说在前面的话
1、在kali中metasploit默认使用postgresql作为它的数据库；
想要开启metasploit服务首先得打开postgresql数据库，
命令如下：（或者：/etc/init.d/postgresql start）;
因为在kali中所有的服务都不是默认开机自启的，
所以想要开机自启，命令如下：update-rc.d postgresql enable。
2、初次使用数据库服务时需初始化，以便创建系统默认的数据库及数据库用户；
命令如下：msfdb init（默认创建的数据库名：msf，msf_test;用户名：msf；口令默认为空）
3、接下来就是启动metasploit的时候了；
在kali2.0之后，只需启动msf控制台即可；
命令如下：msfconsole。
（kali2.0之前的命令是这样的：service metasploit start；对于2.0之后不管用）
问题详情
msf > db_status
[*] postgresql selected, no connection
msf >
运行 service Metasploit start 无任何反应，提醒报错：
Failed to start metasploit.service: Unit metasploit.service failed to load: No such file or directory.
解决办法
对于命令解释
msfdb init # initialize the database
msfdb reinit # delete and reinitialize the database
msfdb delete # delete database and stop using it
msfdb start # start the database
msfdb stop # stop the database
root@kali:~# msfdb reinit
Creating database user 'msf'
为新角色输入的口令:
再输入一遍:
Creating databases 'msf' and 'msf_test'
Creating configuration file in /usr/share/metasploit-framework/config/database.yml
Creating initial database schema
root@kali:~# msfdb start
root@kali:~# msfconsole .~+P``````-o+:. -o+:.
.+oooyysyyssyyssyddh++os-````` ``````````````` `
+++++++++++++++++++++++sydhyoyso/:.````...`...-///::+ohhyosyyosyy/+om++:ooo///o
++++///////~~~~///////++++++++++++++++ooyysoyysosso+++++++++++++++++++///oossosy
--.` .-.-...-////+++++++++++++++////////~~//////++++++++++++///
`...............` `...-/////...` .::::::::::-. .::::::-
.hmMMMMMMMMMMNddds\...//M\\.../hddddmMMMMMMNo
:Nm-/NMMMMMMMMMMMMM$$NMMMMm&&MMMMMMMMMMMMMMy
.sm/`-yMMMMMMMMMMMM$$MMMMMN&&MMMMMMMMMMMMMh`
-Nd` :MMMMMMMMMMM$$MMMMMN&&MMMMMMMMMMMMh`
-Nh` .yMMMMMMMMMM$$MMMMMN&&MMMMMMMMMMMm/
`oo/``-hd: `` .sNd :MMMMMMMMMM$$MMMMMN&&MMMMMMMMMMm/
.yNmMMh//+syysso-`````` -mh` :MMMMMMMMMM$$MMMMMN&&MMMMMMMMMMd
.shMMMMN//dmNMMMMMMMMMMMMs` `:```-o++++oooo+:/ooooo+:+o+++oooo++/
`///omh//dMMMMMMMMMMMMMMMN/:::::/+ooso--/ydh//+s+/ossssso:--syN///os:
/MMMMMMMMMMMMMMMMMMd. `/++-.-yy/...osydh/-+oo:-`o//...oyodh+
-hMMmssddd+:dMMmNMMh. `.-=mmk.//^^^\\.^^`:++:^^o://^^^\\`::
.sMMmo. -dMd--:mN/` ||--X--|| ||--X--||
........../yddy/:...+hmo-...hdd:............\\=v=//............\\=v=//.........
================================================================================
=====================+--------------------------------+=========================
=====================| Session one died of dysentery. |=========================
=====================+--------------------------------+=========================
================================================================================ Press ENTER to size up the situation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Date: April , %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%% Weather: It's always cool in the lab %%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%% Health: Overweight %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%% Caffeine: mg %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%% Hacked: All the things %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Press SPACE BAR to continue Validate lots of vulnerabilities to demonstrate exposure
with Metasploit Pro -- Learn more on http://rapid7.com/metasploit =[ metasploit v4.12.41-dev ]
+ -- --=[ exploits - auxiliary - post ]
+ -- --=[ payloads - encoders - nops ]
+ -- --=[ Free Metasploit Pro trial: http://r-7.co/trymsp ] msf > db_status
[*] postgresql connected to msf
msf >
则，可以成功！