Linux命令——getent

简介

getent命令帮助用户administrative databases中查找相关信息。administrative databases包括：

• • passwd – can be used to confirm usernames, userids, home directories and full names of your users
  • group – all the information about Unix groups known to your system
  • services – all the Unix services configured on your system
  • networks – networking information – what networks your system belongs to
  • protocols – everything your system knows about network protocols

一般语法

getent database [key ...]

getent会在上面数据库中产找key对应的value

举例

查找hostname对应的IP

ubuntu$ getent hosts ubuntu
127.0.1.1       ubuntu
192.168.0.2     ubuntu

执行反响DNS查询（即根据域名查找对应IP）

$ getent hosts myhost.mydomain.com
15.77.3.40       myhost.mydomain.com myhost

根据用户名查找UID

ubuntu$ getent passwd greys
greys:x:1000:1000:Gleb Reys,,,:/home/greys:/bin/bas

根据UID查找用户名

ubuntu$ getent passwd 1000
greys:x:1000:1000:Gleb Reys,,,:/home/greys:/bin/bash

获取当前登陆用户的信息

$ getent passwd `whoami`
root:x:0:0:root:/root:/bin/bash

查找那个服务在使用特定端口

$ getent services 22
ssh                   22/tcp
$ getent services 21
ftp                   21/tcp
$ getent services 25
smtp                  25/tcp mail