How the shell generates random numbers

Method 1: Use/dev/urandom

[[email protected] shell]# tr -dc  "0-9"   < /dev/urandom | head -c 10        # Generate 10 Digital 5798734885[[email protected] shell]# [[email protected] shell]# [[email  protected] shell]# tr -dc  "A-Z"  < /dev/urandom | head -c  10         #生成10个小写字符xxcudpzyfu [[Email protected] shell ]# [[email protected] shell]# tr -dc  "A-Z"  < /dev/urandom |  head -c 10         #生成10个大写字符XFDBEFCDKV [[email  protected] shell]# [[email protected] shell]# tr -dc  "0-9,a-z"  <  /dev/urandom | head -c 10   #生成数字和字符的组合ryjhjhnpyd [[email protected]  shell]# 

Method Two: Use Date +%s

1. Randomly generate a bunch of numbers

[Email protected]:/home/dell/shell# date +%s |cksum |cut-d ""-F 1 1934689009

Expansion: Randomly generates a number within 10

[Email protected]:/home/dell/shell# echo "' Date +%s |cksum |cut-d" "-F 1 '%100" |bc81

2. Randomly generate a string of lowercase letters

[Email protected]:/home/dell/shell# Date +%s| md5sum | Tr-dc "A-Z" |head-c 10[email protected]:/home/dell/shell#

3. Randomly generated combinations of numbers and letters

[Email protected]:/home/dell/shell# Date +%s| md5sum | Head-c 1067e

Method Three: Using OpenSSL rand

[Email protected]:/home/dell/shell# OpenSSL rand-base64 40c6s7wofbx3s4imkzb9mhdkcywzyreae0lauqplpcaex+kf8hakxorw==

This article is from the "Hello World" blog, so be sure to keep this source http://237085.blog.51cto.com/227085/1959461

How the shell generates random numbers