Detailed explanation of what commands are used to view logs in Linux?

This article mainly introduces the commands for viewing logs in Linux. I hope it will be helpful to friends in need!

First method: View the log of real-time changes (more memory-consuming)

Most commonly used:

##

tail -f filename　　(默认最后10行，相当于增加参数 -n 10)
Ctrl+c 是退出tail命令

Other situations:

##

tail -n 20 filename　　(显示filename最后20行)
tail -n +5 filename　　(从第5行开始显示文件)

Second type: Search logs near keywords

Most commonly used:

cat -n filename |grep "关键字"

Other situations: 　

cat filename | grep -C 5 '关键字' 　　(显示日志里匹配字串那行以及前后5行)
cat filename | grep -B 5 '关键字' 　　(显示匹配字串及前5行)
cat filename | grep -A 5 '关键字' 　　(显示匹配字串及后5行)

Third method: Enter the editor to search: vi(vim)

1. Enter vim editing mode: vim filename

2. Enter "/keyword" and press enter to find

##3 , search for the next one, press "n" to exit: After pressing the ESC key, and then entering the : sign, vi will wait for us to enter the command at the bottom of the screen

wq! Save and exit;

q! Exit without saving;

Other situations :

/关键字
  　　注：正向查找，按n键把光标移动到下一个符合条件的地方
?关键字
  　　注：反向查找，按shift+n 键，把光标移动到下一个符合条件的

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