


In Linux, you can use the sed command to delete certain lines of the specified file. Execute the "sed 'M,Nd' file name" statement to delete the contents of consecutive lines from M to N. Execute "sed ' N1d;N2d;N3d;$d' file name" statement can delete the contents of discontinuous lines N1, N2, and N3. Execute the "sed '/specific character/d' file name" statement to delete lines containing specific characters. Execute The "sed '/^Specific character/d' file name" statement can delete lines starting with specific characters.
#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.
In Linux, you can use the sed command to delete certain lines of a specified file.
sed is the abbreviation of Stream Editor. It is used for basic text conversion in Linux. It is an important command for file operations. Therefore, we can also use it to achieve text deletion operations.
The following are some usage examples of sed commands, covering most usage scenarios. They help you learn the sed command from shallow to deep, allowing you to easily and efficiently delete specific lines of files.
First we prepare a demonstration file sed-demo.txt and take a look at the file content
cat sed-demo.txt
Then we can use the sed command to experiment.
1. Delete a certain line
First, we start by deleting a certain line, such as deleting the first line and the last line. In fact, It's the Nth row.
The command format to delete the Nth line:
sed 'Nd' file
Let’s try to delete the first line:
sed '1d' sed-demo.txt
Very Simple, right? There won’t be much explanation here. If you want to delete the content of which line, you only need to replace 1 in the command and it will be ok.
Then the question comes, what number is used to represent the last line? Here is a little tip for you, you can use the dollar sign $ to represent the end, so the command to delete the last line can be written like this:
sed '$d' sed-demo.txt
2. Delete Certain lines
#sed command can delete consecutive or non-consecutive lines.
Delete consecutive rows, for example, delete the content from rows 5 to 7:
sed '5,7d' sed-demo.txt
sed '1d;5d;9d;$d' sed-demo.txt
sed '3,6!d' sed-demo.txt
3. Delete blank lines
sed also supports deleting blank lines in files, the command is as follows:
sed '/^$/d' sed-demo.txt
4. Delete lines containing specific characters
Suppose we want to delete lines containing the word System in the sample file, we You can use /System/, which means that the string System will be matched if it appears. The specific command is as follows:sed '/System/d' sed-demo.txt
sed '/System\|Linux/d' sed-demo.txt
\| represents logical OR. The above command means that all lines with System or Linux in the text are To delete.
5. Delete lines starting with specific characters
First, we create another sample file sed-demo-1.txt for better Demonstration, the content is as follows:cat sed-demo-1.txt
sed '/^R/d' sed-demo-1.txt
那么问题来了,比如我想删除以 R 或者 F 开头的行,那我是不是要执行两次命令呢?如果是有更多岂不是要执行多次命令?这里它有一个简单的写法,你只要把这些字符写在一对中括号 [] 里就可以了:
sed '/^[RF]/d' sed-demo-1.txt
上面命令的作用是 删除以 R 或者 F 开头的行。
6. 删除特定字符结尾的行
同上面一个道理,删除以某一个字符结尾的行,比方说删除以 m 结尾的行,我们可以这样做:
sed '/m$/d' sed-demo.txt
删除以 x 或 m 结尾的行可以这样写:
sed '/[xm]$/d' sed-demo.txt
7. 删除以大写字母开头的行
这里问题又来了,我想要删除所有以大写字母开头的行呢?按照上面的做法是不是要将 A 到 Z 这 26 个字母都写进 [ ] 里呢?其实我们大可不必这样做,在 A 和 Z 中间加个 - 就可以了:
sed '/^[A-Z]/d' sed-demo-1.txt
机智的你看到这里肯定会想到其他类似的用法的了,不妨看看下面是否有你想到的命令吧。
8. 删除包含字母字符的行
sed '/[A-Za-z]/d' sed-demo-1.txt
9. 删除包含数字的行
sed '/[0-9]/d' sed-demo-1.txt
另外,通过这个例子,我们可以加上 ^ 和 $ 更好地看到他们之间的区别:
sed '/^[0-9]/d' sed-demo-1.txt
sed '/[0-9]$/d' sed-demo-1.txt
相关推荐:《Linux视频教程》
The above is the detailed content of How to delete certain lines of a file in Linux. For more information, please follow other related articles on the PHP Chinese website!

linux设备节点是应用程序和设备驱动程序沟通的一个桥梁;设备节点被创建在“/dev”,是连接内核与用户层的枢纽,相当于硬盘的inode一样的东西,记录了硬件设备的位置和信息。设备节点使用户可以与内核进行硬件的沟通,读写设备以及其他的操作。

区别:1、open是UNIX系统调用函数,而fopen是ANSIC标准中的C语言库函数;2、open的移植性没fopen好;3、fopen只能操纵普通正规文件,而open可以操作普通文件、网络套接字等;4、open无缓冲,fopen有缓冲。

端口映射又称端口转发,是指将外部主机的IP地址的端口映射到Intranet中的一台计算机,当用户访问外网IP的这个端口时,服务器自动将请求映射到对应局域网内部的机器上;可以通过使用动态或固定的公共网络IP路由ADSL宽带路由器来实现。

在linux中,交叉编译是指在一个平台上生成另一个平台上的可执行代码,即编译源代码的平台和执行源代码编译后程序的平台是两个不同的平台。使用交叉编译的原因:1、目标系统没有能力在其上进行本地编译;2、有能力进行源代码编译的平台与目标平台不同。

在linux中,eof是自定义终止符,是“END Of File”的缩写;因为是自定义的终止符,所以eof就不是固定的,可以随意的设置别名,linux中按“ctrl+d”就代表eof,eof一般会配合cat命令用于多行文本输出,指文件末尾。

在linux中,可以利用“rpm -qa pcre”命令判断pcre是否安装;rpm命令专门用于管理各项套件,使用该命令后,若结果中出现pcre的版本信息,则表示pcre已经安装,若没有出现版本信息,则表示没有安装pcre。

linux查询mac地址的方法:1、打开系统,在桌面中点击鼠标右键,选择“打开终端”;2、在终端中,执行“ifconfig”命令,查看输出结果,在输出信息第四行中紧跟“ether”单词后的字符串就是mac地址。

在linux中,rpc是远程过程调用的意思,是Reomote Procedure Call的缩写,特指一种隐藏了过程调用时实际通信细节的IPC方法;linux中通过RPC可以充分利用非共享内存的多处理器环境,提高系统资源的利用率。


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function

Dreamweaver Mac version
Visual web development tools

ZendStudio 13.5.1 Mac
Powerful PHP integrated development environment

SublimeText3 Mac version
God-level code editing software (SublimeText3)

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),
