How to Construct an Array of Arrays in Bash

Question

I'm trying to create an array of arrays in bash. In ruby it would something like:

projects = [
  ["PROJECT_ID_1", "PROJECT_TOKEN_1"],
  ["PROJECT_ID_2", "PROJECT_TOKEN_2"],
  ["PROJECT_ID_3", "PROJECT_TOKEN_3"],
  ["PROJECT_ID_4", "PROJECT_TOKEN_4"]
]

This obviously doesn't work in bash but I can't quite get the syntax right. I know that I'll have to do something like:

declare -a PROJECTS=()
# What goes here?

What is the correct way of doing this in bash?

btw -- all-caps names are used for variables with meaning to the system or shell, whereas lower-case names are [reserved for application use](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html) -- that's explicitly specified for environment variables, but assigning to a shell variable will overwrite any like-named environment variable, so it applies in both places. — Charles Duffy, Jan 13 '17 at 18:43
For your specific use case, use two separate native arrays: `project_ids=( A B C D ); project_tokens=( W X Y Z )`; then: `for idx in "${!project_ids[@]}"; do project_id=${project_ids[$idx}; project_token=${project_tokens[$idx]}; echo "Project with id $project_id has token $project_token"; done` — Charles Duffy, Jan 13 '17 at 18:46
Mind you, in bash 4.x you could also just use a single associative array to map straight from IDs to tokens: `declare -A project_tokens=( [A]=W [B]=X [C]=Y [D]=Z )`; then `"${!project_tokens[@]}"` will expand to the list of IDs, and `"${project_tokens[$id]}` will map an ID to a token. — Charles Duffy, Jan 13 '17 at 18:47

How to Construct an Array of Arrays in Bash

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