Is there a way to create key-value pairs in Bash script?

Question

I am trying to create a dictionary of key value pair using Bash script. I am trying using this logic:

declare -d dictionary defaults write "$dictionary" key -string "$value" 

...where $dictionary is a variable, but this is not working.

Is there a way to create key-value pairs in Bash script?

Answer 1

In bash version 4 associative arrays were introduced.

declare -A arr  arr["key1"]=val1  arr+=( ["key2"]=val2 ["key3"]=val3 ) 

The arr array now contains the three key value pairs. Bash is fairly limited what you can do with them though, no sorting or popping etc.

for key in ${!arr[@]}; do     echo ${key} ${arr[${key}]} done 

Will loop over all key values and echo them out.

Note: Bash 4 does not come with Mac OS X because of its GPLv3 license; you have to download and install it. For more on that see here

Answer 2

If you can use a simple delimiter, a very simple oneliner is this:

for i in a,b c_s,d ; do    KEY=${i%,*};   VAL=${i#*,};   echo $KEY" XX "$VAL; done 

Hereby i is filled with character sequences like "a,b" and "c_s,d". each separated by spaces. After the do we use parameter substitution to extract the part before the comma , and the part after it.