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How to Use awk Associative Arrays for Counting and Grouping
Count, group and deduplicate with awk associative arrays: count[$1]++, loop over keys, sort the output, test membership and use composite keys.
5 min read
Tag
arrays
11 posts
Bash
How to Return an Array From a Bash Function the Right Way
Return an array from a Bash function with a global, a nameref, or captured output, and see why return itself only carries an exit status from 0 to 255.
6 min read
Bash
How to Pass an Array to a Bash Function and Read It Back
Pass a Bash array to a function by expanding it, by name with a nameref, or through a global, and learn which method survives spaces and keeps the original.
6 min read
Bash
How to Add and Remove Items in a Bash Array by Index
Append, insert and remove Bash array items by index with +=, slicing and unset, and see why unset leaves a gap that you must repack.
6 min read
Bash
How to Loop Over an Array in Bash Without Breaking Elements
Loop over a Bash array with for and quoted expansion, iterate indexes and associative keys, and avoid the unquoted pattern that splits items with spaces.
6 min read
Bash
How to Use Arrays in Bash From the Basics to Array Slicing
Learn Bash arrays from declaration to slicing: indexed and associative arrays, counting items, quoting expansions, and when a plain string is better.
5 min read
Bash
How to Get the Length of a String or Array in Bash
Get the length of a string or an array in Bash with ${#var} and ${#arr[@]}, count bytes versus characters, and avoid the common off-by-one with indexes.
5 min read
Bash
How to Check If a Key Exists in a Bash Associative Array
Test whether a key exists in a Bash associative array with -v, the +x expansion, or a default value, and tell a missing key from a key with an empty value.
6 min read
Bash
How to Loop Over Keys and Values of a Bash Dictionary
Loop over a Bash associative array by key, by key and value, and in sorted order, and see why the order is not guaranteed and how to keep it stable.
6 min read
Bash
How to Use Associative Arrays in Bash With declare A
Create and use an associative array in Bash with declare -A, assign and read keys, list keys and values, and avoid the Bash 3.2 and quoting traps.
6 min read
Bash
How to Remove Duplicates From a Bash Array and Keep Order
Remove duplicates from a Bash array while keeping first-seen order, using an associative array, sort -u, or awk, and know which one fits your Bash version.
6 min read