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diff --git a/public/post/mess-with-bash-1/index.html b/public/post/mess-with-bash-1/index.html new file mode 100644 index 0000000..3de81d7 --- /dev/null +++ b/public/post/mess-with-bash-1/index.html @@ -0,0 +1,194 @@ +<!DOCTYPE html> +<html lang="en"> + +<head> + <meta charset="utf-8"> + +<title>Mess with bash(1) | garhve's gibberish</title> + + + <link rel="shortcut icon" type="image/png" href="/images/favicon.png"> + <meta name="viewport" content="width=device-width,initial-scale=1"> + + <link id="stylesheet" rel="stylesheet" type="text/css" href="/dark.css"> + + <script type="text/javascript" src="/js/theme.js"></script> + +</head> + +<div class="header"> + <div class="site_title"> + <p><a href="/"><img src="https://blog.garhve.com/images/logo.ico" alt="garhve's gibberish" + width="70" height=auto></a></p> + <p><a href="/"> garhve's gibberish</a></p> + </div> + <div class="menu"> + <!-- <a href="/tags">tags</a> + --><a href="/categories">categories</a> + </div> +</div> + +<body onload="getTheme()"> + <section class="section"> + <div class="container"> + +<p> + <div class="title_postpage">Mess with bash(1)</div> +</p> +<p> + <div class="date_postpage">2022-08-25</div> + <div class="taxonomies_postpage"> + + + <a href="https://blog.garhve.com/categories/code/">/code</a> + + + + +  <a href="https://blog.garhve.com/tags/bash/">#bash</a> + + + </div> +</p> + +<p> + <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> +<pre data-lang="bash" style="background-color:#2e3440;color:#d8dee9;" class="language-bash "><code class="language-bash" data-lang="bash"><span style="color:#88c0d0;">crontab</span><span> -e </span><span style="color:#616e88;">#edit crontab file that reside in /var/spool/cron +</span><span style="color:#88c0d0;">crontab</span><span> -l </span><span style="color:#616e88;">#list current crontab job +</span></code></pre> +<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> +<pre data-lang="bash" style="background-color:#2e3440;color:#d8dee9;" class="language-bash "><code class="language-bash" data-lang="bash"><span style="color:#616e88;">#! /bin/sh +</span><span style="color:#616e88;">#bt-tracker.txt +</span><span>site</span><span style="color:#81a1c1;">=</span><span style="color:#a3be8c;">https://raw.githubusercontent.com/ngosang/trackerslist/master/trackers_all.txt +</span><span> +</span><span>file</span><span style="color:#81a1c1;">=</span><span style="color:#a3be8c;">/path_to_aria_directory/aria2.conf +</span><span> +</span><span>Addr</span><span style="color:#81a1c1;">=</span><span style="color:#a3be8c;">user@addr +</span><span> +</span><span style="color:#616e88;"># Get bt-tracker and format it to fulfill aria needs, then store in variable +</span><span>bt</span><span style="color:#81a1c1;">=$</span><span style="color:#a3be8c;">(</span><span style="color:#88c0d0;">curl </span><span style="color:#81a1c1;">$</span><span>site </span><span style="color:#81a1c1;">| </span><span style="color:#88c0d0;">tr</span><span> -s </span><span style="color:#a3be8c;">'[:space:]' </span><span style="color:#81a1c1;">| </span><span style="color:#88c0d0;">tr </span><span style="color:#a3be8c;">'[:space:]' ',') +</span><span> +</span><span style="color:#616e88;"># sshpass is a software, that can allow me pass ssh password as argument +</span><span style="color:#616e88;"># so that I don't need to wait prompt +</span><span style="color:#616e88;"># 410 is the line of bt tracker resides, I now no other way to replace it. +</span><span style="color:#81a1c1;">$</span><span style="color:#88c0d0;">(sshpass</span><span> -p </span><span style="color:#a3be8c;">'password'</span><span style="color:#88c0d0;"> ssh</span><span> -T </span><span style="color:#81a1c1;">$</span><span>Addr </span><span style="color:#a3be8c;">"sed -i '410d' </span><span style="color:#81a1c1;">$</span><span>file</span><span style="color:#a3be8c;"> | echo </span><span style="color:#81a1c1;">$</span><span>bt</span><span style="color:#a3be8c;"> >> </span><span style="color:#81a1c1;">$</span><span>file</span><span style="color:#a3be8c;">"</span><span style="color:#88c0d0;">) +</span></code></pre> +<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> +<pre data-lang="bash" style="background-color:#2e3440;color:#d8dee9;" class="language-bash "><code class="language-bash" data-lang="bash"><span style="color:#88c0d0;">grep</span><span> --include</span><span style="color:#81a1c1;">=</span><span style="color:#ebcb8b;">\*</span><span>.{c</span><span style="color:#eceff4;">,</span><span>h} -rnw </span><span style="color:#a3be8c;">'/path/to/somewhere/'</span><span> -e </span><span style="color:#a3be8c;">"pattern" +</span></code></pre> +<ul> +<li>This will exclude searching all the files ending with .o extension:</li> +</ul> +<pre data-lang="bash" style="background-color:#2e3440;color:#d8dee9;" class="language-bash "><code class="language-bash" data-lang="bash"><span style="color:#88c0d0;">grep</span><span> --exclude</span><span style="color:#81a1c1;">=</span><span style="color:#ebcb8b;">\*</span><span>.o -rnw </span><span style="color:#a3be8c;">'/path/to/somewhere/'</span><span> -e </span><span style="color:#a3be8c;">"pattern" +</span></code></pre> +<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> +<pre data-lang="bash" style="background-color:#2e3440;color:#d8dee9;" class="language-bash "><code class="language-bash" data-lang="bash"><span style="color:#88c0d0;">grep</span><span> --exclude-dir</span><span style="color:#81a1c1;">=</span><span>{dir1</span><span style="color:#eceff4;">,</span><span>dir2</span><span style="color:#eceff4;">,</span><span style="color:#81a1c1;">*</span><span>.dst} -rnw </span><span style="color:#a3be8c;">'/path/to/somewhere/'</span><span> -e </span><span style="color:#a3be8c;">"pattern" +</span></code></pre> +<p>more info could see <a href="https://ss64.com/bash/grep.html">man grep</a>.</p> +</blockquote> + +</p> + + + + + </div> + </section> +</body> + +<div class="footer"> +  © garhve +</div> + +</html> |