口令文件

其实我觉得叫密码文件也可以，

 

strptime，strftime完成字符串和struct tm { day， month， year等等}的转换

finger 命令，需要安装

阴影口令

阴影口令，其实就是存储用户名和密码加密信息的文件

查看文件:

sudo cat /etc/shadow
root:$6$drbtofiPuQIhvTu3$Z6OjGV0Pbdn2AUUsxeyfCKRVpDYCQaSNGpKZQ3Qbv6DASW36J.2IWazgsrJVtk0R5efvnoSPbMhNZHk8WpIos1:18866:0:99999:7:::
daemon:*:18375:0:99999:7:::
bin:*:18375:0:99999:7:::
sys:*:18375:0:99999:7:::

组文件

查看 /etc/group，adm那一行，就有多个用户syslog和ubuntu

ubuntu@ubun2004:/etc$ cat /etc/group
root:x:0:
daemon:x:1:
bin:x:2:
sys:x:3:
adm:x:4:syslog,ubuntu
tty:x:5:

附属组ID

一个用户会参与多个项目，从而属于多个组，因此有附属组的概念，

last utmp/wtmp 查询最近用户登录时间

ubuntu@ubun2004:~/work/xv6-labs-2020$ last wtmp

wtmp begins Thu Apr 23 14:41:14 2020
ubuntu@ubun2004:~/work/xv6-labs-2020$ who utmp
ubuntu@ubun2004:~/work/xv6-labs-2020$ last utmp

wtmp begins Thu Apr 23 14:41:14 2020
ubuntu@ubun2004:~/work/xv6-labs-2020$ vim /var/log/wtmp 
ubuntu@ubun2004:~/work/xv6-labs-2020$ cat /var/log/wtmp 
~~~reboot5.4.0-26-genericJ�^��:0ubuntu:0��^��5~~~runlevel5.4.0-26-generic��^[a~~~shutdown5.4.0-26-genericx�^*|~~~reboot5.4.0-26-generic~�^��5~~~runlevel5.4.0-26-generic��^F�pts/0ts/0ubuntu192.168.1.1��^Qa�pts/0��^¡~~~shutdown5.4.0-26-generic��^8v~~~reboot5.4.0-26-generic��^X�5~~~runlevel5.4.0-26-generic��^;
pts/0ts/0ubuntu192.168.1.1��^��
��
~~~shutdown5.4.0-26-generic��^�
                              ~~~reboot5.4.0-26-genericj�^/5~~~runlevel5.4.0-26-generic��^�ALpts/0ts/0ubuntu192.168.1.1��^�8�Lpts/0��^9~~~shutdown5.4.0-26-gG:0ubuntu:0�Z�`��~~~reboot5.8.0-59-generic�(�`-�5~~~runlevel5.8.0-59-generic�(~~~reboot5.8.0-59-generic���`�}5~~~runlevel5.8.0-59-genericƕ�`&��:0ubuntu:0Ε�`Y�~~~reboot5.8.0-63-generic��
                             ae!
5~~~runlevel5.8.0-63-generic��
�:0ubuntu:0��                 a�w
             a�l~~~shutdown5.8.0-63-generic�Oa�
                                               ~~~reboot5.11.0-25-generic�Oa��5~~~runlevel5.11.0-25-generic�Oa�&�:0ubuntu:0�OaL�~~~reboot5.11.0-25-genericaH"5~~~runlevel5.11.0-25-generica�_�:0ubuntu:00au&
                                                ~~~shutdown5.11.0-25-genericLK$a`�~~~reboot5.11.0-27-generi�(a/Z	5~~~runlevel5.11.0-27-generic�(aX��:0ubuntu:0F�(aw�
             ~~~reboot5.11.0-27-generic�1;aw�5~~~runlevel5.11.0-27-generic�1;a��:0ubuntu:0�1;an�~~~reboot5.11.0-34-generic�LEa�%5~~~runlevel5.11.0-34-generic�LEa�a
ubuntu@ubun2004:~/work/xv6-labs-2020$ cat /var/run/utmp 
~~~reboot5.11.0-34-generic�LEa�%5~~~runlevel5.11.0-34-generic�LEa�a

uname查询操作系统信息:

ubuntu@ubun2004:~/work/xv6-labs-2020$ uname -a
Linux ubun2004 5.11.0-34-generic #36~20.04.1-Ubuntu SMP Fri Aug 27 08:06:32 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

hostname用来查询主机在TCP/IP上的网络地址

我的主机名是ubun2004，地址127.0.0.1，原因可能是因为我是虚拟机

ubuntu@ubun2004:~/work/xv6-labs-2020$ hostname -a
ubun2004
ubuntu@ubun2004:~/work/xv6-labs-2020$ hostname -i
127.0.1.1

查看 etc内的文件:

 以我的阿里云主机为例

[root@haohaoxuexi ~]# cat /etc/hosts
::1     localhost       localhost.localdomain   localhost6      localhost6.localdomain6
127.0.0.1 localhost  localhost
172.24.48.63 haohaoxuexi  haohaoxuexi
103.224.251.67 www.bt.cn



[root@haohaoxuexi etc]# cat /etc/shadow
root:$6$yqGz78F4Ij/R$QXP5xZFmg5U0P09lh4V/SWSeJrD//2CkZHhFn9jSEsw8AC7NGQyaUO8LuDfOybxHWh0Srpa0DPEdJkw/ZZGj//:18783:0:99999:7:::
bin:*:17834:0:99999:7:::
daemon:*:17834:0:99999:7:::
adm:*:17834:0:99999:7:::
lp:*:17834:0:99999:7:::
sync:*:17834:0:99999:7:::
shutdown:*:17834:0:99999:7:::
halt:*:17834:0:99999:7:::
mail:*:17834:0:99999:7:::

[root@haohaoxuexi etc]# cat /etc/networks 
default 0.0.0.0
loopback 127.0.0.0
link-local 169.254.0.0

其中/etc/networks文件为符号链接，直接连接到 /etc/inet/networks, 不过我查了自己的虚拟机和阿里云，并没有inet这个目录