Random variables

Shell Programming and Scripting
1

I need to create a random String to save in a variable.

var=`??????`

So I want to replace ?????? with random 8 chars for instance:

is96789h

only letters and numbers

Is there an easy way to do this?

Thanks as always

DV

2 
var=`perl -MList::Util=shuffle -le '@s = shuffle (a..z, 0..9); print @s[0..7]'`
1 Like
3

Hi.

Here are two more solutions, both using different perl modules.

Observations: the shuffle would not return any duplicates, the Data/Random would not return duplicates until the result is quite long -- longer than the source strings (this is partly a guess and partly observation), the Data/Random/String can return duplicates as seen below.

The choice depends on the application.

#!/usr/bin/env bash

# @(#) s1	Demonstrate perl modules for string of random characters.

pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C perl

var=`perl -MList::Util=shuffle -le '@s = shuffle (a..z, 0..9); print @s[0..7]'`
pl "Random list as string (shuffle): $var"

var=$(perl -e 'use Data::Random qw(:all);print join("",rand_chars(set => 'alphanumeric', size => 8)),"\n";' ) 
pl " Random list as string (Random): $var"

var=$(perl -e 'use Data::Random::String; print Data::Random::String->create_random_string(length=>8, contains=>"alphanumeric"),"\n";')
pl " Random string (String): $var"

exit 0

producing:

% ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0.8 (lenny) 
bash GNU bash 3.2.39
perl 5.10.0

-----
Random list as string (shuffle): g2lto9kn

-----
 Random list as string (Random): s6S5A8tD

-----
 Random string (String): 6E6wfo0C

Best wishes ... cheers, drl

4 
#!/bin/bash

ary=({a..z} {A..Z} {0..9})

for i in {0..7}; do
    echo -n ${ary[RANDOM%${#ary[@]}]}
done
echo