backtrack arm启动脚本解析

启动脚本http://forum.xda-developers.com/showthread.php?t=1094237

perm=$(id|cut -b 5)

if [ "$perm" != "0" ];then echo "This Script Needs Root! Type : su";exit;fi

mount -o remount,rw /dev/block/mmcblk0p5 /system
export kit=/sdcard/BT5
export bin=/system/bin
export mnt=/data/local/mnt
export stor=$mnt/root/storage
export sdcard=$stor/sdcard
export extsd=$stor/external_sd
export usb=$stor/usb_storage
mkdir -p $mnt
export PATH=$bin:/usr/bin:/usr/local/bin:/usr/sbin:/bin:/usr/local/sbin:/usr/games:$PATH
export TERM=linux
export HOME=/root
export USER=root
if [ -b /dev/loop2 ]; then
	echo "Loop device exists"
else
	busybox mknod /dev/loop2 b 7 0   

#BusyBox 是一个集成了一百多个最常用linux命令和工具的软件

#mknod 命令的第一种形式只能由 root 用户或系统组成员执行。在第一种形式中，使用了b 或 c 标志。b 标志表示这个特殊文件是面向块的设备（磁盘、软盘或磁带）
fi
mount -o loop,rw,noatime -t ext2 $kit/bt5.img $mnt   

#-o loop：option用来把一个文件当成硬盘分区挂接上系统 可读可写
echo "mounting storage devices in $stor..." 
mkdir -p $sdcard
mkdir -p $extsd
mkdir -p $usb
busybox mount --bind /mnt/sdcard $sdcard  

#在手机的shell中可以看见 sdcard已经被安卓 加载在/mnt里面  这里是把sdcard再映射到bt里面去
busybox mount --bind /mnt/external_sd $extsd
busybox mount --bind /mnt/usb_storage $usb
mount -t devpts devpts $mnt/dev/pts
mount -t proc proc $mnt/proc
mount -t sysfs sysfs $mnt/sys
busybox sysctl -w net.ipv4.ip_forward=1
echo "nameserver 8.8.8.8" > $mnt/etc/resolv.conf
echo "127.0.0.1 localhost bt5" > $mnt/etc/hosts
busybox chroot $mnt /bin/bash

echo "Shutting down BackTrack ARM for Iconia A500"
umount $sdcard
umount $extsd
umount $usb
umount $mnt/dev/pts
umount $mnt/proc 
umount $mnt/sys 
umount $mnt