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

[root@centos8 data]# grep -v "/sbin/nologin" /etc/passwd |echo "`wc -l`个用户，如下：" && grep -v "/sbin/nologin" /etc/passwd | cut -d: -f1
8个用户，如下：
root
sync
shutdown
halt
thomas
user1
user2
user3
[root@centos8 data]#

2、查出用户UID最大值的用户名、UID及shell类型

[root@centos8 data]# grep `grep -oE "[0-9]+:[0-9]+" /etc/passwd |cut -d: -f1 | sort -nr | head -1` /etc/passwd | cut -d: -f1,3,7
nobody:65534:/sbin/nologin
[root@centos8 data]#

方法一 grep `grep -oE "[0-9]+:[0-9]+" /etc/passwd |cut -d: -f1 | sort -nr | head -1` /etc/passwd 该步骤可能会筛出gid最大的值，得不到想要的结果。仅留做借鉴，建议使用方法2提取 max uid信息即可。

[root@centos8 data]# cut -d: -f1,3,7 /etc/passwd | sort -t: -k2 -nr | head -1
nobody:65534:/sbin/nologin
[root@centos8 data]#

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@centos8 data]# ss -ant -H | grep -oE "([0-9]{1,3}\.){3}[0-9]{1,3}:[0-9]*[[:space:]]*$" | cut -d: -f1 | sort -nr|uniq -c
      4 10.0.0.1
      1 8.43.85.14
[root@centos8 data]#

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

#disk.sh
#!/bin/bash
#********************************************************************
#Author: xxxxxxxxxxxxx
#Date： 2021-12-03 01:17
#FileName： disk.sh
#Description：Shell Script
#********************************************************************

red="\e[1;31m"

green="echo -e \e[1;32m"
end="\e[0m"

disk_max_use=`df -h| grep -vi filesystem| tr  -s ' ' '%'| cut -d'%' -f5| sort -nr |head -1`
disk_name=`df -h |grep $disk_max_use |cut -d' ' -f1`

$green----MAX DISK INFO----------$end
echo -e "$red DISK-NAME: $disk_name $end"
echo -e "$red MAX-USAGE: $disk_max_use% $end"
$green---------------------------$end

运行结果：

[root@centos8 shell-excercise]# bash disk.sh
----MAX DISK INFO----------
 DISK-NAME: /dev/sda5
 MAX-USAGE: 21%
---------------------------
[root@centos8 shell-excercise]#

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

#systeminfo.sh
#!/bin/bash
#********************************************************************
#Author: xxxxxxxxxxxxxx
#Date： 2021-12-03 00:12
#FileName： systeminfo.sh
#Description：Shell Script
#********************************************************************

red="\e[1;31m"
green="echo -e \e[1;32m"
end="\e[0m"

sys_hostname=`hostnamectl |grep hostname | cut -d: -f2`
sys_ipaddr=`ip addr show ens33 |grep -oE "([0-9]{1,3}\.){3}[0-9]{1,3}" |head -1`
os_ver=`cat /etc/os-release |grep -i "pretty_name" |cut -d= -f2`
kernel_ver=`uname -r`
cpu_ver=`cat /proc/cpuinfo |grep -i "model name" | cut -d: -f2 |uniq`
ram_size=`cat /proc/meminfo |grep -i "memtotal" |cut -d: -f2 |tr -s ' '`
disk_size=`lsblk |grep "^sd" |tr -s ' ' |cut -d' ' -f4`

$green-----------------------SystemInfo--------------------------------$end
echo -e "$red HOSTNAME:  $sys_hostname $end"
echo -e "$red IPADDR:     $sys_ipaddr $end"
echo -e "$red OS_VERSION: $os_ver $end"
echo -e "$red KERNEL:     $kernel_ver $end"
echo -e "$red CPU:       $cpu_ver $end"
echo -e "$red RAM SIZE:  $ram_size $end"
echo -e "$red DISK SIZE:  $disk_size $end"
$green-----------------------SystemInfo--------------------------------$end

运行结果：

[root@centos8 shell-excercise]# bash systeminfo.sh
-----------------------SystemInfo--------------------------------
 HOSTNAME:   centos8.magedu.org
 IPADDR:     10.0.0.151
 OS_VERSION: "CentOS Linux 8"
 KERNEL:     4.18.0-305.3.1.el8.x86_64
 CPU:        Intel(R) Core(TM) i5-9400F CPU @ 2.90GHz
 RAM SIZE:   1997772 kB
 DISK SIZE:  200G
-----------------------SystemInfo--------------------------------
[root@centos8 shell-excercise]#

6、20分钟内通关vimtutor（可参考https://yyqing.me/post/2017/2017-02-22-vimtutor-chinese-summary）

vimtutor:

                                   Lesson 1 summary
Lesson 1.1: Moving the cursor 移动
h:⬅  j:⬇  k:⬆  l:➡
Lesson 1.2:  EXITING VIM 退出
1. Press the <ESC> key (make sure in normal mode)
2. Type:     :q!<ENTER> (discarding any changes you have mode)
Lesson 1.3:  TEXT EDITING - DELETION 删除
** Press x  to delete the character under the cursor.**
Lesson 1.4:  TEXT EDITING - INSERTION 插入
** Press i  to insert text.**
Lesson 1.5:  TEXT EDITING - APPENDING 添加
** Press A  to append text.**
Lesson 1.6:  EDITING A FILE   使用 :wq 命令保存并退出
** Use :wq to save file and exit. **

