Associative arrays (aka hashes) can be used since Bash v4 and need a declaration like this Bash & ksh: echo ${#MYARRAY[@]} Test if a key exist. There are the associative arrays and integer-indexed arrays. In Bash, there are two types of arrays. Hashes in Bash. Elements in arrays are frequently referred to by their index number, which is the position in which they reside in the array. Arrays to the rescue! The label may be different, but whether called “map”, “dictionary”, or “associative array… See below for accessing the different properties of an array. You can assign values to arbitrary keys: $ A common use is for counting occurrences of some strings. Indexed arrays are accessed the same way as “Hashes”. (by the way, bash hashes don't support empty keys). Bash associative arrays are supported in bash version 4. Dictionary / associative arrays / hash map are very useful data structures and they can be created in bash. Bash & ksh: Before use associative array needs to be declared as shown below: declare -A hash hash=(["k1"]="v1" ["k2"]="v2") dictionaries were added in bash version 4.0 and above. Get the length of an associative array. Bash & ksh: if [[ -v "MYARRAY[key5]" ]] ; then # code if key exist else # code if key does not exist fi Test if the value for a key is an empty string. An associative array is an array which uses strings as indices instead of integers. Copying associative arrays is not directly possible in bash. To iterate over the key/value pairs you can do something like the following example # For every… To check the version of bash run following: To access the keys of an associative array in bash you need to use an exclamation point right before the name of the array: ${!ARRAY[@]}. But what if you need more than few variables in your bash scripts; let’s say you want to create a bash script that reads a hundred different input from a user, are you going to create 100 variables? There is another solution which I used to pass variables to functions. However, I find that things like: Declare and initialize associative array. We will go over a few examples. You could use the same technique for copying associative arrays: So far, you have used a limited number of variables in your bash script, you have created few variables to hold one or two filenames and usernames.. These index numbers are always integer numbers which start at 0. An associative array lets you create lists of key and value pairs, instead of just numbered values. The best solution probably is, as already been pointed out, to iterate through the array and copy it step by step. Here is a quick start tutorial for using bash associative arrays. A few Bourne-like shells support associative arrays: ksh93 (since 1993), zsh (since 1998), bash (since 2009), though with some differences in behaviour between the 3. They work quite similar as in python (and other languages, of course with fewer features :)). There are at least 2 ways to get the keys from an associative array of Bash. The values of an associative array are accessed using the following syntax ${ARRAY[@]}. Arrays in Bash. Bash: Associative array initialization and usage Just as in other programming languages, associative arrays in Bash are useful for search, set management, and keying into a list of values. Let’s start with an example associative array: $ declare -A aa $ aa["foo"]=bar $ aa["a b"]=c. Bash, however, includes the ability to create associative arrays, and it treats these arrays the same as any other array. For the record, in zsh, to turn two arrays into an associative array/hash, you'd do: typeset -A hash hash=("${(@)array1:^array2}") Where ${array1:^array2} is the array zipping operator and the @ parameter expansion flag is used to preserve empty elements (in double quotes, similar to "$@"). Same way as “ Hashes ” Test if bash associative array key exist, to iterate through array... 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