Generating a Random String of 'n' length


 
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# 1  
Old 11-03-2015
Generating a Random String of 'n' length

Hi,

How can I generate a string of random characters (alpha+numeric) of a particular length ?

For e.g. for
n=5, output = 'kasjf'
n=10, output = 'hedbcd902k'

Also, please let me know if random (valid) dates could also be generated.

Thanks
# 2  
Old 11-03-2015
This is a linux example for reasonably random dates using /dev/random:
(/dev/urandom gives better random numbers but is overkill for learning)

Code:
date -d `echo @ $(od --read-bytes=4 --address-radix=n --format=u4 /dev/random)| awk '{print $1$2}'`

You need to specify a little more background - what UNIX, what shell? In general it is possible especially using perl and awk
# 3  
Old 11-04-2015
... and for a string with a given length:

Code:
# length 5
head -3 /dev/urandom | tr -cd '[:alnum:]' | cut -c -5

# length 8
head -3 /dev/urandom | tr -cd '[:alnum:]' | cut -c -8


Last edited by ripat; 11-04-2015 at 05:09 AM.. Reason: Typo
# 4  
Old 11-04-2015
@Jim, /dev/random gives the better random numbers but is slower than /dev/urandom!
# 5  
Old 11-04-2015
Code:
n=6; output=$(tr -cd '[:alnum:]' < /dev/urandom | head -c$n)

$ echo $output
ySezMk

# 6  
Old 11-04-2015
With perl
Code:
cat randstring.pl

Code:
#!/usr/bin/perl
$n=shift;
@alpha=( ("A".."Z"), ("a".."z") );
@numeric=( (0..9) );
@allchars=( @alpha, @numeric );
$allrange=$#allchars+1;
for ($i=1; $i <=  $n; $i++) {
  $out.=$allchars[int(rand($allrange))];
}
print "$out\n";

Code:
./randstring.pl 10

# 7  
Old 11-04-2015
Asuming a length of 10

Code:
perl -le 'print map { (a..z,A..Z,0..9)[rand 62] } 0..9'

or:
Code:
n=10
perl -le 'print map { (a..z,A..Z,0..9)[rand 62] } 1..pop' $n


Last edited by Aia; 11-04-2015 at 04:43 PM..
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