First, according to series list Linux distributions and describe connections and differences between the different releases.
(A) major hairstyle version
1, debian: ubuntu, deepin (depth), mint and so on.
2, Slackware: SUSE Linux Enterprise Server (SLES), OpenSuse the desktop, MNIS and so on.
3, RedHat: RHEL (RedHat Eterprise Linux), CentOS, Fedora, Kylin like.
4, Other: ArchLinux, LFS, Android (kernel + busybox + java virtual machine), Gemtoo and so on.
(B) the links between different releases
1, All distributions use the Linux kernel.
2, both under the GPL GNU organization.
3, consistent with all versions of Linux distributions naming format.
(C) the difference between the different hairstyles version
1, different distributions have different versions of the Linux kernel, libraries and software.
2, a different release package manager used different (redhat slackware series and using the rpm package management system, with .rpm extension; Debian series using dpkg package management system to .deb extension).
Second, the installation Centos7.6 operating system, create a name of your own user name and login of the major steps screenshots.
1. Open VMware, click Create a new virtual machine, as shown:
2, open the New Virtual Machine wizard, select the operating system is installed later then click Next, as shown:
3. In the New wizard, select Linux guest operating system, select the version for Linux CD image, where the selection CentOS7 64, and then click Next, as shown:
4、给新建虚拟机命名并且选择合适的安装位置，然后点击下一步，如图：
5、给新建虚拟机硬盘指定大小，大小可以根据自己的需要来选择，这里选择为40G,其它默认即可，点击下一步，如图：
6、根据需要自定义硬件，这里内存选择2G，其它根据需要选择，选择完后，硬件界面向导点击关闭，然后点击完成如图：
7、安装CentOS7镜像，在新建好的虚拟机中，点击编辑此虚拟机，然后选择CD/DVD,选择使用ISO映象文件，浏览选择下载好的CentOS7的映象地址，然后点击确定，如图：
8、设置完成以后，点击开启此虚拟机，然后进入安装界面，如图：
9、鼠标点击屏幕，然后按下方向键选择第二项Test this & install centos7，并按下回车，如图：
10、安装语言选择英语，然后按下Continue进行下一步，进入如下界面，如图：
11、进行时间（选择亚洲上海）、键盘（US）设置，如图：
12、根据需要进行选择需要安装的功能，SOFTWARE1、2分别为系统来源，与系统安装功能，如图：
13、点击SYSTEM，选择手工分区，对/（根）、Swap、boot分区进行大小分区，如图：
14点击开始安装，并且设置root登录口令，新建一个用户wh，如图：
15、等待系统安装完成，用新建的用户wh登录图形界面，进入系统，如图：
三、配置环境变量，实现执行history的时候可以看到执行命令的时间。
执行该命令export HISTTIMEFORMAT="%F %T "，在当前shell执行history命令的时候会显示时间，退出则失效
To permanently take effect, you need to write to the current user's .bashrc file export HISTTIMEFORMAT = "% F% T " command, and with the source .bashrc take effect without restarting the computer. To take effect common to all users, you need to modify the profile file.
IV Summary Linux philosophy.
1, everything is a file.
2, a small, single-purpose program.
3, linker together to accomplish complex tasks.
4, to avoid confusing user interface.
5, the configuration data stored in the text.
V. Summary Linux common commands using the format and illustrated by an example. E.g. echo, screen, date, ifconfig, export commands
(a) Format
the COMMAND [OPTIONS ...] [... ARGUMENTS]
the COMMAND represents a command
OPTIONS represent options options long (e.g. --help) and short options ( as -a, -l; short options can be combined, such as -al), is used to enable or shut down one or some function commands.
ARGUMENTS shows the effect of an object (such as file name, user name, etc.) of the command parameters.
(Ii) the text after the echo output
(C) screen to create a new screen answer
screen -s helpme (create a screen session)
screen -x helpme (adding screen session)
screen -ls (currently displayed screen session)
(d) date display system time
(E) displaying the ifconfig or configure a network device (Network Interface Card) command
(Vi) export set or display environment variables.
