I am trying to get the size of an array, but I don't know the array name until runtime (it's built dynamically based on a list from a file), so I am trying to use bash indirection with ${!var}.
This answer comes very close (How to iterate over an array using indirect reference?), but falls short of making the array size ${#var[@]} work
Note: I am trying to avoid eval, and I have Bash >=4.0 but <4.3 (so I cannot use declare -n). And I'd rather not iterate over the whole array to calculate size, as it can get very large.
What I have working:
# Declare dynamic arrays
for env in INT PROD; do
declare -A "values$env"
done
# Creates 'valuesINT[]' and valuesPROD[]' arrays
while IFS=$'\n'=, read -r key env val; do
# Assigns val to index key in dynamic array name values$env
declare "values$env[$key]=$val"
done <my_file
# Output arrays
for env in INT PROD; do
valuesArrName="values${env}[@]"
echo ${!valuesArrName} # this works to output all values
done
So I can use indirection with ${!valuesArrName} to output values
But I cannot use indirection to get array size:
valuesArrName="values${env}[@]"
echo ${#!valuesArrName}
# OUTPUT: ${#!valuesArrName}: bad substitution
valuesArrName="#values${env}[@]"
echo ${!valuesArrName}
# OUTPUT: #valuesINT[@]: bad substitution
valuesArrName="#values${env}"
echo ${!valuesArrName[@]}
# OUTPUT: no error, but always 0
