【Linux】文本处理及Shell编程

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 ~]# cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:65534:65534:Kernel Overflow User:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
systemd-coredump:x:999:997:systemd Core Dumper:/:/sbin/nologin
systemd-resolve:x:193:193:systemd Resolver:/:/sbin/nologin
tss:x:59:59:Account used for TPM access:/dev/null:/sbin/nologin
polkitd:x:998:996:User for polkitd:/:/sbin/nologin
libstoragemgmt:x:997:994:daemon account for libstoragemgmt:/var/run/lsm:/sbin/nologin
unbound:x:996:992:Unbound DNS resolver:/etc/unbound:/sbin/nologin
clevis:x:995:991:Clevis Decryption Framework unprivileged user:/var/cache/clevis:/sbin/nologin
cockpit-ws:x:994:990:User for cockpit web service:/nonexisting:/sbin/nologin
cockpit-wsinstance:x:993:989:User for cockpit-ws instances:/nonexisting:/sbin/nologin
sssd:x:992:988:User for sssd:/:/sbin/nologin
setroubleshoot:x:991:987::/var/lib/setroubleshoot:/sbin/nologin
chrony:x:990:986::/var/lib/chrony:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
user1:x:1000:1000::/home/user1:/bin/bash

[root@CentOS8 ~]# cat /etc/passwd | grep '/sbin/nologin$'
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:65534:65534:Kernel Overflow User:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
systemd-coredump:x:999:997:systemd Core Dumper:/:/sbin/nologin
systemd-resolve:x:193:193:systemd Resolver:/:/sbin/nologin
tss:x:59:59:Account used for TPM access:/dev/null:/sbin/nologin
polkitd:x:998:996:User for polkitd:/:/sbin/nologin
libstoragemgmt:x:997:994:daemon account for libstoragemgmt:/var/run/lsm:/sbin/nologin
unbound:x:996:992:Unbound DNS resolver:/etc/unbound:/sbin/nologin
clevis:x:995:991:Clevis Decryption Framework unprivileged user:/var/cache/clevis:/sbin/nologin
cockpit-ws:x:994:990:User for cockpit web service:/nonexisting:/sbin/nologin
cockpit-wsinstance:x:993:989:User for cockpit-ws instances:/nonexisting:/sbin/nologin
sssd:x:992:988:User for sssd:/:/sbin/nologin
setroubleshoot:x:991:987::/var/lib/setroubleshoot:/sbin/nologin
chrony:x:990:986::/var/lib/chrony:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin

[root@CentOS8 ~]# cat /etc/passwd | grep -v '/sbin/nologin$'
root:x:0:0:root:/root:/bin/bash
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
user1:x:1000:1000::/home/user1:/bin/bash
[root@CentOS8 ~]# cat /etc/passwd | grep -v '/sbin/nologin$' | wc -l
5
[root@CentOS8 ~]# cat /etc/passwd | grep -v '/sbin/nologin$' | cut -d: -f1
root
sync
shutdown
halt
user1

2、查出用户UID最大值的用户名、UID及shell类型

[root@CentOS8 ~]# grep "\<`cat /etc/passwd | cut -d: -f3 | sort -rn | head -n 1`\>" /etc/passwd
nobody:x:65534:65534:Kernel Overflow User:/:/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@CentOS8 ~]# netstat -ant
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 10.0.0.8:22             10.0.0.4:52422          TIME_WAIT
tcp        0     52 10.0.0.8:22             10.0.0.1:49396          ESTABLISHED
tcp        0      0 10.0.0.8:22             10.0.0.4:52428          ESTABLISHED
tcp        0      0 10.0.0.8:22             10.0.0.1:58257          ESTABLISHED
tcp        0      0 10.0.0.8:22             10.0.0.4:52424          TIME_WAIT
tcp        0      0 10.0.0.8:22             10.0.0.4:52430          ESTABLISHED
tcp        0      0 10.0.0.8:22             10.0.0.4:52426          TIME_WAIT
tcp        0      0 10.0.0.8:22             10.0.0.4:52360          ESTABLISHED
tcp6       0      0 :::22                   :::*                    LISTEN
[root@CentOS8 ~]# netstat -ant |grep "ESTABLISHED" | tr -s ' ' | cut -d" " -f5 | grep -Eo "([0-9]{1,3}\.){3}[0-9]"|sort | uniq -c | sort -nr
      3 10.0.0.4
      2 10.0.0.1
[root@CentOS8 ~]# 

