Several common text processing tools under Linux

1. Several common text-processing commands

1.cat
Cat we were one of the most common commands in early learning, but we used only the cat command itself, such as cat/etc/passwd, to view the contents of/etc/passwd, no cat option, in fact, the cat command is an option, but we do not use much, The specific parameters are as follows:
First use Vim to edit a simple text, HelloWorld, the content is HelloWorld, here just to show, the specific use of VIM will be described below.

cat /app/block/helloworld                                                                                                //查看helloworld文本内容

- e view text when displaying Liux newline characters in text $

cat /app/block/helloworld                                                                                                //显示helloworld中的换行符$

- v displays line breaks in Windows when viewing Windows text ^m
Use the RZ command to upload helloworld.txt to/app/block in the Windows system.

cat /app/block/helloworld.txt                                                                                           //显示helloworld.txt中的换行符^M

- t display tab

cat -T /app/block/helloworld                                                                                            //显示helloworld中的Tab

- N Displays the result before adding the line number

cat -n /app/block/helloworld                                                                                            //显示的helloworld中增加行号

- b Displays the result before the line number is incremented, but the blank line does not participate in the number

cat -b /app/block/helloworld                                                                                            //helloworld中的空行不编号

-S compression continuous blank line into a row
Need to add a few blank lines after the text

cat -s /app/block/helloworld                                                                                            //压缩helloworld中连续空行为一行

2.tac
The tar command has only one function, which is to display the contents of the text in reverse order

tac /app/block/helloworld                                                                                                //倒序显示helloworld

3.rev
Rev also features only one, that is, the content of the standard input is displayed backwards in each line, supporting the pipeline.

cat /app/block/helloworld|rev                                                                                          //helloworld每行倒着显示

4.head
Head has two commonly used parameters, head is the meaning of the header, is the text of the head part of the operation.
-N Prints the nth line at the beginning of the text

cat /app/block/helloworld|head -1                                                                                   //打印helloworld的第一行

- c N takes the first n bytes of a character

echo helloworld|head -c 5                                                                                              //取helloworld的前5个字节

5.tail
Tail is similar to head, there are also two commonly used parameters, but tail is the tail meaning, is to manipulate the text tail.
-N Prints the line at the end of the text

cat /app/block/helloworld|tail -1                                                                                      //打印helloworld的最后一行

- c N takes the latter n bytes of a character

echo helloworld|tail -c 5                                                                                                 //     取helloworld的后5个字节

Tail takes the last n characters containing the newline character $.
6.cut
Cut is the meaning of cut, cut the text content, the general commonly used options are four, and,-d,-f, general use

- D+ parameter 1 (d + no space in middle)-f+ parameter 2 with parameter 1 as the delimiter, cut the parameter 2 column
Hellow text

cat /app/block/helloworld|cut -d‘ ‘ -f1                                                                               //取出helloworld中以空格为间隔的第一列

The- f option allows you to specify a range and is not necessarily a parameter, such as:

cat /app/block/helloworld|cut -d‘ ‘ -f1-3, 5                                                                      //取出helloworld中以空格为间隔的第一列到第三列和第5列

- C m/m-n/m-n,k Remove the m/m-n/m-n,k character from the string

echo hi hello world i am fun|cut -c 1-3,5                                                                        //显示字符串中第1-3，和第五个字符

cut--output-delimiter= "#" output delimiter
7.past
The functions of the Paste command are used for merging, can be used alone, or can be used with options, there are two options

paste /app/block/helloworld /app/block/helloworld.txt                                                    //合并helloworld和helloworld.txt

- d ' Q ' F1 F2 merged with Q as the delimiter, Q can be any character

paste -d‘|‘ /app/block/helloworld /app/block/helloworld.txt                                              //合并helloworld和helloworld.txt，并用|作为间隔符

- s changes multiline content lines to rows

paste -s /app/block/helloworld                                                                                        //将helloworld中的多行内容变为一行

8.wc
-L Displays the number of lines of text

cat /app/block/helloworld|wc -l                                                                                         //显示helloworld的行数

-M displays the number of characters in the text

cat /app/block/helloworld |wc -m                                                                                      //显示helloworld中的字符数

-C Displays the number of bytes in the text

cat /app/block/helloworld |wc -c                                                                                       //显示helloworld中的字节数

-W Displays the number of words in the text

cat /app/block/helloworld |wc -w                                                                                      //显示helloworld中的单词数

-L Displays the length of the longest line in the text

cat /app/block/helloworld |wc -L                                                                                       //显示helloworld中最长行的长度

2. Text of the Three Musketeers grep

grep is a text-processing tool that filters text and only filters out the content, and he has these options:
The-V keyword displays rows that do not contain a key word,

cat /app/block/helloworld|grep -v hello                                                                            //过滤出不包含hello的行

-I keyword ignores the capitalization of keywords

cat /app/block/helloworld|grep -i hello                                                                            //过滤出hello，并且不区分其中字母的大小写

-N Displays the result of adding line numbers before each line

cat /app/block/helloworld |grep -n hello                                                                         //过滤出含有hello的行，并且在结果上加上行号

-C displays only the number of rows found for the result

cat /app/block/helloworld |grep -c hello                                                                          //过滤hello但不现实结果，只显示过滤出hello的行数

-O displays only keywords that match to, and does not display other content from peers

cat /app/block/helloworld |grep -o hello                                                                          //只显示过滤出的关键字hello，不现实其他的内容

-A # Displays the key line and the down n rows

cat /app/block/helloworld |grep -A2 hello                                                                       //过滤出包含hello的行以及其下一行

-B # Displays the line of keywords and the n rows up

cat /app/block/helloworld |grep -B hello                                                                          //过滤出包含hello的行以及上一行

-C # Displays key lines and n rows up and down n rows

cat /app/block/helloworld |grep -C1 hello                                                                       //过滤出包含hello的行以及其下一行和上一行

-e keyword 1-e keyword 2 ... Relationships between multiple keywords Yes or

cat /app/block/helloworld |grep -e hello -e Hello                                                             

-W keyword matches entire word

cat /app/block/helloworld |grep -w hello                                                                          //过滤出只含有hello单词的行

-e equals egrep using extended regular expressions
Plus-e or using EGREP filtering means using extended regular expressions
-F equals fgrep does not use regular expressions
Regular expressions are described in the next blog post.

Several common text processing tools under Linux