Validates backup archives before extraction and rejects members that traverse paths or create unsafe links. This is a self-contained safety utility that could be lifted into any backup/restore or file-ingestion system handling untrusted archives.

Normalizes retention-day values and local backup paths, rejecting relative paths, '..', and root before scheduling or writing backups. Also prepares run directories and prunes expired backup directories. The validation helpers are reusable across backup schedulers and data-retention tooling.

Changes system account passwords by piping credentials to chpasswd via stdin instead of passing them through shell command strings, and uses a single-use token flow for remote password requests. Demonstrates a reusable credential-change pattern that avoids command injection and shell-history leakage.

Parses and validates OpenSSH authorized_keys lines, supports safe deletion with atomic file operations, and rejects malformed keys. This is a reusable utility for any server-management system that needs trustworthy SSH public-key CRUD.

Idempotently injects deny rules for sensitive files such as .env and .git into OpenLiteSpeed vhost configurations using marker boundaries and atomic file replacement. The marker-based, idempotent config-injection pattern generalizes well to safe live configuration management.