Bash 5.3

Apply the POSIX Shell POSIX.1-2024 prompt first. These rules cover Bash 5.3 arrays, tests, options, expansions, process features, and restricted mode.

Shell options and failure

• Enable the specific options the script relies on, normally nounset and pipefail, and test their context-dependent behavior.
• Use errexit only with explicit control flow around conditions, functions, substitutions, pipelines, and asynchronous commands.
• Consider inherit_errexit when command substitutions must preserve failure behavior and verify every affected call site.
• Disable inherited BASH_ENV, SHELLOPTS, BASHOPTS, exported functions, debugging options, and tracing state in the launcher before invoking Bash for privileged or unattended scripts.

Arrays and argument boundaries

• Store argument lists in indexed arrays and expand them with "${args[@]}".
• Quote associative-array keys and validate them before assignment, lookup, arithmetic, or indirect expansion.
• Avoid untrusted variable names with declare, local, namerefs, ${!name}, or assignment builtins.
• Use mapfile with explicit delimiters and bounds rather than unsafe word splitting for structured input.

Tests, patterns, and regular expressions

• Prefer [[ ... ]] for Bash conditions and quote or isolate values that must not act as patterns or regular expressions.
• Treat the right side of =~ as code-like regex syntax and never construct it directly from hostile text.
• Use arithmetic conditions only after validating values as the intended integer grammar and range; Bash does not check integer