1、统计出/etc/passwd文件中其默认shell为非/sbin/nologin的用户个数，并将用户都显示出来
统计非/sbin/nologin用户个数：
~]# grep -v "/sbin/nologin" /etc/passwd | wc -l
显示用户：
~]# grep -v "/sbin/nologin" /etc/passwd | awk -F: ‘{print $1}‘ root sync shutdown halt test
2、查出用户UID最大值的用户名、UID及shell类型
~]# cat /etc/passwd | awk -F: ‘{print $1,$3,$NF}‘|sort -k 2 -nr |head -1 nobody 65534 /sbin/nologin
3、统计当前连接本机的每个远程主机IP的连接数，并按从大到小排序
[root@Centos8Desktop ~]# ss -ant|grep -v LISTEN |grep -v Address|awk ‘{print $5}‘|cut -d: -f1|sort|uniq -c|sort -r 6 10.0.0.1 2 10.0.0.18 1 10.0.0.7 1 10.0.0.16
4、编写脚本disk.sh，显示当前硬盘分区中空间利用率最大的值
[root@Centos8Desktop ~]# df |tr -s " "|cut -d" " -f5|cut -d% -f 1|sort -nr|head -1
22
5、编写脚本 systeminfo.sh，显示当前主机系统信息，包括:主机名，IPv4地址，操作系统版本，内核版本，CPU型号，内存大小，硬盘大小
vim systeminfo.sh
#!/bin/bash echo 主机名: `hostname` echo IP地址: `ifconfig eth0|grep netmask|tr -s " "|cut -d" " -f3` echo 操作系统版本: `grep ^ID= /etc/os-release |cut -d \" -f2``grep ^VERSION= /etc/os-release |cut -d \" -f2` echo 内核版本: `uname -r|cut -d- -f1` echo CPU型号: `lscpu |grep "Model name"|grep -o A.*` echo 内存大小: `free -h|grep Mem|awk ‘{print $2}‘` echo 硬盘大小: `fdisk -l|grep /dev/sd|grep Disk|awk -F [:,] ‘{print $2}‘|tr -d " "`
6、20分钟内通关vimtutor（可参考https://yyqing.me/post/2017/2017-02-22-vimtutor-chinese-summary）
shell输入vimtutor即可进行基本的vim操作练习，根据每一节的指引进行操作，能基本了解vim的一些日常用法。每一章的summary也是很好的总结，摘录如下以供复习查阅。
另外，vim键盘图也是很不错的，可以作为电脑桌面。
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lesson 1 SUMMARY 1. The cursor is moved using either the arrow keys or the hjkl keys. h (left) j (down) k (up) l (right) 2. To start Vim from the shell prompt type: vim FILENAME <ENTER> 3. To exit Vim type: <ESC> :q! <ENTER> to trash all changes. OR type: <ESC> :wq <ENTER> to save the changes. 4. To delete the character at the cursor type: x 5. To insert or append text type: i type inserted text <ESC> insert before the cursor A type appended text <ESC> append after the line NOTE: Pressing <ESC> will place you in Normal mode or will cancel an unwanted and partially completed command. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lesson 2 SUMMARY 1. To delete from the cursor up to the next word type: dw 2. To delete from the cursor to the end of a line type: d$ 3. To delete a whole line type: dd 4. To repeat a motion prepend it with a number: 2w 5. The format for a change command is: operator [number] motion where: operator - is what to do, such as d for delete [number] - is an optional count to repeat the motion motion - moves over the text to operate on, such as w (word), $ (to the end of line), etc. 6. To move to the start of the line use a zero: 0 7. To undo previous actions, type: u (lowercase u) To undo all the changes on a line, type: U (capital U) To undo the undo‘s, type: CTRL-R ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lesson 3 SUMMARY 1. To put back text that has just been deleted, type p . This puts the deleted text AFTER the cursor (if a line was deleted it will go on the line below the cursor). 2. To replace the character under the cursor, type r and then the character you want to have there. 3. The change operator allows you to change from the cursor to where the motion takes you. eg. Type ce to change from the cursor to the end of the word, c$ to change to the end of a line. 4. The format for change is: c [number] motion ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lesson 4 SUMMARY 1. CTRL-G displays your location in the file and the file status. G moves to the end of the file. number G moves to that line number. gg moves to the first line. 2. Typing / followed by a phrase searches FORWARD for the phrase. Typing ? followed by a phrase searches BACKWARD for the phrase. After a search type n to find the next occurrence in the same direction or N to search in the opposite direction. CTRL-O takes you back to older positions, CTRL-I to newer positions. 3. Typing % while the cursor is on a (,),[,],{, or } goes to its match. 4. To substitute new for the first old in a line type :s/old/new To substitute new for all ‘old‘s on a line type :s/old/new/g To substitute phrases between two line #‘s type :#,#s/old/new/g To substitute all occurrences in the file type :%s/old/new/g To ask for confirmation each time add ‘c‘ :%s/old/new/gc ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lesson 5 SUMMARY 1. :!command executes an external command. Some useful examples are: (MS-DOS) (Unix) :!dir :!ls - shows a directory listing. :!del FILENAME :!rm FILENAME - removes file FILENAME. 2. :w FILENAME writes the current Vim file to disk with name FILENAME. 3. v motion :w FILENAME saves the Visually selected lines in file FILENAME. 4. :r FILENAME retrieves disk file FILENAME and puts it below the cursor position. 5. :r !dir reads the output of the dir command and puts it below the cursor position. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lesson 6 SUMMARY 1. Type o to open a line BELOW the cursor and start Insert mode. Type O to open a line ABOVE the cursor. 2. Type a to insert text AFTER the cursor. Type A to insert text after the end of the line. 3. The e command moves to the end of a word. 4. The y operator yanks (copies) text, p puts (pastes) it. 5. Typing a capital R enters Replace mode until <ESC> is pressed. 6. Typing ":set xxx" sets the option "xxx". Some options are: ‘ic‘ ‘ignorecase‘ ignore upper/lower case when searching ‘is‘ ‘incsearch‘ show partial matches for a search phrase ‘hls‘ ‘hlsearch‘ highlight all matching phrases You can either use the long or the short option name. 7. Prepend "no" to switch an option off: :set noic ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Lesson 7 SUMMARY 1. Type :help or press <F1> or <Help> to open a help window. 2. Type :help cmd to find help on cmd . 3. Type CTRL-W CTRL-W to jump to another window 4. Type :q to close the help window 5. Create a vimrc startup script to keep your preferred settings. 6. When typing a : command, press CTRL-D to see possible completions. Press <TAB> to use one completion.