文本处理命令练习

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 ~]# grep -v /sbin/nologin /etc/passwd        #输出默认shell为非/sbin/nologin的用户
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
xuexi:x:1000:1000:xuexi:/home/xuexi:/bin/bash
[root@centos8 ~]# grep -v /sbin/nologin /etc/passwd | cut -d ":" -f1        #输出用户名
root
sync
shutdown
halt
xuexi
[root@centos8 ~]# grep -v /sbin/nologin /etc/passwd | cut -d ":" -f1 | wc -l     #统计用户个数
5
[root@centos8 ~]# 

2、查出用户UID最大值的用户名、UID及shell类型

[root@centos8 ~]# cat /etc/passwd                     #查看所有账户
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
geoclue:x:997:995:User for geoclue:/var/lib/geoclue:/sbin/nologin
rtkit:x:172:172:RealtimeKit:/proc:/sbin/nologin
pipewire:x:996:992:PipeWire System Daemon:/var/run/pipewire:/sbin/nologin
pulse:x:171:171:PulseAudio System Daemon:/var/run/pulse:/sbin/nologin
libstoragemgmt:x:995:989:daemon account for libstoragemgmt:/var/run/lsm:/sbin/nologin
qemu:x:107:107:qemu user:/:/sbin/nologin
usbmuxd:x:113:113:usbmuxd user:/:/sbin/nologin
unbound:x:994:988:Unbound DNS resolver:/etc/unbound:/sbin/nologin
gluster:x:993:987:GlusterFS daemons:/run/gluster:/sbin/nologin
rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin
avahi:x:70:70:Avahi mDNS/DNS-SD Stack:/var/run/avahi-daemon:/sbin/nologin
saslauth:x:992:76:Saslauthd user:/run/saslauthd:/sbin/nologin
dnsmasq:x:985:985:Dnsmasq DHCP and DNS server:/var/lib/dnsmasq:/sbin/nologin
radvd:x:75:75:radvd user:/:/sbin/nologin
sssd:x:984:984:User for sssd:/:/sbin/nologin
cockpit-ws:x:983:982:User for cockpit web service:/nonexisting:/sbin/nologin
cockpit-wsinstance:x:982:981:User for cockpit-ws instances:/nonexisting:/sbin/nologin
chrony:x:981:980::/var/lib/chrony:/sbin/nologin
colord:x:980:979:User for colord:/var/lib/colord:/sbin/nologin
rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin
setroubleshoot:x:979:978::/var/lib/setroubleshoot:/sbin/nologin
flatpak:x:978:977:User for flatpak system helper:/:/sbin/nologin
gdm:x:42:42::/var/lib/gdm:/sbin/nologin
clevis:x:977:976:Clevis Decryption Framework unprivileged user:/var/cache/clevis:/sbin/nologin
gnome-initial-setup:x:976:975::/run/gnome-initial-setup/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
xuexi:x:1000:1000:xuexi:/home/xuexi:/bin/bash
[root@centos8 ~]# cat /etc/passwd | cut -d ":" -f1,3,7                #截取所有用户的账户名、UID及shell类型
root:0:/bin/bash
bin:1:/sbin/nologin
daemon:2:/sbin/nologin
adm:3:/sbin/nologin
lp:4:/sbin/nologin
sync:5:/bin/sync
shutdown:6:/sbin/shutdown
halt:7:/sbin/halt
mail:8:/sbin/nologin
operator:11:/sbin/nologin
games:12:/sbin/nologin
ftp:14:/sbin/nologin
nobody:65534:/sbin/nologin
dbus:81:/sbin/nologin
systemd-coredump:999:/sbin/nologin
systemd-resolve:193:/sbin/nologin
tss:59:/sbin/nologin
polkitd:998:/sbin/nologin
geoclue:997:/sbin/nologin
rtkit:172:/sbin/nologin
pipewire:996:/sbin/nologin
pulse:171:/sbin/nologin
libstoragemgmt:995:/sbin/nologin
qemu:107:/sbin/nologin
usbmuxd:113:/sbin/nologin
unbound:994:/sbin/nologin
gluster:993:/sbin/nologin
rpc:32:/sbin/nologin
avahi:70:/sbin/nologin
saslauth:992:/sbin/nologin
dnsmasq:985:/sbin/nologin
radvd:75:/sbin/nologin
sssd:984:/sbin/nologin
cockpit-ws:983:/sbin/nologin
cockpit-wsinstance:982:/sbin/nologin
chrony:981:/sbin/nologin
colord:980:/sbin/nologin
rpcuser:29:/sbin/nologin
setroubleshoot:979:/sbin/nologin
flatpak:978:/sbin/nologin
gdm:42:/sbin/nologin
clevis:977:/sbin/nologin
gnome-initial-setup:976:/sbin/nologin
sshd:74:/sbin/nologin
tcpdump:72:/sbin/nologin
xuexi:1000:/bin/bash
[root@centos8 ~]# cat /etc/passwd | cut -d ":" -f1,3,7 | sort -t: -k2 -nr | head -1    #以UID大小进行排列并输出UID最大值用户名、UID及shell类型
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@centos8 ~]# netstat -nt
Active Internet connections (w/o servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State      
tcp        0      0 10.0.0.101:22           10.0.0.1:60406          ESTABLISHED
tcp        0      0 10.0.0.101:22           10.0.0.1:60405          ESTABLISHED
[root@centos8 ~]# netstat -nt | grep tcp | tr -s " " ":"|cut -d ":" -f6|sort -nr|uniq -c
      2 10.0.0.1