log_listener CLI

The log_listener binary is included in all device builds that include pkgfs and is currently the primary tool used by engineers to interactively read a live log stream. In-tree developers usually invoke it with ffx log.

Flag Notes
--only <comma-separated-words> Include lines containing at least one of the specified words. If this is not set, it has no effect.
--suppress <comma-separated-words> Exclude lines containing any of the specified words.
--select <comma-separated-component-interests> Specify the runtime log level for components as 'component interest' using the form <component>#<interest> where component is a component selector (a component moniker that might include wildcards or a recursive glob in the last segment) and interest is the specified selection criteria, one of FATAL|ERROR|WARN|INFO|DEBUG|TRACE giving the desired 'log-level'. Multiple component interest selections are delimited by commas.
--begin <comma-separated-words> Include blocks starting with at least one of the specified words. Pair with the --end flag. Defaults to off.
--end <comma-separated-words> Exclude blocks starting with at least one of the specified words. Pair with the --begin flag. Defaults to off.
--tag <string> Tag(s) to include. Use multiple times for multiple tags. By default no tag filtering is performed, only specified tags are allowed if any are specified.
--ignore-tag <string> Tag(s) to ignore. Use multiple times for multiple tags.
--pid <integer> Only print logs from the given process koid.
--tid <integer> Only print logs from the given thread koid.
--pretty yes Activate colors.
--hide_metadata yes Hides extraneous metadata (such as PID, TID) from log output. When paired with --pretty, lines are colorized by severity.
--severity <level> Minimum severity to include. Defaults to INFO.

Does not have any impact on the logs produced by components.

<level> must be one of TRACE|DEBUG|INFO|WARN_ERROR|FATAL.

--file <string> Path where logs will be written. By default logs are written to stdout.
--file_capacity <integer> The maximum allowed amount of disk space to consume. Once the file being written to reaches half of the capacity, it is moved to FILE.old and a new log file is created.

Defaults to 64000. If --file is not specified, it has no effect.

Setting to 0 disables this functionality.

--startup_sleep <integer> Sleep for this number of milliseconds on program startup.
--clock <Monotonic|UTC|Local> Clock to use when printing timestamps.

Monotonic (default): Monotonic time reported by the kernel.

UTC: UTC time as reported by the runtime.

Local: Localized wall time.

--time_format <format> If --clock is not MONOTONIC, specify timestamp format.

See the chrono crate's docs for format specifiers.

Defaults to "%Y-%m-%d %H:%M:%S".

--since_now yes Ignore all logs from before this command is invoked.
--dump_logs yes Exit after printing already-available logs.
--help | -h Prints usage.