这个 Shell 脚本初始化分区上的交换空间。签名检测的代码重复了 6 次，因为很多时候签名只有在第二次或第三次尝试时才能被正确检测到。
(改编自 H. Peter Anvin 的原始交换空间 HOWTO)
#!/bin/sh
#
# swapinit.sh - activate the swap partition
#
# written by Rahul U. Joshi
# Verify and initialize swap space
#
echo -n 'Verifying swap space... '
loopcount=0
# flag to indicate whether the partition has been activated or not
activated=0
# check for signatures 6 times before giving up
while [ $loopcount -lt 6 ]
do
if [ "`/bin/dd 2>/dev/null if=/dev/winswap bs=1 count=10 skip=4086`" = 'SWAP-SPACE' ]; then
echo "Linux signature found, iteration $loopcount"
echo "Activating swap partitions"
swapon /dev/winswap
activated=1
break
elif [ "`/bin/dd 2>/dev/null if=/dev/winswap bs=1 count=11 skip=43`" = 'SWAP SPACE ' ]; then
echo "DOS signature found, iteration $loopcount"
echo "Making swap partition"
mkswap /dev/winswap YYYYY
echo "Activating swap partitions"
swapon /dev/winswap
activated=1
break
else
let loopcount=loopcount+1
fi
done
if [ $activated -ne 1 ] ; then
echo "Swap signature not found after $loopcount tries"
echo "No swapping partitions activated"
exit 1
fi