Bashspecific

Bashspecific refers to features, constructs, and behaviors of the Bash shell that are not part of the POSIX sh standard and are not guaranteed in other shells. The term is used informally to denote elements that depend on Bash, rather than portable shell scripting.

Common examples include arrays (indexed and associative) and their expansions; the extended test construct [[ ... ]]; process substitution using <( ... ) and >( ... ); brace expansion {a,b,c}; arithmetic expansion $(( ... )); advanced parameter expansion such as ${var^^}, ${var,,}, and ${var//pattern/replacement}; string manipulation with parameter expansion; here strings and here documents with enhanced features; command substitution $( ... ); history expansion using ! and !!; and interactive line editing with Readline features.

Bashspecific features improve scripting capabilities but reduce portability to other shells. To write portable scripts, avoid Bashspecific constructs or use an explicit Bash shebang (#!/usr/bin/env bash) and test for Bash availability. You can reduce some differences by enabling POSIX mode with set -o posix, though not all Bashisms are eliminated.

In practice, Bashspecific is contrasted with portable POSIX sh techniques, and with the broader concept of bashisms describing constructs that rely on Bash. The term emphasizes the boundary between Bash's extended capabilities and more portable shell scripting.

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