blocks|key|1277844|text|使用$RANDOM。与简单的shell算法结合使用时，它通常很有用。例如，生成一个介于1和10+(含)之间的随机数：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1277845|$+echo+$((1+%2B+$RANDOM+%25+10))
3|code-block|syntax|javascript|1277846|实际的生成器位于函数brand()的variables.c中。Older+versions是一个简单的线性生成器。bash的4.0版本使用了1985年论文的generator+with+a+citation，这可能意味着它是一个不错的伪随机数来源。我不会将它用于模拟(当然也不会用于加密)，但它可能足以完成基本的脚本任务。|1277847|如果你正在做一些需要严重随机数的事情，你可以使用/dev/random或/dev/urandom，如果它们可用：|1277848|$+dd+if=/dev/urandom+count=4+bs=1+%7C+od+-t+d|1277849|entityMap|0|LINK|mutability|MUTABLE|url|http://tldp.org/LDP/abs/html/randomvar.html|1|https://www.codeblog.org/viewsrc/bash-3.1/variables.c|2|http://www.bashcookbook.com/bashinfo/source/bash-4.0/variables.c^0|2|7|2|7|0|0|0|A|7|I|B|1L|4|V|E|1|26|P|2|0|O|B|10|C|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@$9|15|A|16|1|17]]|E|$]]|$1|F|3|G|5|H|7|18|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]]|D|@$9|1G|A|1H|1|1I]|$9|1J|A|1K|1|1L]]|E|$]]|$1|M|3|N|5|6|7|1M|8|@$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]]|D|@]|E|$]]|$1|O|3|P|5|H|7|1R|8|@]|D|@]|E|$I|J]]|$1|Q|3|-4|5|6|7|1S|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]|Y|$5|T|U|V|E|$W|Z]]|10|$5|T|U|V|E|$W|11]]]]

Use <a href="http://tldp.org/LDP/abs/html/randomvar.html" rel="noreferrer"><code>$RANDOM</code></a>. It's often useful in combination with simple shell arithmetic. For instance, to generate a random number between 1 and 10 (inclusive):
<pre><code>$ echo $((1 + $RANDOM % 10))
3
</code></pre>
The actual generator is in <code>variables.c</code>, the function <code>brand()</code>. <a href="https://www.codeblog.org/viewsrc/bash-3.1/variables.c" rel="noreferrer">Older versions</a> were a simple linear generator. Version 4.0 of <code>bash</code> uses a <a href="http://www.bashcookbook.com/bashinfo/source/bash-4.0/variables.c" rel="noreferrer">generator with a citation</a> to a 1985 paper, which presumably means it's a decent source of pseudorandom numbers. I wouldn't use it for a simulation (and certainly not for crypto), but it's probably adequate for basic scripting tasks.
If you're doing something that requires serious random numbers you can use <code>/dev/random</code> or <code>/dev/urandom</code> if they're available:
<pre><code>$ dd if=/dev/urandom count=4 bs=1 | od -t d
</code></pre>

blocks|key|1277991|text|您也可以使用shuf+(在coreutils中提供)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1277992|shuf+-i+1-100000+-n+1|code-block|syntax|javascript|1277993|entityMap|0|LINK|mutability|MUTABLE|url|https://man7.org/linux/man-pages/man1/shuf.1.html^0|6|4|6|4|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

You can also use <a href="https://man7.org/linux/man-pages/man1/shuf.1.html" rel="noreferrer"><code>shuf</code></a> (available in coreutils).
<pre><code>shuf -i 1-100000 -n 1
</code></pre>

blocks|key|1492706|text|在您的shell中尝试以下内容：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492707|$+od+-A+n+-t+d+-N+1+/dev/urandom|code-block|syntax|javascript|1492708|在这里，-t+d指定输出格式应该是有符号十进制；-N+1表示从/dev/urandom读取一个字节。|offset|length|style|CODE|1492709|entityMap^0|0|0|4|4|O|4|V|C|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]|$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|N|$]]

Try this from your shell:

<pre><code>$ od -A n -t d -N 1 /dev/urandom
</code></pre>

Here, <code>-t d</code> specifies that the output format should be signed decimal; <code>-N 1</code> says to read one byte from <code>/dev/urandom</code>.

blocks|key|1492679|text|你也可以从awk获取随机数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492680|awk+'BEGIN+{
+++#+seed
+++srand()
+++for+(i=1;i<=1000;i%2B%2B){
+++++print+int(1+%2B+rand()+*+100)
+++}
}'|code-block|syntax|javascript|1492681|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

you can also get random number from awk

<pre><code>awk 'BEGIN {
 # seed
 srand()
 for (i=1;i&lt;=1000;i++){
 print int(1 + rand() * 100)
 }
}'
</code></pre>

blocks|key|1492508|text|这就是$RANDOM。我不知道它到底是怎么工作的。但它是有效的。对于测试，您可以执行以下操作：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492509|echo+$RANDOM|code-block|syntax|javascript|1492510|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

