The shell generates a specified range of random numbers with random strings.

Shell generates a specified range of random numbers and random stringsCategory: Shell 2014-04-22 22:17 20902 People read Comments (5) favorite reports Shellrandomurandomuuidlinux

Shell generates a specified range of random numbers and random strings

1. Using the $RANDOM variables of the system

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1. [Email protected]:~$ Echo $RANDOM
2. 17617

[Email protected]:~$ echo $RANDOM 17617

the range of $RANDOM is [0, 32767]

If you need to generate more than 32767 random numbers, you can do so in the following ways.

Example: Generating a random number of 400000~500000

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1. #!/bin/bash
3. function rand () {
4. Min=$1
5. max=$ (($2-$min + 1))
6. num=$ (($RANDOM +1000000000)) #增加一个10位的数再求余
7. echo $ (($num% $max + $min))
8. }
10. rnd=$ (Rand 400000 500000)
11. Echo $rnd
13. Exit 0

#!/bin/bashfunction 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 $rndexit 0

2. Using the date +%s%n

Example: Generating a random number of 1~50

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1. #!/bin/bash
3. function rand () {
4. Min=$1
5. max=$ (($2-$min + 1))
6. num=$ (Date +%s%n)
7. echo $ (($num% $max + $min))
8. }
10. rnd=$ (Rand 1 50)
11. Echo $rnd
13. Exit 0

#!/bin/bashfunction rand () {    min=$1    max=$ (($2-$min + 1))    num=$ (date +%s%n)    echo $ (($num% $max + $min))} rnd=$ (Rand 1) echo $rndexit 0

3. Using/dev/random and/dev/urandom

The/dev/random stores the real-time data of the current operating environment of the system, which is a random number generator that is blocked and sometimes needs to wait for reading.

/dev/urandom non-blocking random number generator, the read operation does not cause blocking.

Example: Using/dev/urandom to generate 100~500 random numbers, use urandom to avoid blocking.

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1. #!/BIN/BASH  
2.   
3. function rand () {   
4.     min=$1  
5.      max=$ (($2-$min + 1))   
6.     num=$ (cat /dev/urandom | head  -n 10 | cksum | awk -F  '   '   ' {print $1} '   
7.     echo $ (($num% $max + $min))   
8. }  
9.   
10. rnd=$ (rand 100 500)   
11. echo   $rnd   
12.   
13. EXIT 0  

#!/bin/bashfunction rand () {    min=$1    max=$ (($2-$min + 1))    num=$ (cat/dev/urandom | head-n | cksum | awk-f " ' {print $} ')    echo $ (($num% $max + $min))}rnd=$ (rand) echo $rndexit 0

4. Using the Linux UUID

The UUID full name is a universal unique identifier, formatted with 32 16 binary digits, with a '-' connection number divided into 5 segments. The form is 32 characters of 8-4-4-4-12.

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1. [Email protected]:~/shell$ cat/proc/sys/kernel/random/uuid
2. Fd496199-372a-403e-8ec9-bf4c52cbd9cd

[Email protected]:~/shell$ CAT/PROC/SYS/KERNEL/RANDOM/UUIDFD496199-372A-403E-8EC9-BF4C52CBD9CD

Example: generating 100~500 random numbers using Linux uuid

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1. #!/BIN/BASH  
2.   
3. function rand () {   
4.     min=$1  
5.      max=$ (($2-$min + 1))   
6.     num=$ (cat /proc/sys/kernel/random/uuid  | cksum | awk -F  '   '   ' {print $1} '   
7.     echo $ (($num% $max + $min))   
8. }  
9.   
10. rnd=$ (rand 100 500)   
11. echo  $rnd   
12.   
13. EXIT 0  

#!/bin/bashfunction rand () {    min=$1    max=$ (($2-$min + 1))    num=$ (Cat/proc/sys/kernel/random/uuid | cksum | Awk-f "{print $} ')    echo $ (($num% $max + $min))}rnd=$ (rand) echo $rndexit 0

5. Generating random strings

Example: Generating a 10-bit random string

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1. #使用date Generate random strings
2. Date +%s%n | md5sum | Head-c 10
4. #使用/dev/urandom Generate random strings
5. Cat/dev/urandom | Head-n 10 | md5sum | Head-c 10

The shell generates a specified range of random numbers with random strings.