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?
This question is related to
bash
shell
associative-array
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
For persistent key/value storage, you can use kv-bash, a pure bash implementation of key/value database available at https://github.com/damphat/kv-bash
Usage
git clone https://github.com/damphat/kv-bash
source kv-bash/kv-bash
Try create some permanent variables
kvset myName xyz
kvset myEmail [email protected]
#read the varible
kvget myEmail
#you can also use in another script with $(kvget keyname)
echo $(kvget myEmail)
in older bash (or in sh) that does not support declare -A, following style can be used to emulate key/value
# key
env=staging
# values
image_dev=gcr.io/abc/dev
image_staging=gcr.io/abc/stage
image_production=gcr.io/abc/stable
img_var_name=image_$env
# active_image=${!var_name}
active_image=$(eval "echo \$$img_var_name")
echo $active_image
If you can use a simple delimiter, a very simple oneliner is this:
for i in a,b c_s,d ; do
KEY=${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.
In bash, we use
declare -A name_of_dictonary_variable
so that Bash understands it is a dictionary.
For e.g. you want to create sounds dictionary then,
declare -A sounds
sounds[dog]="Bark"
sounds[wolf]="Howl"
where dog and wolf are "keys", and Bark and Howl are "values".
You can access all values using : echo ${sounds[@]} OR echo ${sounds[*]}
You can access all keys only using: echo ${!sounds[@]}
And if you want any value for a particular key, you can use:
${sounds[dog]}
this will give you value (Bark) for key (Dog).
Source: Stackoverflow.com