---
name: feedback-no-sed-multiline
description: Never use sed for multi-line config edits — use Python or heredoc writes to avoid mangling YAML/config files
metadata: 
  node_type: memory
  type: feedback
  originSessionId: d51db7ad-b5b8-40f4-b56a-9585fd13b303
---

Do not use `sed -i` for inserting multi-line blocks into config files (YAML, TOML, etc.). The newline handling breaks formatting and causes service outages.

**Why:** sed collapsed a multi-line OIDC client block into a single line, breaking Authelia's configuration.yml and causing a crash loop.

**How to apply:** For any config file edit that spans multiple lines, use Python (read/replace/write) or `tee` with a heredoc. Only use sed for single-line substitutions where the replacement fits on one line. Related: [[feedback-caddyfile-inode]]