1.make help查看当前平台的编译帮助信息。make ARCH=arm help查看指定平台的编译帮助信息。make help | grep -i "cleaning targets" -A4查看三种清除编译信息的方式。
[root@lab1 linux]# make help
[root@lab1 linux]# make ARCH=arm help
[root@lab1 linux]# make help | grep -i "cleaning targets" -A4
Cleaning targets:
clean - Remove most generated files but keep the config and
enough build support to build external modules
mrproper - Remove all generated files + config + various backup files
distclean - mrproper + remove editor backup and patch files
2.screen开启一个屏幕（ctrl+a,d退出）。screen开启一个屏幕，ls /etc在开启的屏幕进行操作（ctrl+a,d退出）。screen -ls查看打开的屏幕情况。screen -r 12271恢复进入屏幕。screen -ls | tail -n2可以看到每次会在/var/run/screen/S-root生成套接字进程（不同于终端界面关闭后操作会停止，screen不受终端界面关闭的影响）。
[root@lab1 linux]# screen
[detached from 12258.pts-0.lab1]
[root@lab1 linux]# ls /etc
[root@lab1 linux]# screen
[detached from 12271.pts-0.lab1]
[root@lab1 linux]# screen -ls
There are screens on:
12271.pts-0.lab1 (Detached)
12258.pts-0.lab1 (Detached)
2 Sockets in /var/run/screen/S-root.
[root@lab1 linux]# screen -r 12271
[root@lab1 linux]# screen -ls | tail -n2
2 Sockets in /var/run/screen/S-root.
3.mkdir /media/cdrom创建挂载目录。mount -r /dev/cdrom /media/cdrom进行挂载。 ll查看文件目录信息。ll isolinux/ | grep initrd其中有启动程序。ll isolinux/ | grep vmlinuz还有内核程序。ll isolinux/ | grep isolinux还有引导程序第二部分及其配置信息。ll isolinux/ | grep boot.cat引导程序第一部分。
[root@lab1 linux]# mkdir /media/cdrom
[root@lab1 linux]# mount -r /dev/cdrom /media/cdrom
[root@lab1 linux]# cd /media/cdrom
[root@lab1 cdrom]# ll
total 664
-rw-rw-r--. 3 root root 14 Sep 5 2017 CentOS_BuildTag
drwxr-xr-x. 3 root root 2048 Sep 5 2017 EFI
-rw-rw-r--. 3 root root 227 Aug 30 2017 EULA
-rw-rw-r--. 3 root root 18009 Dec 9 2015 GPL
drwxr-xr-x. 3 root root 2048 Sep 5 2017 images
drwxr-xr-x. 2 root root 2048 Sep 5 2017 isolinux
drwxr-xr-x. 2 root root 2048 Sep 5 2017 LiveOS
drwxrwxr-x. 2 root root 641024 Sep 4 2017 Packages
drwxr-xr-x. 2 root root 4096 Sep 5 2017 repodata
-rw-rw-r--. 3 root root 1690 Dec 9 2015 RPM-GPG-KEY-CentOS-7
-rw-rw-r--. 3 root root 1690 Dec 9 2015 RPM-GPG-KEY-CentOS-Testing-7
-r--r--r--. 1 root root 2883 Sep 6 2017 TRANS.TBL
[root@lab1 cdrom]# ll isolinux/ | grep initrd
-rw-r--r--. 1 root root 48434768 Sep 5 2017 initrd.img
[root@lab1 cdrom]# ll isolinux/ | grep vmlinuz
-rwxr-xr-x. 1 root root 5877760 Aug 22 2017 vmlinuz
[root@lab1 cdrom]# ll isolinux/ | grep isolinux
-rw-r--r--. 1 root root 24576 Sep 5 2017 isolinux.bin
-rw-r--r--. 1 root root 3032 Sep 5 2017 isolinux.cfg
[root@lab1 cdrom]# ll isolinux/ | grep boot.cat
-r--r--r--. 1 root root 2048 Sep 6 2017 boot.cat
4.cat isolinux/isolinux.cfg | grep "menu label"查看启动时显示的菜单项。cat isolinux/isolinux.cfg | grep ^label这里显示是启动时可使用的标签项（即开机ESC键进入boot界面后，输入label值将进入label对应的选项）。
[root@lab1 cdrom]# cat isolinux/isolinux.cfg | grep "menu label"
menu label ^Install CentOS 7
menu label Test this ^media & install CentOS 7
menu label Install CentOS 7 in ^basic graphics mode
menu label ^Rescue a CentOS system
menu label Run a ^memory test
menu label Boot from ^local drive
menu label Return to ^main menu
[root@lab1 cdrom]# cat isolinux/isolinux.cfg | grep ^label
label linux
label check
label vesa
label rescue
label memtest
label local
label returntomain