shell产生随机数七种方法的实现

echo $RANDOM

#!/bin/bash  
function rand(){ 
 min=$1 
 max=$(($2-$min+1)) 
 num=$(($RANDOM+1000000000)) #增加一个10位的数再求余 
 echo $(($num%$max+$min)) 
}  
rnd=$(rand 400000 500000) 
echo $rnd  
exit 0

awk 'BEGIN{srand();print rand()*1000000}' #可以加上if判断

openssl rand -base64 8 | md5sum | cut -c1-8 #八位字母和数字的组合，3a61800e
openssl rand -base64 8 | cksum | cut -c1-8  #八位数字，10784736

date +%s%N #生成19位数字，1287764807051101270
date +%s%N | cut -c6-13 #取八位数字，21793709
date +%s%N | md5sum | head -c 8 #八位字母和数字的组合，87022fda

#!/bin/bash 
 
function rand(){ 
 min=$1 
 max=$(($2-$min+1)) 
 num=$(date +%s%N) 
 echo $(($num%$max+$min)) 
}  
rnd=$(rand 1 50) 
echo $rnd  
exit 0 

cat /dev/urandom | head -n 10 | md5sum | head -c 10  #32f1e953ac
cat /dev/urandom | strings -n 8 | head -n 1  #生成全字符的随机字符串，08" " -f1 #urandom的数据很多使用cat会比较慢，在此使用head读200行，cksum将读取文件内容生成唯一的表示整型数据，cut以” “分割然后得到分割的第一个字段数据

 cat /proc/sys/kernel/random/uuid| cksum | cut -f1 -d" " #获取不同的随机整数，1675034933
 cat /proc/sys/kernel/random/uuid| md5sum | cut -c1-8 #数字加字母的随机数，d69a7ebf

#!/bin/bash 
function rand(){ 
 min=$1 
 max=$(($2-$min+1)) 
 num=$(cat /proc/sys/kernel/random/uuid | cksum | awk -F ' ' '{print $1}') 
 echo $(($num%$max+$min)) 
}  
rnd=$(rand 100 500) 
echo $rnd  
exit 0

pool=(a b c d e f g h i j k l m n o p q r s t 1 2 3 4 5 6 7 8 9 10)
num=${#pool[*]}
result=${pool[$((RANDOM%num))]}

#!/bin/bash 
length=8 
i=1 
seq=(0 1 2 3 4 5 6 7 8 9 a b c d e f g h i j k l m n o p q r s t u v w x y z A B C D E F G H I J K L M N O P Q R S T U V W X Y Z) 
num_seq=${#seq[@]} 
 
while [ "$i" -le "$length" ] 
do 
 seqrand[$i]=${seq[$((RANDOM%num_seq))]} 
 let "i=i+1" 
done 
 
echo "The random string is:" 
for j in ${seqrand[@]} 
do 
 echo -n $j 
done 
echo 

#!/bin/bash 
#RANDOM=$$ 
PIPS=6 
MAX=1000 
throw=1 
 
one=0 
two=0 
three=0 
four=0 
five=0 
six=0 
count() 
{ 
case "$1" in 
 0) let "one=one+1";; 
 1) let "two=two+1";; 
 2) let "three=three+1";; 
 3) let "four=four+1";; 
 4) let "five=five+1";; 
 5) let "six=six+1";; 
esac 
} 
 
while [ "$throw" -le "$MAX" ] 
do 
 let "dice=RANDOM % $PIPS" 
 count $dice 
 let "throw=throw+1" 
done 
 
echo "The statistics results are as follows:" 
echo "one=$one" 
echo "two=$two" 
echo "three=$three" 
echo "four=$four" 
echo "five=$five" 
echo "six=$six" 

#!/bin/bash 
#批量创建10个系统帐号并设置密码，帐号和密码相同 
for name in `seq -w 10` 
do 
 #非交互式的输入密码 
 useradd linux$name && echo "linux$name" | passwd --stdin linux$name 
done 

#!/bin/bash 
#批量创建10个系统帐号并设置密码 
rm -f user.log 
for name in `seq -w 10` 
do 
 #非交互式的输入随机密码 
 password=`echo $RANDOM | md5sum | cut -c1-8` 
 #可以使用password=`echo "date $RANDOM" | md5sum | cut -c3-11` 
 #也可以使用password=`penssl rand -base64 8 | md5sum | cut -c1-8` 
 useradd linux$name && echo password | passwd --stdin linux$name 
 echo -e "user=linux$name \t passwd=$password"  user.log #保存用户名密码以查阅 
done