<ul> +<li><code>-r</code> or <code>-R</code> is recursive,</li> +<li><code>-n</code> is line number, and</li> +<li><code>-w</code> stands for match the whole word.</li> +<li><code>-l</code> (lower-case L) can be added to just give the file name of matching files.</li> +<li><code>-e</code> is the pattern used during the search</li> +</ul> +<p>Along with these, <code>--exclude</code>, <code>--include</code>, <code>--exclude-dir</code> flags could be used for efficient searching:</p> +<ul> +<li>This will only search through those files which have .c or .h extensions:</li> +</ul> +<div class="highlight"><pre tabindex="0" style="background-color:#fff;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>grep --include=<span style="font-weight:bold;font-style:italic">\*</span>.{c,h} -rnw <span style="font-style:italic">'/path/to/somewhere/'</span> -e <span style="font-style:italic">"pattern"</span> +</span></span></code></pre></div><ul> +<li>This will exclude searching all the files ending with .o extension:</li> +</ul> +<div class="highlight"><pre tabindex="0" style="background-color:#fff;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>grep --exclude=<span style="font-weight:bold;font-style:italic">\*</span>.o -rnw <span style="font-style:italic">'/path/to/somewhere/'</span> -e <span style="font-style:italic">"pattern"</span> +</span></span></code></pre></div><ul> +<li>For directories it’s possible to exclude one or more directories using the <code>--exclude-dir</code> parameter. For example, this will exclude the dirs dir1/, dir2/ and all of them matching *.dst/:</li> +</ul> +<div class="highlight"><pre tabindex="0" style="background-color:#fff;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-bash" data-lang="bash"><span style="display:flex;"><span>grep --exclude-dir={dir1,dir2,*.dst} -rnw <span style="font-style:italic">'/path/to/somewhere/'</span> -e <span style="font-style:italic">"pattern"</span> +</span></span></code></pre></div><p>more info could see <a href="https://ss64.com/bash/grep.html"><code>man grep</code></a>.</p> +</blockquote> + + </div> + + <div class="row"> + <div class="col-xs-12"> + + </div> + </div> + + + <div style="height: 50px;"></div> + + + <div class="site-footer"> + + + +</div> + + </div> + </div> + </article> + + + +<script> + + + + + +</script> + + + +</body> + +</html> |