我们正在将几个系统从 Debian Lenny 升级到 Squeeze,我想确保我没有错过任何 grub2 安装。默认情况下,Squeeze 从 grub1 链式引导加载,您必须运行upgrade-from-grub-legacy
才能升级。因此,我希望能够远程检查 grub2 是否已安装在磁盘引导扇区中,而无需重新启动,也不会覆盖引导扇区。
有什么比对硬盘早期块进行十六进制转储并尝试识别 grub2 特定的字节更简单的方法吗?
答案1
我在 grub2 debian 源代码包中偶然发现了答案。事实证明,它确实需要转储引导扇区 - 因此单独打包的脚本可能会有用。这是一个脚本(只是官方函数的包装器),它将告诉您 grub2 是否已安装到引导扇区中。它可以轻松修改以用于类似用途。
#!/bin/bash
set -e
if [ "$UID" -ne "0" ]; then
echo Must be run as root
exit 99
fi
scan_grub2()
{
if ! dd if="$1" bs=512 count=1 2>/dev/null | grep -aq GRUB; then
# No version of GRUB is installed.
echo Grub could not be found
return 1
fi
# The GRUB boot sector always starts with a JMP instruction.
initial_jmp="$(dd if="$1" bs=2 count=1 2>/dev/null | od -Ax -tx1 | \
head -n1 | cut -d' ' -f2,3)"
[ "$initial_jmp" ] || return 1
initial_jmp_opcode="${initial_jmp%% *}"
[ "$initial_jmp_opcode" = eb ] || return 1
initial_jmp_operand="${initial_jmp#* }"
case $initial_jmp_operand in
47|4b|4c|63)
# I believe this covers all versions of GRUB 2 up to the package
# version where we gained a more explicit mechanism. GRUB Legacy
# always had 48 here.
return 0
;;
esac
return 1
}
if scan_grub2 "/dev/sda"; then
echo Found grub 2
else
echo Did not find grub 2
#Uncomment the next line to upgrade
#upgrade-from-grub-legacy
fi