Print if argument matches regex:

you can do this with: RUST_LOG='[{topic=.small_bedroom:piano.}]=trace,info'

that will print every log at trace level or higher that is inside an

instrumented function with an argument topic for which the regex

.small_bedroom. evaluates as true

Print if in function:

RUST_LOG='[function_name]=trace'

RUST_LOG='[parse_message]=trace,[{device_name=.:radi.}]=trace,[{friendly_name=.:radi.}]=trace,info'

/// # Note /// If the service runs under systemd it logs to the sysjournal. Then: /// /// The standard journald CODE_LINE and CODE_FILE fields are automatically /// emitted. A TARGET field is emitted containing the event’s target. For /// events recorded inside spans, an additional SPAN_NAME field is emitted /// with the name of each of the event’s parent spans. User-defined fields /// other than the event message field have a prefix applied by default to /// prevent collision with standard fields. /// /// example: journalctl -fu desk-sensors /// --output-fields=CODE_FILE,CODE_LINE,MESSAGE -o cat