0716RHCSA

One 、 File content browsing

1）cat see /etc/passwd The contents of the document , And output with line number ：

 2） Use more/less see /etc/passwd Content , And each page displays 10 That's ok ：

3） Use head/tail Before viewing the files separately 5 Line content and after 5 Row content ：4） Use grep see /etc/passwd neutralization root Related content ：  Two 、cut command ：

 Given the file cut_data.txt And the content is ：
No Name Score
1 zhang 20
2 li 80
3 wang 90
4 sun 60
 Text when cutting according to the specified delimiter ：
No|Name|Score
1|zhang|20
2|li|80
3|wang|90
4|sun|60

•   Use the default delimiter to cut the contents of the file , And output the first field after cutting
•   Cut file content , And output the first field and the third field after cutting
• Cut by byte ： Output the first byte to the second byte of the cut 10 Bytes of content
• Cut by character ： Output the first character and the second character after cutting 5 The content of a character
• Cut according to the specified delimiter , Output the contents of the first field and the third field

3、 ... and 、uniq command ： 

 New file uniq_data.txt, The content of the document is 
Welcome to Linux
Windows
Windows
Mac
Mac
Linux

Use uniq The command outputs the result after de duplication  

  Use uniq The command outputs only duplicate lines  

  Use uniq The command outputs non repeating lines

send uniq The command counts the number of repetitions   Four 、sort command ： 

 New file  num.txt, args.txt
 The contents of the document :num.txt
（ There are two spaces ）1
3
5
2
4
 The contents of the document :args.txt
test
args1
args2
args4
args4
args3
 Given the file info_txt： Press the second column as key Sort 
No Name Score
1 zhang 20
2 li 80
3 wang 90
4 sun 60

Yes num.txt Sort , And output the results to sorted_num.txt in Yes args.txt Sort , And output the results to sorted_args.txt in   Yes num.txt and args.txt Sort , And output the results to sorted_merge.txt in  

Yes args.txt After sorting, de re output Merge sorted_args.txt and sorted_num.txt And output Given the file info_txt： Press the second column as key Sort   5、 ... and 、tr command ：

• take 26 After a lowercase letter 13 Replace the first letter with a capital letter

• take hello 123 world 456 Replace the numbers in with empty characters （ Prompt to use wildcards ）

   

• take hello 123 world 456 Replace letters and spaces in , Just keep the numbers ( Prompt to use wildcards )