Get value from array of dictionaries bash

Question

I'm learning how bash scripting and I need to know how to get a value from an array of dictionaries. I did this for the declaration:

declare -a persons
declare -A person
person[name]="Bob"
person[id]=12
persons[0]=$person

If I do the following it works fine:

echo ${person[name]}
# Bob

But when I try to access to the values from the array it doesn't work. I tried these options:

echo ${persons[0]}
# empty result
echo ${persons[0][name]}
# empty result
echo persons[0]["name"]
# persons[0][name]
echo ${${persons[0]}[name]} #It could have worked if this work as a return
# Error

And I dont know what more try. Any help would be appreciated!

Thank you for reading!

Bash version: 4.3.48

bash doesn't support 2 dimensional arrays. Use perl, php, python etc. — anubhava
– anubhava, Commented Jun 22, 2017 at 10:28
@anubhava Then if i want for example do a curl and save the output to a variable could I access to some value of the variable? — Alberto
– Alberto, Commented Jun 22, 2017 at 10:55
Other languages will have their own libraries for fetching URLs internally; you won't need to execute an external program like curl. — chepner
– chepner, Commented Jun 22, 2017 at 11:24

sjsam · Accepted Answer · 2017-06-22 11:16:54Z

1

The notion of a multi-dimensional array is not supported in bash, So

${persons[0][name]}

will not work. However, from Bash 4.0, bash has associative arrays, which you seemed to have tried, which suits your test case. For example you may do it like below:

#!/bin/bash
declare -A persons
# now, populate the values in [id]=name format
persons=([1]="Bob Marley" [2]="Taylor Swift" [3]="Kimbra Gotye")
# To search for a particular name using an id pass thru the keys(here ids) of the array using the for-loop below

# To search for name using IDS

read -p "Enter ID to search for : " id
re='^[0-9]+$'
if ! [[ $id =~ $re ]] 
then
 echo "ID should be a number"
 exit 1
fi
for i in ${!persons[@]} # Note the ! in the beginning gives you the keys
do
if [ "$i" -eq "$id" ]
then
  echo "Name : ${persons[$i]}"
fi
done
# To search for IDS using names
read -p "Enter  name to search for : " name
for i in "${persons[@]}" # No ! here so we are iterating thru values
do
if [[ $i =~ $name ]] # Doing a regex match
then
  echo "Key : ${!persons[$i]}" # Here use the ! again to get the key corresponding to $i
fi
done

edited Jun 22, 2017 at 11:16

answered Jun 22, 2017 at 10:57

sjsam

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6 Comments

Alberto Over a year ago

So in this case, I could save the id as Index? but what if I want to search the id if I only have the name?

sjsam Over a year ago

@AlbertoLópezPérez You can just reverse the for loop, wait for my edit.

Alberto Over a year ago

Okay, this works in my case but if instead of ids were for example... country this would be different I think. If I'm wrong correct me please.

sjsam Over a year ago

Well, if you have to have country->name combination, you can't go with this method.. Because country is not unique for an individual.

Alberto Over a year ago

Yes but what i really wanted was something like: person[name]=Bob person[country]=Spain persons[0]=person To have a structured variable for later do a foreach or something and do something with the data.

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