命令简介：
该命令用来列出目前与过去登录系统的用户相关信息。指令英文原义：show listing of last logged in users
执行权限 ：有些需要特殊权限
指令所在路径：/usr/bin/last
执行last指令时，它会读取位于/var/log目录下名称为wtmp的文件，并把该给文件的内容记录的登录系统的用户名单全部显示出来。默认是显示wtmp的记录，btmp能显示的更详细，可以显示远程登录，例如ssh登录。
utmp文件中保存的是当前正在本系统中的用户的信息。
wtmp文件中保存的是登录过本系统的用户的信息。
命令输出字段介绍：
第一列：用户名
第二列：终端位置。pts/0 (伪终端) 意味着从诸如SSH或telnet的远程连接的用户.tty (teletypewriter) 意味着直接连接到计算机或者本地连接的用户
第三列：登录ip或者内核 。如果你看见:0.0 或者什么都没有，这意味着用户通过本地终端连接。除了重启活动，内核版本会显示在状态中。
第四列：开始时间
第五列：结束时间（still login in 还未退出 down 直到正常关机 crash 直到强制关机）
第六列：持续时间
命令语法：
last [-R] [-num] [ -n num ] [-adiowx] [ -f file ] [ -t YYYYMMDDHHMMSS ] [name...] [tty...]
命令参数：
|
参数 |
长参数 |
描叙 |
|
-a |
将登录系统的的主机名称或IP地址，显示在最后一行 |
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-d |
将IP地址转换成主机名称 |
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-f |
指定记录文件，默认是显示/var/log目录下的wtmp文件的记录，但/var/log目录下得btmp能显示的内容更丰富，可以显示远程登录，例如ssh登录 ，包括失败的登录请求。 |
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-i |
-i显示特定ip登录的情况。跟踪用 -i显示特定ip登录的情况。跟踪用 |
|
|
-o |
Read an old-type wtmp file (written by linux-libc5 applications). |
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-n |
-n <显示行数>或-<显示行数> 设置显示多少行记录 |
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-w |
Display full user and domain names in the output |
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-R |
不显示登入系统的主机名称或IP（省略 hostname 的栏位） |
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-t |
显示YYYYMMDDHHMMSS之前的信息 |
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-x |
显示系统关闭、用户登录和退出的历史 |
使用示例：
1：查看last命令的帮助信息
[root@DB-Server ~]# man last
[root@DB-Server ~]# last -h
last: invalid option -- h
Usage: last [-num | -n num] [-f file] [-t YYYYMMDDHHMMSS] [-R] [-x] [-o] [-w] [username..] [tty..]
2：显示最后登录系统的N条记录
[root@DB-Server ~]#last -10
root pts/1 :0.0 Wed Dec 18 09:54 still logged in
root pts/4 :0.0 Wed Dec 18 09:43 - 09:48 (00:04)
root pts/1 :0.0 Wed Dec 18 09:43 - 09:48 (00:05)
root pts/3 192.168.103.79 Wed Dec 18 09:41 - 12:40 (02:59)
root pts/4 :0.0 Wed Dec 18 09:28 - 09:30 (00:01)
root pts/3 :0.0 Wed Dec 18 09:27 - 09:30 (00:02)
root pts/2 192.168.103.29 Wed Dec 18 09:27 still logged in
root pts/1 :0.0 Wed Dec 18 09:27 - 09:42 (00:15)
root pts/2 :0.0 Wed Dec 18 09:23 - 09:25 (00:01)
root pts/1 :0.0 Wed Dec 18 09:22 - 09:25 (00:02)
wtmp begins Wed Dec 11 03:02:17 2013
[root@DB-Server ~]# last -n 10
root pts/1 :0.0 Wed Dec 18 09:54 still logged in
root pts/4 :0.0 Wed Dec 18 09:43 - 09:48 (00:04)
root pts/1 :0.0 Wed Dec 18 09:43 - 09:48 (00:05)
root pts/3 192.168.103.79 Wed Dec 18 09:41 - 12:40 (02:59)
root pts/4 :0.0 Wed Dec 18 09:28 - 09:30 (00:01)
root pts/3 :0.0 Wed Dec 18 09:27 - 09:30 (00:02)
root pts/2 192.168.103.29 Wed Dec 18 09:27 still logged in
root pts/1 :0.0 Wed Dec 18 09:27 - 09:42 (00:15)
