how to use RANDOM command in declared array - arrays

Question

I am trying to build a script where I need to create a password generator with the following parameters :
must be at least 8 characters long but not longer than 16 characters.
must contain at least 1 digit (0-9).
must contain at least 1 lowercase letter.
must contain at least 1 uppercase letter.
must contain exactly one and only one of # # $ % & * + - =
I have two ideas :
The first :
#!/bin/bash
#
#Password Generator
#
#
Upper=('A''B''C''D''E''F''G''H''I''J'K''L''M''N''O''P''Q''R''S''T''U''V''W''X''Y''Z')
Lower=('a''b''c''d''e''z''f''g''h''i''j''k''l''m''o'''p''q''r''s''t''u''v''w''x''y''z')
Numbers=('1''2''3''4''5''6''7''8''9')
SpecialChar=('#''#''$''%''&''*''+''-''=')
if [ S# -eq 0 ] ; then
Pwlength=`shuf -i 8-16 -n 1`
Password=`< /dev/urandom tr -dc A-Za-z0-9$SpecialChar | head -c $Pwlength`
echo "Random Password is being generated for you"
sleep 5
echo "Your new password is : $Password"
exit
The problem is I get characters that I didnt even defined ?
The secound idea :
for((i=0;i<4;i++))
do
password=${Upper[$random % ${#Lower[#]} ] }
password=${Upper[$random % ${#Upper[#]} ] }
password=${Upper[$random % ${#Number[#]} ] }
password=${Upper[$random % ${#SpecialChar[#]} ] }
done
For some reason non of them work ;/

Answer 1

In your first example, move the "-" character to the end of the SpecialChar. I think the definition as you had it results in allowing "+" to "=" (i.e., the value passed to tr reads as "+-="), which accounts for the characters you were not expecting. Alternatively, replace the "-" with "_".
So, try a definition like:
SpecialChar=('#''#''$''%''&''*''+''=''-')

Answer 2

As already mentioned, it would be cleaner and easier to use directly a string to handle list of characters. Handling special characters in an array may cause side effects (for instance getting the list of files in the current directory with the '*' character). In addition, arrays may be difficult to pass as function arguments).
ALPHA_LOW="abcdefghijklmnopqrstuvwxyz"
# Then simply access the char in the string at the ith position
CHAR=${ALPHA_LOW:$i:1}
You could generate upper cases from the lower cases.
ALPHA_UP="`echo \"$ALPHA_LOW\" | tr '[:lower:]' '[:upper:]'`"
The variable which contains a random number is $RANDOM (in capital letters).
sleep 5 is unnecessary.
You need to find a way to keep count of occurrences left for each character type. For more information, I wrote a complete script to do what you described here.

Answer 3

Your first attempt has the following problems:
You are using arrays to contain single strings. Pasting 'A''B''C' is equivalent to 'ABC'. Simply converting these to scalar variables would probably be the simplest fix.
You are not quoting your variables.
You declare Upper, Lower, and Numbers, but then never use them.
Using variables for stuff you only ever use once (or less :-) is dubious anyway.
As noted by #KevinO, the dash has a special meaning in tr, and needs to be first or last if you want to match it literally.
On top of that, the sleep 5 doesn't seem to serve any useful purpose, and will begin to annoy you if it doesn't already. If you genuinely want a slower computer, I'm sure there are people here who are willing to trade.
Your second attempt has the following problems:
The special variable $RANDOM in Bash is spelled in all upper case.
You are trying to do modulo arithmetic on (unquoted!) arrays of characters, which isn't well-defined. The divisor after % needs to be a single integer. You can convert character codes to integers but it's sort of painful, and it's less than clear what you hope for the result to be.
A quick attempt at fixing the first attempt would be
Password=$(< /dev/urandom tr -dc 'A-Za-z0-9##$%&*+=-' | head -c $(shuf -i 8-16 -n 1))
If you want to verify some properties on the generated password, I still don't see why you would need arrays.
while read -r category expression; do
case $Password in
*[$expression]*) continue;;
*) echo "No $category"; break;;
esac
done <<'____HERE'
lowercase a-z
uppercase A-Z
numbers 0-9
specials -##$%&*+=
HERE