sort命令：
sort [OPTION]... [FILE]...
-f: 忽略字符大小写 --ignore-case fold lower case to upper case characters
-r: 逆序
-t DELIMITER: 字段分隔符
-k #：以指定字段为标准排序
-n: 以数值大小进行排序
-u: uniq，排序后去重
[root@ansible ~]# sort -t : -k 3 -nr /etc/passwd
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
halt:x:7:0:halt:/sbin:/sbin/halt
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
sync:x:5:0:sync:/sbin:/bin/sync
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
bin:x:1:1:bin:/bin:/sbin/nologin
root:x:0:0:root:/root:/bin/bash