                                 Lesson 2 Summary
1. To delete from the cursor up to the next word type: dw
** dw 从光标处开始删除直至遇到下一个单词 **
2. To delete from the cursor up to the end of a line type: d$ 
** d$ 从光标处开始删除至行末 **
3. To delete a whole line type: dd
** dd 删除光标所在整行 **
4. To repeat a motion prepend it with a number:   2w
** 在动作前面加数字来实现重复操作 **
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
** Normal模式下数字0可以将光标移至行首 **
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
** 小字母u可以撤销上一步操作，大写字母U可以撤销整行的修改，ctrl+r可以恢复刚刚被u撤销的修改**

                                 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).
** Normal模式下，字母p可以将删除的文本粘贴到光标所在位置的后面，如果删除的是一行，则粘贴在光标所在行的下一行位置**
  2. To replace the character under the cursor, type   r   and then the
     character you want to have there.
** Normal模式下，将光标移动至要替换的字母上，键入r，然后再键入想要替换成的字母即可 **
  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.
** Normal模式下，键入ce/c$ 将删除从光标处开始至单词末/行末，并进入Insert模式，输入修改后的内容 **
  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.
**Normal模式下，G定位到文件末行，数字+G定位到指定数字行，gg定位到文件首行。**
  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.
**Normal模式下，键入 /string 或 ?string 来实现字符串向下/向上匹配搜索，n为当前搜索模式下顺序搜索下一个结果，N为反向搜索下一个结果。ctrl+o 定位到光标上一次位置，ctrl-i 定位到光标较目前的下一个位置(如有)。**
  3. Typing  %  while the cursor is on a (,),[,],{, or } goes to its match.
**Normal模式下，当光标在括号等字符上时键入%来定位匹配的字符对。**
  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
**Normal模式下，键入:s/old/new实现对光标所在行的匹配的第一个字符串进行替换，:s/old/new/g实现对光标所在行的匹配的全部字符串进行替换。:#,#s/old/new/g实现对指定的#-#行之间的匹配的全部字符串进行替换。:%s/old/new/g实现对全文匹配的全部字符串进行替换，gc则是增加每个字符串替换前确认提示。**

                                 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.
**Normal模式下，通过键入 :!command 来执行外部的shell命令**
  2.  :w FILENAME  writes the current Vim file to disk with name FILENAME.
**Normal模式下，键入 :w filename 来将当前内容另存为当前目录的 filename 文件中。**
  3.  v  motion  :w FILENAME  saves the Visually selected lines in file
      FILENAME.
**normal模式下通过键入v进入visual模式，在visual模式下选取部分内容后，键入 :w filename 将选取的内容另存为当前目录下的 filename 文件。**
  4.  :r FILENAME  retrieves disk file FILENAME and puts it below the
      cursor position.
**normal模式下，键入 :r filename 来提取当前目录下filename文件内容至光标下位置。**
  5.  :r !dir  reads the output of the dir command and puts it below the
      cursor position.
*Normal模式下，键入 :r !command 将命令command的执行结果提取到光标下位置。**

                                 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.
**Normal模式下，键入小写o来在光标下新开一行并进入Insert模式，大写O则是在上一行。**
  2. Type  a  to insert text AFTER the cursor.
     Type  A  to insert text after the end of the line.
**Normal模式下，键入小写a在光标后进入Insert模式，大写A则是定位到行末并进入Insert模式。**
  3. The  e  command moves to the end of a word.
**Normal模式下，键入e将光标移动至单词末尾处。**
  4. The  y  operator yanks (copies) text,  p  puts (pastes) it.
**Normal模式下，y表示复制，p表示粘贴**
  5. Typing a capital  R  enters Replace mode until  <ESC>  is pressed.
**Normal模式下，键入大写R进入字符连续替换模式直至键入<ESC>返回Normal模式。**
  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
**Normal模式下，键入 :set xxx 来开启 xxx对应的功能，:set noxxx 来关闭。**

                                 Lesson 7 Summary
  1. Type  :help  or press <F1> or <Help>  to open a help window.
**Normal模式下，键入 :help启动帮助文档窗口。**
  2. Type  :help cmd  to find help on  cmd .
**Normal 或帮助文档窗口中，键入 :help cmd 来查找命令 cmd 的帮助信息。**
  3. Type  CTRL-W CTRL-W  to jump to another window
**vim多窗口模式下通过 ctrl+w 来切换窗口。**
  4. Type  :q  to close the help window
**键入 :q 来退出帮助窗口。**
  5. Create a vimrc startup script to keep your preferred settings.
**可以参考 :r $VIMRUNTIME/vimrc_example.vim 来创建自己的vim环境。保存在 ~/.vimrc文件。**
  6. When typing a  :  command, press CTRL-D to see possible completions.
     Press <TAB> to use one completion.
**键入冒号 : 后，可通过ctrl+d 来显示命令选项，通过tab按键来实现命令补齐或切换提示**

vim提高资料参考链接：http://iccf-holland.org/click5.html