Question

我需要一个sed regex命令，该命令会在一段时间内输出以“ html”结尾且不以“ a”开头的每一行。

我当前的代码可以工作吗？

#include <iostream>
#include <fstream>
using namespace std;

int main() {
    ofstream outfile;
    outfile.open("afile.dat");

    float a[6];

    for (int i=0;i<6; i++){
        outfile <<a[i]<<endl;
    }

    outfile.close();
    return 0;
}

Answer 1

sed命令应为

sed -n '/^[^a].*html$/p'

但是打印匹配行的规范命令是grep：

grep '^[^a].*html$'

Answer 2

Sed刚刚使事情变得复杂...您可以使用grep轻松地处理它！

egrep "^[^a].+\.html$" -f sourcefile > text.txt
//loads file from within the program egrep

egrep "^[^a].+\.html$" < sourcefile > text.txt
//Converts stdin file descriptor with the input redirect 
//to sourceFile for this stage of the` pipeline

在功能上等效。

或

pipe input |  xargs -n1 egrep "^[^a].+\.html$" > text.txt

//xargs  -n1 means take the stdin from the pipe and read it one line at a time in conjunction with the single command specified after any other xargs arguments
// ^ means from start of line, 
//. means any one character
//+ means the previous matched expression(which can be a 
//(pattern group)\1 or [r-ange], etc) one or more times
//\. means escape the single character match and match the period character

//$ means end of line(new line character)
//egrep is short for extended regular expression matches which are really

好（假设您没有使用烟斗或猫等）

您可以使用以下命令将换行符分隔的文件转换为单个输入行：

cat file | tr -d '\n' ' '
//It converts all newlines into a space!

无论如何，通过简单的实用程序来发挥创造力，您可以做很多事情：

xargs，grep，tr是易于学习的好组合。没有这一切的静

Answer 3

请勿对sed执行此操作。用两个不同的grep调用来完成

grep -v ^a file.txt | grep 'html$'

第一个grep获取所有不以“ a”开头的行，并将其输出发送到第二个grep，第二个grep提取所有以“ html”结尾的行。

sed regex命令输出以html结尾的行？

3 个答案: