How to pass array as an argument to a function in Bash

Question

As we know, in bash programming the way to pass arguments is $1, ..., $N. However, I found it not easy to pass an array as an argument to a functio

Answer 1

You can pass an array by reference to a function in bash 4.3+. This comes probably from ksh, but with a different syntax. The key idea is to set the -n attribute:

show_value () # array index
{
    local -n array=$1
    local idx=$2
    echo "${array[$idx]}"
}

This works for indexed arrays:

$ shadock=(ga bu zo meu)
$ show_value shadock 2
zo

It also works for associative arrays:

$ days=([monday]=eggs [tuesday]=bread [sunday]=jam)
$ show_value days sunday
jam

See also declare -n in the man page.