Changes between Version 5 and Version 6 of Logging

Timestamp:

2012-10-05T09:00:20Z (12 years ago)

Author:

Vojtech Horky

Comment:

Write section about changing log level at run-time

Logging

@@ -78 +78 @@
 == Changing reported level at run-time ==
 
-TODO - logset
+It is also possible to change reported log level at run-time. For that the user shall use the `logset` utility. The utility is controlled purely via its command-line arguments - one of them is always the name of the level that is supposed to be set.
+
+To change the default reporting level, simply run `logset` with the level name - following would make the system very quiet.
+{{{
+logset fatal
+}}}
+
+To change the reporting level of a certain log, run `logset` with the log name followed by the level name. For example, to make devman more verbose, run the following:
+{{{
+logset devman debug2
+}}}
+
+It is also possibly to target a nested log - simply separate individual names with a slash (like in a file name).
+
+'''Example (tester logger2)''': To demonstrate how setting log levels at run-time works, you shall open at least three terminals. In one, start the `tester` with `logger2` test. This test only prints messages at different levels to different logs.
+
+In the second, you shall monitor the tester log - either by `cat`ting `/log/tester` or you can switch to kernel console (if you configure HelenOS without GUI, seventh console shall display that output).
+
+And in the third console you can issue the `logset` to see what happens.
+
+By default, you would see that `tester` continuously prints errors, warnings and notes into three logs: the default one (i. e. `tester`), `alpha` and `bravo` (`tester/alpha` and `tester/alpha/bravo`).
+
+Running
+{{{
+logset tester/alpha fatal
+}}}
+would mute all the output to `alpha` and `alpha/bravo` logs. The reason why `bravo` was muted as well is because it is a child of `alpha` and has to respect its settings (unless explicitly overridden).
+
+But it is possible to explicitly enable `bravo` output. If we ran
+{{{
+logset tester/alpha/bravo warn
+}}}
+the `alpha` is still muted but together with the original `tester` messages, `bravo` warnings are interleaved.
+
 
 == Using the C API ==