root pts/2 :0.0 Wed Dec 18 09:23 - 09:25 (00:01)
root pts/1 :0.0 Wed Dec 18 09:22 - 09:25 (00:02)
wtmp begins Wed Dec 11 03:02:17 2013
3：将登录系统的主机名或IP地址显示在最后一行
[root@DB-Server ~]# last -10 -a
root pts/1 Wed Dec 18 09:54 still logged in :0.0
root pts/4 Wed Dec 18 09:43 - 09:48 (00:04) :0.0
root pts/1 Wed Dec 18 09:43 - 09:48 (00:05) :0.0
root pts/3 Wed Dec 18 09:41 - 12:40 (02:59) 192.168.103.79
root pts/4 Wed Dec 18 09:28 - 09:30 (00:01) :0.0
root pts/3 Wed Dec 18 09:27 - 09:30 (00:02) :0.0
root pts/2 Wed Dec 18 09:27 still logged in 192.168.103.29
root pts/1 Wed Dec 18 09:27 - 09:42 (00:15) :0.0
root pts/2 Wed Dec 18 09:23 - 09:25 (00:01) :0.0
root pts/1 Wed Dec 18 09:22 - 09:25 (00:02) :0.0
wtmp begins Wed Dec 11 03:02:17 2013
4：不显示登入系统的主机名称或IP地址
[root@DB-Server ~]# last -10 -R
root pts/1 Wed Dec 18 09:54 still logged in
root pts/4 Wed Dec 18 09:43 - 09:48 (00:04)
root pts/1 Wed Dec 18 09:43 - 09:48 (00:05)
root pts/3 Wed Dec 18 09:41 - 12:40 (02:59)
root pts/4 Wed Dec 18 09:28 - 09:30 (00:01)
root pts/3 Wed Dec 18 09:27 - 09:30 (00:02)
root pts/2 Wed Dec 18 09:27 still logged in
root pts/1 Wed Dec 18 09:27 - 09:42 (00:15)
root pts/2 Wed Dec 18 09:23 - 09:25 (00:01)
root pts/1 Wed Dec 18 09:22 - 09:25 (00:02)
wtmp begins Wed Dec 11 03:02:17 2013
5: 指定/var/log/btmp文件，查看登录系统的用户相关信息
[root@DB-Server ~]# last -n 10 -f /var/log/btmp
root ssh:notty 192.168.136.163 Fri Oct 17 18:16 gone - no logout
root ssh:notty 192.168.136.163 Fri Oct 17 09:50 - 18:16 (08:26)
root ssh:notty 192.168.136.163 Fri Oct 17 09:50 - 09:50 (00:00)
root ssh:notty 192.168.40.218 Tue Jul 23 17:40 - 09:50 (450+16:10)
root ssh:notty 192.168.236.149 Sun Apr 14 01:34 - 17:40 (100+16:05)
root ssh:notty 192.168.178.147 Fri Mar 8 17:25 - 01:34 (36+08:08)
tomcat ssh:notty get185806.gfg1.e Fri Oct 26 16:48 - 17:25 (133+00:37)
root ssh:notty 192.168.193.3 Mon Oct 22 18:13 - 16:48 (3+22:34)
root ssh:notty 192.168.193.3 Mon Oct 22 18:13 - 18:13 (00:00)
devloper ssh:notty get185819.gfg1.e Wed Oct 17 17:22 - 18:13 (5+00:50)
btmp begins Thu Apr 12 14:30:06 2012
6: 将IP地址转换成主机名称
last -10 -d
7: 显示YYYYMMDDHHMMSS（20150110093000）之前的信息
[root@DB-Server ~]# last -10 -t 20150110093000
root pts/2 192.168.102.186 Fri Jan 9 15:35 - 17:27 (01:52)
root pts/2 192.168.102.134 Thu Jan 8 10:25 - 12:27 (02:02)
root pts/3 192.168.125.53 Tue Jan 6 23:59 - 00:09 (00:09)
root pts/2 192.168.125.53 Tue Jan 6 23:45 - 00:09 (00:23)
root pts/3 192.168.102.88 Tue Jan 6 15:23 - 16:20 (00:57)
root pts/2 192.168.102.88 Tue Jan 6 15:08 - 17:25 (02:16)
oracle pts/1 :2.0 Tue Jan 6 15:07 still logged in
reboot system boot 2.6.32-200.13.1. Tue Jan 6 15:07 (7+20:21)
root pts/2 192.168.102.88 Tue Jan 6 14:47 - down (00:17)
oracle pts/1 :2.0 Tue Jan 6 14:46 - down (00:18)
wtmp begins Wed Apr 11 16:31:10 2012