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@CentOS8 data]# df -Th
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  372M     0  372M   0% /dev
tmpfs               tmpfs     392M     0  392M   0% /dev/shm
tmpfs               tmpfs     392M  5.7M  386M   2% /run
tmpfs               tmpfs     392M     0  392M   0% /sys/fs/cgroup
/dev/mapper/cl-root xfs       5.0G  2.0G  3.1G  40% /
/dev/mapper/cl-data xfs       3.0G   54M  3.0G   2% /data
/dev/nvme0n1p1      xfs      1014M  202M  813M  20% /boot
tmpfs               tmpfs      79M     0   79M   0% /run/user/0


[root@CentOS8 data]# vim disk.sh
#!/bin/bash
#This script is for check Maximum disk partition usage information
#############################
MAX_Usage=`df -Th | grep -Eo "[0-9]{1,3}\%" | sort -rn | head -1`
MAX_File=`df -Th | grep $MAX_Usage | cut -d' ' -f1`

echo -e "\033[1;32mMaximum disk usage partition information\033[0m"
echo -e  "MAX_Usage:    \033[1;31m $MAX_Usage\033[0m"
echo -e  "MAX_File:     \033[1;31m $MAX_File\033[0m"


[root@CentOS8 data]# chmod a+x disk.sh
[root@CentOS8 data]# ./disk.sh
Maximum disk usage partition information
MAX_Usage:     40%
MAX_File:     /dev/mapper/cl-root

[root@CentOS8 data]# dd if=/dev/zero of=/data/file bs=1M count=2500
2500+0 records in
2500+0 records out
2621440000 bytes (2.6 GB, 2.4 GiB) copied, 2.09592 s, 1.3 GB/s
[root@CentOS8 data]# df -Th
Filesystem          Type      Size  Used Avail Use% Mounted on
devtmpfs            devtmpfs  372M     0  372M   0% /dev
tmpfs               tmpfs     392M     0  392M   0% /dev/shm
tmpfs               tmpfs     392M  5.7M  386M   2% /run
tmpfs               tmpfs     392M     0  392M   0% /sys/fs/cgroup
/dev/mapper/cl-root xfs       5.0G  2.0G  3.1G  40% /
/dev/mapper/cl-data xfs       3.0G  2.5G  505M  84% /data
/dev/nvme0n1p1      xfs      1014M  202M  813M  20% /boot
tmpfs               tmpfs      79M     0   79M   0% /run/user/0
[root@CentOS8 data]# ./disk.sh
Maximum disk usage partition information
MAX_Usage:     84%
MAX_File:     /dev/mapper/cl-data

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

[root@CentOS8 data]# vim system_info.sh 

#!/bin/bash
#打印输出系统信息：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
#
#Copyright (C): janzen@q All rights reserved

RED="\033[1;31m"
GREEN="\033[1;32m"
White="\033[0m"
HostName=`hostname`
IP=`hostname -I`
[[ -e /etc/redhat-release ]] && OSVersion=`cat /etc/redhat-release` || OSVersion=`cat //etc/issue | grep -v ^$ | cut -d'\' -f1`
CPU=`lscpu | grep "^Model name:" | tr -s ' ' | cut -d":" -f2 | grep -Eo "[A-Za-z0-9].*"`
MEM=`free -h | grep Mem | tr -s " " | cut -d' ' -f2`
DISK=`lsblk |tr -s ' ' |grep "disk $" | cut -d' ' -f4`
DISK=`echo $DISK`

echo -e "\033[1;33m-------------System Info----------------$White"
echo -e "${RED}Hostname:        $GREEN$HostName$White"
echo -e "${RED}IP:              $GREEN$IP$White"
echo -e "${RED}OS_Version:      $GREEN$OSVersion$White"
echo -e "${RED}CPU:             $GREEN$CPU$White"
echo -e "${RED}MEM:             $GREEN$MEM$White"
echo -e "${RED}DISK:            $GREEN$DISK$White"
echo -e "\033[1;33m-------------------End-------------------$White"

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