Normalize JSON and JSONL output

docs/automation-examples.md

@@ -4,6 +4,12 @@ These examples are intended as starting points for local scripts and
 infrastructure automation. They assume the single `geth` executable is on
 `PATH`.
 
+Use `--json` when one process invocation produces one result that will be
+parsed as a complete document. Use `--jsonl` for line-oriented shell pipelines:
+each current command writes one compact object on one physical line. The flags
+are mutually exclusive, and failures use the same `type: "error"` envelope and
+return a nonzero exit status in either mode.
+
 ## Shell
 
 Initialize a home, start the daemon in a user-owned process, wait for control,
@@ -25,6 +31,13 @@ geth doctor --json
 geth status --json
 ```
 
+For a compact line suitable for an append-only log or `jq -c` pipeline:
+
+```sh
+geth status --jsonl >>geth-status.jsonl
+tail -n 1 geth-status.jsonl | jq -r '.type'
+```
+
 Create a backup into a separate directory and validate that it can restore to a
 new home: