1. date
   date +%s是獲取當前時間距離1970-01-01 00:00:00 UTC的時間差

   
   [[email protected] ~]$ date +%s
   1532874352
   
   [[email protected] ~]$ date +%s | sha256sum  | head -c 32; echo
   7811280b0dcdc3e790d0c6d2c1ab2375
   

2. $RANDOM

   [[email protected] ~]$ echo $RANDOM
   32264
   
   [[email protected] ~]$ echo $RANDOM | sha256sum | head -c 32
    
   ; echo
   1df8ddd6e3af142c9e4717508ad2e1d1
   

3. awk中的rand()函式

   
   # rand函式生成[0, 1)之間的小數
   
   [[email protected] ~]$ echo '' | awk '{print(rand())}'
   0.237788
   
   [[email protected] ~]$ awk -f randomStr.awk
   os0jKlYkEjwE4q3nNJugFJ0cgNaSgDpP

   其中randomStr.awk內容如下：

   BEGIN {
       STR_LEN=32
       print(randomStr(STR_LEN))
   }
   
   
   # gen a number in [1, n]
    
   
   
   function randomInt(n) {
       return int(n *rand()) + 1;
   }
   
   
   # gen a letter in [a-zA-Z0-9]
   
   function randomLetter() {
       # substr(str, startIndex(從1開始算), 擷取長度)
       return substr("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789", randomInt(62), 1);
   }
   
   
   # randomStr(LEN): return a random word with a length of LEN
    
   
   
   function randomStr(LEN) {
       str=""
       for(j = 1; j <= LEN; j++) {
           str = str""randomLetter()
       }
       return str
   }

4. ifconfig

   
   # ifconfig每次輸出都不太一樣，這樣也可以模擬隨機
   
   
   # 其實ps -ef也可以:)
   
   [[email protected] ~]$ ifconfig | sha256sum | head -c 32; echo
   ae59751e48893cce075a612f1e03d9dc
   
   [[email protected] ~]$ ifconfig | sha256sum | head -c 32; echo
   e320af8593e44d6d97b015fed901cc8e

5. 利用/proc/sys/kernel/random/uuid

   [[email protected] ~]$ cat /proc/sys/kernel/random/uuid | sha256sum | head -c 32; echo
   02b728b88dc810e5e2531fa4af7f70af

6. 利用shuf命令

   
   # 引數解釋
   
   
   # -z: 輸出為一行(end lines with 0 byte, not newline)
   
   
   # -e: echo輸出(treat each ARG as an input line)
   
   
   # -r: 任意字元可重複多次（output lines can be repeated）
   
   [[email protected] ~]$ shuf -zer -n32  {A..Z} {a..z} {0..9}; echo
   1IGdfCqxYkJ8MAVAW7COdwuyoSWYHr0x

歡迎補充指正！