正常操作：
1 添加共享文件夹
设置-》共享文件夹-》添加共享路径。
2 linux 内部挂载共享目录
mount -t vboxsf 共享文件名称 /mnt/文件夹名称
mount -v vboxsf software /mnt/hsoft
3 设置开机启动
添加执行权限： chmod +X etc/rc.d/rc.local x是大写
编辑： vi /etc/rc.local 或者 vi /etc/rc.d/rc.local
mount -t vboxsf software /mnt/hsoft
指定挂载目录的用户组：
如果挂载时候需要指定目录权限，先获取用户组ID
如www -》 id www
uid=1000(www) gid=1000(www) groups=1000(www)
挂载目录是www用户组
mount -t vboxsf -o uid=1000,gid=1000,umask=022 software /mnt/hsoft
df -h 查看磁盘情况，验证磁盘是否加入成功，目录共享成功
https://www.kancloud.cn/ichenpeng/blog/1134174
常见问题：
1 挂载失败 -unknown filesystem type vboxsf
mount -t vboxsf software /mnt/hsoft
提示：-unknown filesystem type vboxsf
解决：安装虚拟增强。设备-》安装增强功能。
或者设置存储，设置光盘选择VBoxGuestAdditions.ios（在安装目录）。没有可以去官网下载
安装成功以后一般在 /media/GuestAdditionsISO 有VBoxLinuxAdditions.run文件。
执行：
./VBoxLinuxAdditions.run
然后挂载
mount -t vboxsf software /mnt/hsoft
2 增强时候报错
./VBoxLinuxAdditions.run Verifying archive integrity... All good. Uncompressing VirtualBox 5.2.16 Guest Additions for Linux........ VirtualBox Guest Additions installer Copying additional installer modules ... Installing additional modules ... VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel modul es. This may take a while. This system is currently not set up to build kernel modules. Please install the gcc make perl packages from your distribution. VirtualBox Guest Additions: Starting. VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel modul es. This may take a while. This system is currently not set up to build kernel modules. Please install the gcc make perl packages from your distribution.
解决：
yum -y install build-essential gcc make perl
3 增强以后 /media/目录下无 /GuestAdditionsISO/VBoxLinuxAdditions.run
find / -name VBoxLinuxAdditions.run 不存在文件
第一种方式：
存储 添加光驱 VBoxGuestAdditions.iso，centos 挂载。
yum update kernel -y yum install kernel-devel kernel-headers -y yum install the gcc make perl -y uname -r reboot uname -r iso文件挂载到自己的系统中,lsblk 查看下设备号. lsblk mkdir /mnt/cdrom mount /dev/sr0 /mnt/cdrom cd /mnt/cdrom ./VBoxLinuxAdditions.run vi /etc/rc.d/rc.local mount /dev/sr0 /mnt/cdrom
查看挂载
df -h
第二种方式：下载导入VBoxGuestAdditions.iso文件。根据virtualbox版本下载。比如我的virtualbox是5.2.16
下载目录：http://download.virtualbox.org/virtualbox/5.2.16/
http://download.virtualbox.org/virtualbox/5.2.16/VBoxGuestAdditions_5.2.16.iso
wget 下载 wget http://download.virtualbox.org/virtualbox/5.2.16/VBoxGuestAdditions_5.2.16.iso [root@localhost home]# ls ftpuser VBoxGuestAdditions_5.2.16.iso mount -o loop /home/VBoxGuestAdditions_5.2.16.iso /media/GuestAdditionsISO cd /media/GuestAdditionsISO ls -l ./VBoxLinuxAdditions.run
参考：
https://askubuntu.com/questions/321589/unable-to-mount-the-cd-dvd-image-on-the-machine-sandbox