shell-4-Let the text fly

1. Regular expressions

^	Line Start flag
$	End of line Mark
.	Match any one character
[ ]	Match any one of the characterscontained in [ character ] ,Coo[kl] matches Cook or Cool
[^]	Match any one character except [^ character ]
[-]	Matches any one of the characters in the range []
?	Match previous item once or 0 times
+	Match a previous item one or more times
*	Match previous Items 0 or more times
()	Create a substring for matching
N	Matches the previous item n times
{N,m}	Specifies the minimum and maximum number of times the previous item must match
|	Alternate - match | any one of the two sides
\	Escape character to escape the above symbol

2.grep

(1) Search for lines of text that contain a specific pattern

Cat 1 . txt this is a test2  One  -  -  -  -  grep3 1 You can also search for multiple files:grep 3 1 2 3 . txt using regular expressions must use the Egrep

(2) To print all rows except a row

grep 3 1 . txt this is a test2  One  -  -  -

(3) The number of lines in the statistics text or text containing matching strings

grep 3 1  1

(4) Print the number of lines that contain matching strings

grep 3 1  4:

(5) Search multiple files and find out which file the matching text is in

grep 3 1 2  1.txt2. txt

(6) If you are querying recursively, you can use the

grep "Text". -r-n

(7) Ignore case in style (grep-i pattern file)

(8) match multiple styles with grep

grep -E "pattern1"-E "pattern2"

(9) Specifying or excluding files in grep search

grep "Main ()". -R--exclude "Readne"

(10) Print out lines before or after matching text

To print 3 rows after matching a result, you can use the-a option

seq Ten| grep 5 3 5 6 7 8

To print 3 rows before matching a result, you can use the-B option

seq Ten| grep 5 3 2 3 4 5 to print 3 rows before and after matching a result, use -seq| grep 5 3 2 3 4 5 6 7 8

3. Splitting text by column with cut

Cut 2,3 filename

4.sed

（1SED can replace strings in the given textsed' S/pattern/replace_string 'file(2By default, SED will print only the replaced text, and if you want to keep the changes, use-i optionsed-I. ' S/pattern/replace_string 'file(3If you want to replace all content, add the parameter G at the endsed' S/pattern/replace_string/g 'file(4) Remove Blank linessed'/^$/d 'file(5) is replaced directly in the filesed' S/pattern/replacement '-I filename (6) combine multiple expressionssed' Expression ' |sed' expression '=sed' Expression;expression '=sed-E ' expression '-e ' expression '

5.awk

the basic structure of the script is as follows: awk file awk ' BEGIN {statements} {statements} END {END statements} '

6. Statistical frequency in specific documents

#!/bin/bash# Use: Calculates the word frequency of words in a fileif[$#-ne1 ]; Then  Echo "usage:$0 filename"; Exit-1fifilename=$1Egrep-O"\b[[:alpha:]]+\b"$filename | awk '{count[$0]++}end{printf ("%-14s%s\n","Word","Count"); for(Indinchcount) {printf ("%-14s%d\n", Ind,count[ind]); }}'~[email protected] shell]#SHWord_freq.SH/tmp/1. txt Word counta1 This1 is1

7. Merging multiple files by column (paste)

1 2 . txt is a test2    cairui    xijinpng    Aiyinsitan  about            

8. Print the nth Word or column in a file or line

Print the 5th column below awk ' {print $5 } ' filename

9. Print the text between lines or styles

(1) [[email protected] tmp]# seq 100|awk ' nr==4,nr==8 '

(2) 4awk ' nr==m,nr==n ' filename

5

6

7

8

shell-4-Let the text fly