webOS Open Source Edition (OSE) provides a collection of libraries and tools that help you trace and debug your apps and services. This section describes how to use these libraries and tools for the following tasks that are required to make the most of the webOS OSE logging framework.
To view logs, different methods are used depending on which logging daemon is enabled in the platform. The two logging daemons that are available in the webOS OSE platform are journald and pmlogd.
journald is a sub-component of systemd, which is responsible for event logging and runs as the systemd-journald daemon. journald collects log data that are logged via stdout/stderr and kmsg as well as log messages formatted by PmLogLib.
pmlogd is a logging daemon that implements a subset of RFC 3164 (The BSD syslog Protocol), intended to efficiently address the needs for webOS OSE embedded devices. pmlogd only handles the log messages formatted by PmLogLib.
The default status of logging daemons vary by platform version:
On webOS OSE 2.1.0 or higher, journald is enabled and pmlogd is disabled by default.
Up to webOS OSE 2.0.0, pmlogd is enabled and journald is disabled by default.