Rhcsa note 4

1. File content browsing

a.cat see /etc/passwd The contents of the document , And output with line number

 b. Use more/less see /etc/passwd Content , And each page displays 10 That's ok

  c. Use head/tail Before viewing the files separately 5 Line content and after 5 Row content

  d. Use grep see /etc/passwd neutralization root Related content

 2.cut Command to use

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

Use the default delimiter to cut the contents of the file , And output the contents of the cut file in the first field after cutting

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 ： The contents are as follows , Output the contents of the first field and the third field

 3.uniq Command to use

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

Use uniq The command counts the number of repetitions

 4.sort command

Given the file num.txt, args.txt
The contents of the document :num.txt
      1
      3
      5
      2
      4
  The contents of the document :args.txt
     test
     args1
     args2
     args4
     args4
     args3

  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
    No Name    Score
    1 zhang 20
    2 li  80
    3 wang 90
    4 sun  60

 5.

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

take hello 123 world 456 Replace letters and spaces in , Just keep the numbers