Sink overview
The split of responsibility is deliberate: a logger decides whether to log at all, a sink decides
Console sinks
Console output is the default destination because it's the one that always exists — no file
File sinks
The simplest durable destination — and the one whose failure modes (permissions, unbounded growth,
Rotating and daily
Two different answers to "the log file cannot grow forever": rotate by size whenever the current file
Platform sinks
When the platform already owns log collection — syslog, the systemd journal, the Windows Event Log —
Custom sinks
A custom sink is the supported way to send logs anywhere spdlog doesn't already reach — an in-memory