bash中的均匀随机正十进制数 [英] Uniform random positive decimal number in bash

问题描述

我想使用ping进行随机的ICMP通信.我需要在代码中为时间参数设置一个介于0.5到1之间的随机十进制数.您能告诉我如何制作统一的随机十进制数吗?我的代码只能使一个整数.谢谢

I would like to make a random ICMP traffic using ping. I need to make a random decimal number between 0.5 to 1 for time parameter in my code. Could you please show me how to make uniform random decimal number? My code just can make a integer number. Thanks

#!/bin/bash

for ((i = 0; i <=100; i++))
do
#need to have random number between 0.5 to 1 for time
time=$(($RANDOM%5+1))
num=$(($RANDOM%5+1)) 

ping -c $num -i $time 10.0.0.2 

done

推荐答案

bash 实际上不是做十进制数，只能是整数，但是您可以通过生成来伪造十进制数整数并将小数点放在开头.

bash doesn't actually do decimal number, only integers, but you can fake decimals by generating integers and putting a decimal point at the start.

尝试一下:

echo "0.$(( ($RANDOM%500) + 500))"

关于均匀性，您可以生成10,000个这样的样本:

As regards it being uniform, you can generate 10,000 samples like this:

for ((i=1;i<10000;i++)) ; do echo "0.$(( ($RANDOM%500) + 500))" ; done > data

然后使用 gnuplot 绘制频率分布，如下所示:

And then plot the frequency distribution with gnuplot like this:

gnuplot --persist <<EOF

# Make some suitable labels.
set title "Number Distribution"
set xlabel "Value"
set ylabel "Count"

set style histogram clustered gap 1
set style fill solid border -1

binwidth=0.01
set boxwidth binwidth
bin(x,width)=width*floor(x/width) + binwidth/2.0

plot 'data' using (bin(\$1,binwidth)):(1.0) smooth freq with boxes
EOF

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