There is $RANDOM.
I don't know exactly how it works. But it works.
For testing, you can do :

<pre><code>echo $RANDOM
</code></pre>

blocks|key|1278010|text|我喜欢这个技巧：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1278011|echo+${RANDOM:0:1}+#+random+number+between+1+and+9
echo+${RANDOM:0:2}+#+random+number+between+1+and+99|code-block|syntax|javascript|1278012|..。|1278013|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I like this trick:

<pre><code>echo ${RANDOM:0:1} # random number between 1 and 9
echo ${RANDOM:0:2} # random number between 1 and 99
</code></pre>

...

blocks|key|1492767|text|介于0和9之间(包括0和9)的随机数。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492768|echo+$((RANDOM%2510))|code-block|syntax|javascript|1492769|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Random number between 0 and 9 inclusive.

<pre><code>echo $((RANDOM%10))
</code></pre>

blocks|key|1277757|text|如果您使用的是linux系统，您可以从/dev/random+or+/dev/urandom获得一个随机数。如果没有足够的随机数可用，请注意/dev/random将会阻塞。如果您需要超越随机性的速度，请使用/dev/urandom。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1277758|这些“文件”将由操作系统生成的随机数填充。这取决于您的系统上/dev/random的实现是真还是伪随机数。真正的随机数是在从鼠标、硬盘、网络等设备驱动程序收集的噪声的帮助下生成的。|1277759|您可以使用dd从文件中获取随机数|1277760|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki//dev/random|1|http://en.wikipedia.org/wiki/Dd_%2528Unix%2529^0|J|E|0|0|0|5|2|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]]|C|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|H|3|-4|5|6|7|10|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]|P|$5|K|L|M|C|$N|Q]]]]

If you are using a linux system you can get a random number out of <a href="http://en.wikipedia.org/wiki//dev/random" rel="nofollow noreferrer">/dev/random or</a> /dev/urandom. Be carefull /dev/random will block if there are not enough random numbers available. If you need speed over randomness use /dev/urandom. 

These "files" will be filled with random numbers generated by the operating system. It depends on the implementation of /dev/random on your system if you get true or pseudo random numbers. True random numbers are generated with help form noise gathered from device drivers like mouse, hard drive, network. 

You can get random numbers from the file with <a href="http://en.wikipedia.org/wiki/Dd_%28Unix%29" rel="nofollow noreferrer">dd</a>

blocks|key|1492747|text|生成0到n(16位有符号整数)范围内的随机数。$RAND变量中的结果集。例如：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492748|#!/bin/bash

random()
{
++++local+range=${1:-1}

++++RAND=`od+-t+uI+-N+4+/dev/urandom+%7C+awk+'{print+$2}'`
++++let+"RAND=$RAND%25($range%2B1)"
}

n=10
while+[+$((+n+-=1+))+-ge+"0"+];+do
++++random+500
++++echo+"$RAND"
done|code-block|syntax|javascript|1492749|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Generate random number in the range of 0 to n (signed 16-bit integer). Result set in $RAND variable. For example:

<pre><code>#!/bin/bash

random()
{
 local range=${1:-1}

 RAND=`od -t uI -N 4 /dev/urandom | awk '{print $2}'`
 let "RAND=$RAND%($range+1)"
}

n=10
while [ $(( n -=1 )) -ge "0" ]; do
 random 500
 echo "$RAND"
done
</code></pre>

blocks|key|1492775|text|下面是什么：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492776|perl+-e+'print+int+rand+10,+"\n";+'|code-block|syntax|javascript|1492777|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

What about:

<pre><code>perl -e 'print int rand 10, "\n"; '
</code></pre>

blocks|key|1492844|text|程序的随机分支或yes/no；1/0；true/false输出：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1492845|if+[+$RANDOM+-gt+16383++];+then++++++++++++++#+16383+=+32767/2+
++++echo+var=true/1/yes/go_hither
else+
++++echo+var=false/0/no/go_thither
fi|code-block|syntax|javascript|1492846|如果你懒于记住16383：|1492847|if+((+RANDOM+%25+2+));+then+
++++echo+"yes"
else+
++++echo+"no"
fi|1492848|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Random branching of a program or yes/no; 1/0; true/false output:

<pre><code>if [ $RANDOM -gt 16383 ]; then # 16383 = 32767/2 
 echo var=true/1/yes/go_hither
else 
 echo var=false/0/no/go_thither
fi
</code></pre>

of if you lazy to remember 16383:

