Passing multiple distinct arrays to a shell function

Question

Because shells other than ksh do not support pass-by-reference, how can multiple arrays be passed into a function in bash without using global variables, and in a way which

Answer 1

Can also be done using eval:

declare -a a=( "aa bb" 123 '$ $ $' )
declare -a b=( "bb cc" 456 '###' )

printf "\n%s\n" 'a before sub:'
printf "'%s'\n" "${a[@]}"
printf "\n%s\n" 'b after sub:'
printf "'%s'\n" "${b[@]}"


sub ()
{
  eval a0=\${$1[0]}                     # get value a[0]
  eval b1=\${$2[1]}                     # get value b[1]
  echo "a[0] = '$a0'"
  echo "b[1] = '$b1'"

  eval $1[0]='a---a'                    # set value a[0]
  eval $2[1]=999                        # set value b[1]

} # ----------  end of function sub  ----------

sub a b     # call function sub

printf "\n%s\n" 'a after sub:'
printf "'%s'\n" "${a[@]}"
printf "\n%s\n" 'b after sub:'
printf "'%s'\n" "${b[@]}"

The output:

a before sub:
'aa bb'
'123'
'$ $ $'

b after sub:
'bb cc'
'456'
'###'
a[0] = 'aa bb'
b[1] = '456'

a after sub:
'a---a'
'123'
'$ $ $'

b after sub:
'bb cc'
'999'
'###'