for num in `echo ${ip_addr} | sed "s/./ /g"`是什么意思

这段代码是一个 shell 脚本的 for 循环语句，其中 `${ip_addr}` 是一个变量，代表一个 IP 地址。这个循环的目的是将 IP 地址中的每个数字（由点号分隔）分别取出来，存入变量 `num` 中，以便进行后续的处理。具体来说，这里使用了 `sed` 命令将 IP 地址中的每个字符都替换成了一个空格，然后通过循环语句遍历这些空格分隔的数字。

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start_addr=0x05877000 #end_addr=0x3ffff000 end_addr=0x05877002 data_write=0x55AA55AA data_read=$(printf "%08x" $data_write) count=0 match_count=0 for ((addr=$start_addr; addr<$end_addr; addr=addr+4)); do echo $data_write | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/nul data=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"') #percent=$(echo "scale=2; ($addr - $start_addr) * 100 / ($end_addr - $start_addr)" | bc) # echo -ne "Writing: $percent%\r" done # echo $data for ((addr=$start_addr; addr<$end_addr; addr+=4)); do data=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"') if [ "$data_write" == "$data_read" ]; then match_count=$((match_count+1)) fi count=$((count+1)) # percent=$(echo "scale=2; $count * 100 / (($end_addr - $start_addr) / 4)" | bc) # echo -ne "Reading: $percent%\r" done #echo $data echo $data_read echo $data_write 如果data_read=55aa55aa，data_write=0x55AA55AA,那么该如何修改程序才能让程序输出PASS

为了让程序输出PASS，我们需要在读取数据的循环中加入判断，当读取到的数据与写入的数据相同时，match_count 加 1。然后在循环结束后，判断 match_count 是否等于 count，如果等于，即所有数据都成功写入并且读取正确，就输出 PASS。

修改后的代码如下：

start_addr=0x05877000
end_addr=0x3ffff000
data_write=0x55AA55AA
data_read=$(printf "%08x" $data_write)
count=0
match_count=0

for ((addr=$start_addr; addr<$end_addr; addr=addr+4)); do
    echo $data_write | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/nul
    #percent=$(echo "scale=2; ($addr - $start_addr) * 100 / ($end_addr - $start_addr)" | bc)
    #echo -ne "Writing: $percent%\r"
done

for ((addr=$start_addr; addr<$end_addr; addr+=4)); do
    data=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"')
    if [ "$data_write" == "$data" ]; then
        match_count=$((match_count+1))
    fi
    count=$((count+1))
    #percent=$(echo "scale=2; $count * 100 / (($end_addr - $start_addr) / 4)" | bc)
    #echo -ne "Reading: $percent%\r"
done

if [ $match_count -eq $count ]; then
    echo "PASS"
else
    echo "FAIL"
fi

#echo $data
echo $data_read
echo $data_write

这样，当数据写入并读取成功时，程序就会输出 PASS。

start_addr=0x05877000 #end_addr=0x3ffff000 end_addr=0x05877002 data_write=0x55AA55AA data_read=$(printf "%08x" $data_write) count=0 match_count=0 for ((addr=$start_addr; addr<$end_addr; addr=addr+4)); do echo $data_write | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/nul done for ((addr=$start_addr; addr<$end_addr; addr+=4)); do data=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"') if [ "$data_read" == "$data" ]; then match_count=$((match_count+1)) fi count=$((count+1)) done echo $data echo $data_read那么该如何修改程序才能让程序输出PASS

为了让程序输出 PASS，我们需要在循环结束后，判断 match_count 是否等于 count，如果等于，即所有数据都成功读取并且与写入的数据一致，就输出 PASS。

修改后的代码如下：

start_addr=0x05877000
end_addr=0x3ffff000
data_write=0x55AA55AA
data_read=$(printf "%08x" $data_write)
count=0
match_count=0

for ((addr=$start_addr; addr<$end_addr; addr=addr+4)); do
    echo $data_write | dd of=/dev/mem bs=4 count=1 seek=$(($addr/8)) conv=notrunc 2>/dev/nul
done

for ((addr=$start_addr; addr<$end_addr; addr+=4)); do
    data=$(dd if=/dev/mem bs=4 count=1 skip=$(($addr/4)) 2>/dev/null | hexdump -e '/4 "%08x\n"')
    if [ "$data_read" == "$data" ]; then
        match_count=$((match_count+1))
    fi
    count=$((count+1))
done

if [ $match_count -eq $count ]; then
    echo "PASS"
else
    echo "FAIL"
fi

echo $data
echo $data_read

这样，当所有数据都成功读取并且与写入的数据一致时，程序就会输出 PASS。