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Bash Cookbook: Parameter Expansion, Arrays, Associative Arrays, Arithmetic Traps and getopts

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Self-Hosting & Infra intermediate 7 min read $0.01 Updated 2026-10-20

Executed in bash: ${var##*/}, %, %%, //, ^^, substring, :- versus - versus :=, quoted versus unquoted array loops, negative indexes, associative arrays, read -ra splitting, 010 as octal, -7/2, BASH_REMATCH, local scope leaks and getopts error handling.

Strip extensions, set defaults, split strings, loop over arrays with spaces, count in octal-safe arithmetic and parse flags with getopts. Every expansion is shown with its real output from bash.

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#bash#shell#scripting#arrays#getopts

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