#STEP 1 -- some arbitrary words to make some variable names from:
sasha@reactor:~$ var1='hello'
sasha@reactor:~$ var2='goodbye'
sasha@reactor:~$ var3='blah'
sasha@reactor:~$ var4='leopard'

#STEP 2 -- Form some strings from some of the arbitrary pieces:
sasha@reactor:~$ echo ${var1}_${var3}_${var2}
hello_blah_goodbye <--fresh string
sasha@reactor:~$ echo ${var1}_${var4}_${var2}
hello_leopard_goodbye <--fresh string
sasha@reactor:~$

#STEP 3 -- If those strings were actually variables...
sasha@reactor:~$ echo \$${var1}_${var3}_${var2} 
$hello_blah_goodbye <--like this
sasha@reactor:~$ echo \$${var1}_${var4}_${var2}
$hello_leopard_goodbye <--or like this
sasha@reactor:~$

#STEP 4 ...they would be empty variables; we haven't set them to anything:
sasha@reactor:~$ echo $hello_blah_goodbye

sasha@reactor:~$ echo $hello_leopard_goodbye

sasha@reactor:~$ 

#STEP 5 -- Give the new variables some values.. 
# If the value is multiple words (contains spaces) we must include "quotes" around the value: 
sasha@reactor:~$ eval ${var1}_${var3}_${var2}="'weird greeting'"
sasha@reactor:~$
# if there's no spaces, we don't need quotes:
sasha@reactor:~$ eval ${var1}_${var4}_${var2}='carnivore' <--quotes here optional
sasha@reactor:~$

#STEP 6 -- Now they aren't empty; to see the value of a variable, we use echo:
sasha@reactor:~$ echo $hello_blah_goodbye
weird greeting
sasha@reactor:~$ echo $hello_leopard_goodbye
carnivore
sasha@reactor:~$ 

#STEP 7 -- Create an echo command for the shell to execute, to return to us the value
# of the variable, when different combinations of our arbitrary words might comprise the variable name:
sasha@reactor:~$ echo "echo \$${var1}_${var3}_${var2}" <--quotes are optional, but safer!
echo $hello_blah_goodbye <-- a command for the shell to run
sasha@reactor:~$  echo echo \$${var1}_${var4}_${var2} <--no quotes, but still works
echo $hello_leopard_goodbye <-- another command for the shell to run
sasha@reactor:~$ 

# We can run those commands ourselves, like in STEP 6 above:
sasha@reactor:~$ echo $hello_blah_goodbye
weird greeting
sasha@reactor:~$ echo $hello_leopard_goodbye
carnivore
sasha@reactor:~$

#STEP 9 -- ..or the shell can run them for us (as if within a script) and give us the value.
# To get the value of a variable made of various arbitrary parts, we need eval
# to evaluate the parts and string them together:
sasha@reactor:~$ hi_and_goodbye=$(eval echo \$${var1}_${var3}_${var2})
sasha@reactor:~$ echo $hi_and_goodbye
weird greeting
# Or if we know the parts, we can be direct, and don't need eval:
sasha@reactor:~$ cat_thing=$(echo $hello_leopard_goodbye)
sasha@reactor:~$ echo $cat_thing
carnivore
sasha@reactor:~$

# The REAL ARRAY method:
# first, fill the array:
for i in $(seq 0 10); do
array[$i]="real array element $i here!"
done
# now, see the values of the array elements:
for i in $(seq 0 10); do
the_content="${array[i]}"
echo $the_content
done

# The NON-ARRAY method:
# be wary of using exclamation point in the fake element
# because bash tries to execute it as a history event. If you want
# to use ! in your fake array element, follow it with a newline (like I did here) or whatever.
# see man bash for details of the ! event operator.

# first, define the fake array's name:
fake_array='fake_array'
# fill the phony array:
for i in $(seq 0 10); do
eval ${fake_array}${i}="'phoney element $i here!
'"
done
# now, see the values of the 'phony array's elements:
for i in $(seq 0 10); do
the_content=$(echo $(eval echo \$$fake_array${i}))
echo $the_content
done

# The REAL ARRAY method:
sasha@reactor:~$ for i in $(seq 0 10); do 
> array[$i]="real array element $i here"
> done
sasha@reactor:~$ for i in $(seq 0 10); do
> the_content="${array[i]}"
> echo $the_content
> done
real array element 0 here
real array element 1 here
real array element 2 here
real array element 3 here
real array element 4 here
real array element 5 here
real array element 6 here
real array element 7 here
real array element 8 here
real array element 9 here
real array element 10 here
sasha@reactor:~$ 

# The NON-ARRAY method:
sasha@reactor:~$ fake_array='fake_array'
sasha@reactor:~$ for i in $(seq 0 10); do
> eval ${fake_array}${i}="'phoney element $i here!
> '"
> done
sasha@reactor:~$ for i in $(seq 0 10); do
> the_content=$(echo $(eval echo \$$fake_array${i}))
> echo $the_content
> done
phoney element 0 here!
phoney element 1 here!
phoney element 2 here!
phoney element 3 here!
phoney element 4 here!
phoney element 5 here!
phoney element 6 here!
phoney element 7 here!
phoney element 8 here!
phoney element 9 here!
phoney element 10 here!
sasha@reactor:~$

#The REAL ARRAY method:
\u@\h:\w$ for i in $(seq 0 10); do
> array[$i]="real array element $i here"
> done
dash: array[0]=real array element 0 here: not found
dash: array[1]=real array element 1 here: not found
dash: array[2]=real array element 2 here: not found
dash: array[3]=real array element 3 here: not found
dash: array[4]=real array element 4 here: not found
dash: array[5]=real array element 5 here: not found
dash: array[6]=real array element 6 here: not found
dash: array[7]=real array element 7 here: not found
dash: array[8]=real array element 8 here: not found
dash: array[9]=real array element 9 here: not found
dash: array[10]=real array element 10 here: not found
\u@\h:\w$ 

# no point trying to get the contents; it's obvious the array is non-existent.

#The FAKE ARRAY method:
\u@\h:\w$ fake_array='fake_array'
\u@\h:\w$ for i in $(seq 0 10); do
> eval ${fake_array}${i}="'phoney element $i here!
> '"
> done
\u@\h:\w$ for i in $(seq 0 10); do
> the_content=$(echo $(eval echo \$$fake_array${i}))
> echo $the_content
> done
phoney element 0 here!
phoney element 1 here!
phoney element 2 here!
phoney element 3 here!
phoney element 4 here!
phoney element 5 here!
phoney element 6 here!
phoney element 7 here!
phoney element 8 here!
phoney element 9 here!
phoney element 10 here!
\u@\h:\w$ 

# Success!