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
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
lqf:x:1000:1000:lqf:/home/lqf:/bin/bash
[root@centos8 ~]# grep -v '/sbin/nologin' /etc/passwd | cut -d: -f1
root
sync
shutdown
halt
lqf
2、查出用户UID最大值的用户名、UID及shell类型
[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 by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin
polkitd:x:998:996:User for polkitd:/:/sbin/nologin
unbound:x:997:995:Unbound DNS resolver:/etc/unbound:/sbin/nologin
sssd:x:996:993:User for sssd:/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
lqf:x:1000:1000:lqf:/home/lqf:/bin/bash
[root@centos8 ~]# cat /etc/passwd | cut -d: -f3
0
1
2
3
4
5
6
7
8
11
12
14
65534
81
999
193
59
998
997
996
74
1000
[root@centos8 ~]# cat /etc/passwd | cut -d: -f3 | sort -nr
65534
1000
999
998
997
996
193
81
74
59
14
12
11
8
7
6
5
4
3
2
1
0
[root@centos8 ~]# cat /etc/passwd | cut -d: -f3 | sort -nr | head -n1
65534