<pre><code>if (( RANDOM % 2 )); then 
 echo "yes"
else 
 echo "no"
fi
</code></pre>

blocks|key|1278080|text|一个bash函数，它使用perl生成一个n位的随机数。指定位数或模板为n+0。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1278081|rand()+{
++perl+-E+'$ARGV[0]%7C%7C="";+$ARGV[0]=int($ARGV[0])%7C%7Clength($ARGV[0]);+say+join+"",+int(rand(9)%2B1)*($ARGV[0]?1:0),+map+{+int(rand(10))+}+(0..($ARGV[0]%7C%7C0)-2)'+$1
}|code-block|syntax|javascript|1278082|用法：|1278083|$+rand+3
381
$+rand+000
728|1278084|调用随机数n的演示，n在0到15之间：|1278085|$+for+n+in+{0..15};+do+printf+"%2502d:+%25s\n"+$n+$(rand+$n);+done
00:+0
01:+3
02:+98
03:+139
04:+1712
05:+49296
06:+426697
07:+2431421
08:+82727795
09:+445682186
10:+6368501779
11:+51029574113
12:+602518591108
13:+5839716875073
14:+87572173490132
15:+546889624135868|1278086|调用rand+n的演示，对于n，长度为0到15之间的0的模板|1278087|$+for+n+in+{0..15};+do+printf+"%2515s+:%2502d:+%25s\n"+$(printf+"%250${n}d"+0)+$n+$(rand+$(printf+"%250${n}d"+0));+done
++++++++++++++0+:00:+0
++++++++++++++0+:01:+0
+++++++++++++00+:02:+70
++++++++++++000+:03:+201
+++++++++++0000+:04:+9751
++++++++++00000+:05:+62237
+++++++++000000+:06:+262860
++++++++0000000+:07:+1365194
+++++++00000000+:08:+83953419
++++++000000000+:09:+838521776
+++++0000000000+:10:+2355011586
++++00000000000+:11:+95040136057
+++000000000000+:12:+511889225898
++0000000000000+:13:+7441263049018
+00000000000000+:14:+11895209107156
000000000000000+:15:+863219624761093|1278088|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

A bash function that uses perl to generate a random number of n digits. Specify either the number of digits or a template of n 0s.
<pre><code>rand() {
 perl -E '$ARGV[0]||=&quot;&quot;; $ARGV[0]=int($ARGV[0])||length($ARGV[0]); say join &quot;&quot;, int(rand(9)+1)*($ARGV[0]?1:0), map { int(rand(10)) } (0..($ARGV[0]||0)-2)' $1
}
</code></pre>
Usage:
<pre><code>$ rand 3
381
$ rand 000
728
</code></pre>
Demonstration of calling rand n, for n between 0 and 15:
<pre><code>$ for n in {0..15}; do printf &quot;%02d: %s\n&quot; $n $(rand $n); done
00: 0
01: 3
02: 98
03: 139
04: 1712
05: 49296
06: 426697
07: 2431421
08: 82727795
09: 445682186
10: 6368501779
11: 51029574113
12: 602518591108
13: 5839716875073
14: 87572173490132
15: 546889624135868
</code></pre>
Demonstration of calling rand n, for n a template of 0s between length 0 and 15
<pre><code>$ for n in {0..15}; do printf &quot;%15s :%02d: %s\n&quot; $(printf &quot;%0${n}d&quot; 0) $n $(rand $(printf &quot;%0${n}d&quot; 0)); done
 0 :00: 0
 0 :01: 0
 00 :02: 70
 000 :03: 201
 0000 :04: 9751
 00000 :05: 62237
 000000 :06: 262860
 0000000 :07: 1365194
 00000000 :08: 83953419
 000000000 :09: 838521776
 0000000000 :10: 2355011586
 00000000000 :11: 95040136057
 000000000000 :12: 511889225898
 0000000000000 :13: 7441263049018
 00000000000000 :14: 11895209107156
000000000000000 :15: 863219624761093
</code></pre>

blocks|key|1278093|text|您可以使用种子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1278094|RANDOM=$(date+%2B%25s%25N+%7C+cut+-b10-19)
echo+$((+$RANDOM+%25+100+%2B+1+))|code-block|syntax|javascript|1278095|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can use a seed:
<pre><code>RANDOM=$(date +%s%N | cut -b10-19)
echo $(( $RANDOM % 100 + 1 ))
</code></pre>

问如何在Bash中生成随机数？
EN

回答 13

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问如何在Bash中生成随机数？EN

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问如何在Bash中生成随机数？
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