6 Linux metacharacters I love using on the command line

Early in my Linux journey, I learned how to use the command line. This is what makes Linux unique. I might lose the graphical user interface (GUI), but there's no need to completely rebuild the machine. Many Linux computers run in headless mode, allowing you to complete all administrative tasks on the command line. It uses many basic commands that everyone is familiar with, such as ls, ls-l, ls-l, cd, pwd, top, etc.

Shell metacharacters on Linux

You can expand each of these commands by using metacharacters. I don't know what you call them, but using metacharacters on the Linux command line is a great way to increase productivity.

Pipeline |

Suppose I want to know all instances of Firefox running on my system. I can use the ps command with -ef to list all instances of a program running on my system. Now I want to look at those instances involving Firefox. I use one of my favorite metacharacters, piping | to the grep program, which scans the entire file contents. means

ps

and grep commands are executed at the same time<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class='brush:php;toolbar:false;'>linuxmi@linuxmi /home/linuxmi/www.linuxmi.com                               ⚡ ps -ef | grep firefox </pre><div class="contentsignin">Copy after login</div></div> <h2 style="margin-top: 30px;margin-bottom: 15px;padding: 0px;font-weight: bold;color: black;font-size: 22px;text-align: left;margin: 20px 10px 0px 0px"><span class="content" style="font-size: 18px;font-weight: bold;color: #222;display: inline-block;padding-left: 10px;border-left: 5px solid #f83929"><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/887/227/170779863019344.png" class="lazy" alt="我喜欢在命令行中使用的 6 个 Linux 元字符" /></span></h2> <h2 id="span-class-content-style-font-size-px-font-weight-bold-color-display-inline-block-padding-left-px-border-left-px-solid-f-Output-Redirection-span"><span class="content" style="font-size: 18px;font-weight: bold;color: #222;display: inline-block;padding-left: 10px;border-left: 5px solid #f83929">Output Redirection ></span></h2> <p>Another favorite metacharacter is output redirection <code style="font-size: 14px;padding: 2px 4px;border-radius: 4px;margin: 0 2px;font-family: Operator Mono, Consolas, Monaco, Menlo, monospace;color: #10f5d6c">>. I use it to display dmesg messages for the eth0 user interface using the grep option followed by eth0. The command results are saved to linuxmi.txt. You may find this useful.

linuxmi@linuxmi /home/linuxmi/www.linuxmi.com                              
⚡ sudo dmesg | grep -i eth0 > linuxmi.txt
[sudo] linuxmi 的密码： 

linuxmi@linuxmi /home/linuxmi/www.linuxmi.com                              
⚡ cat linuxmi.txt
[    3.647685] e1000 0000:02:01.0 eth0: (PCI:66MHz:32-bit) 00:0c:29:0e:a2:7c
[    3.647694] e1000 0000:02:01.0 eth0: Intel(R) PRO/1000 Network Connection
[    3.651280] e1000 0000:02:01.0 ens33: renamed from eth0

Asterisk *

The asterisk * or wildcard characters are preferred when looking for files with the same extension (such as .jpg or .png). I first enter the image directory in the system, and then use the following command:

linuxmi@linuxmi /home/linuxmi/www.linuxmi.com                              
⚡ ls *.png
linuxmi.com.png  www.linuxmi.com.png

tilde~

The tilde ~ is a quick way to return to the home directory of your Linux system by entering the following command:

linuxmi@linuxmi /home/linuxmi/www.linuxmi.com                              
⚡ cd ~

linuxmi@linuxmi /home/linuxmi                                              
⚡ pwd                  
/home/linuxmi

Dollar sign $

The $ symbol as a metacharacter has a different meaning. When used to match a pattern, it represents any string that ends with the given string. For example, when using the metacharacters | and $ together:

linuxmi@linuxmi /home/linuxmi/www.linuxmi.com                              
⚡ ls | grep png$

插入符号^

^ 符号将结果限制为以给定字符串开头的项。例如，当同时使用元字符 |和^时：

linuxmi@linuxmi /home/linuxmi/www.linuxmi.com                              
⚡ ls | grep ^linuxmi

其中许多元字符是通向正则表达式的入口，因此还有很多东西需要探索。请问下你最熟悉的 Linux 元字符是什么，它们是如何拯救你的工作的？

相关文章：

• 在 Linux 系统上使用更好的正则表达式 https://www.linuxmi.com/linux-regular-expression-grep.html
• 5种使用正则表达式搜索纯文本数据的最佳命令行工具 https://www.linuxmi.com/5-regex-minglinghang.html

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