第四周作业—N42-虚怀若谷

一、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@centos7 ~]# grep -v "/sbin/nologin" /etc/passwd|cut -d: -f1
root
sync
shutdown
halt
hovin
[root@centos7 ~]# grep -v "/sbin/nologin" /etc/passwd|cut -d: -f1|wc -l

二、查出用户UID最大值的用户名、UID及shell类型

[root@centos7 ~]# cut -d : -f ,, /etc/passwd|sort -t : -k  -nr|head -n
nfsnobody::/sbin/nologin

三、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@centos7 ~]# w -h    #查询连接数
root     pts/    192.168.214.1    :    .00s  .12s  .00s w -h
root     pts/    192.168.214.1    :    :   .03s  .00s less -s
root     pts/    172.16.236.130   :    :   .02s  .02s -bash
[root@centos7 ~]# w -h|tr -s " "      #压缩空格方便进一步处理
root pts/ 192.168.214.1 : .00s .12s .00s w -h
root pts/ 192.168.214.1 : : .02s .02s -bash
root pts/ 172.16.236.130 : : .02s .02s -bash
[root@centos7 ~]# w -h|tr -s " "|cut -d " " -f     #取出IP地址
192.168.214.1
192.168.214.1
172.16.236.130
[root@centos7 ~]# w -h|tr -s " "|cut -d " " -f |sort   #排序
192.168.214.1
192.168.214.1
172.16.236.130
[root@centos7 ~]# w -h|tr -s " "|cut -d " " -f |sort|uniq -c     #去重并计数
       172.16.236.130
       192.168.214.1
[root@centos7 ~]# w -h|tr -s " "|cut -d " " -f |sort|uniq -c|sort -nr  #按计数逆序
       192.168.214.1
       172.16.236.130

四、编写脚本createuser.sh，实现如下功能：使用一个用户名作为参数，如果指定参数的用户存在，就显示其存在，否则就添加之；显示添加的用户的id号等信息

[root@centos7 scripts]# cat createuser.sh
#!/bin/bash

#read -p "please input a username: " USER
USER=$

if [ -z "$USER" ];then
    echo "Usage: `basename $0` username"
    exit
fi

if id $USER &> /dev/null ;then
    echo "user: $USER already exists"
    exit
else
    useradd $USER
    echo "user: $USER create success"
    id $USER
fi
[root@centos7 scripts]# bash createuser.sh
Usage: createuser.sh username
[root@centos7 scripts]# bash createuser.sh hovin
user: hovin already exists
[root@centos7 scripts]# bash createuser.sh alice
user: alice create success
uid=(alice) gid=(alice) groups=(alice)

五、编写生成脚本基本格式的脚本，包括作者，联系方式，版本，时间，描述等

　　在.vimrc中定义，对创建的以.sh结尾的脚本应用，相关代码如下：

[root@centos7 ~]# cat .vimrc
set tabstop=
autocmd BufNewFile *.sh exec ":call SetTitle()"
func SetTitle()
    if expand("%:e") == sh
    call setline(,"#/bin/bash")
    call setline(,"#")
    call setline(,"#***************************************************")
    call setline(,"Author:                hovin")
    call setline(,"QQ:                    405001597")
    call setline(,"Date:                ".strftime("%Y-%m-%d"))
    call setline(,"FileName:            ".expand("%"))
    call setline(,"Description:        The test script")
    call setline(,"Copyright (C):        ".strftime("%Y")." ALL rights reserved)
    call setline(,"#**************************************************")
    call setline(,"")
    endif
endfunc
autocmd BufNewFile * normal G

[root@centos7 ~]# vim test.sh 　　#创建脚本

#/bin/bash

#

#***************************************************

Author:             hovin

QQ:                 405001597

Date:               2019-11-23

FileName:           test.sh

Description:        The test script

Copyright (C):      2019 ALL rights reserved

#**************************************************