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+NSPR_LOG_MODULES
+================
+
+This environment variable specifies which log modules have logging
+enabled.
+
+
+Syntax
+------
+
+::
+
+   moduleName:level[, moduleName:level]*
+
+*moduleName* is the name specified in a
+`:ref:`PR_NewLogModule` <http://www-archive.mozilla.org/projects/nspr/reference/html/prlog.html#25372>`__
+call or one of the handy magic names listed below.
+
+*level* is a numeric value between 0 and 5, with the values having the
+following meanings:
+
+-  0 = PR_LOG_NONE: nothing should be logged
+-  1 = PR_LOG_ALWAYS: important; intended to always be logged
+-  2 = PR_LOG_ERROR: errors
+-  3 = PR_LOG_WARNING: warnings
+-  4 = PR_LOG_DEBUG: debug messages, notices
+-  5: everything!
+
+
+Description
+-----------
+
+Specify a ``moduleName`` that is associated with the ``name`` argument
+in a call to
+`:ref:`PR_NewLogModule` <http://www-archive.mozilla.org/projects/nspr/reference/html/prlog.html#25372>`__
+and a non-zero ``level`` value to enable logging for the named
+``moduleName``.
+
+Special log module names are provided for controlling NSPR's log service
+at execution time. These controls should be set in the
+:ref:`NSPR_LOG_MODULES` environment variable at execution time to affect
+NSPR's log service for your application.
+
+-  **all** The name ``all`` enables all log modules. To enable all log
+   module calls to
+   ```PR_LOG`` <http://www-archive.mozilla.org/projects/nspr/reference/html/prlog.html#25497>`__,
+   set the variable as follows:
+
+   ::
+
+      set NSPR_LOG_MODULES=all:5
+
+-  **timestamp** Including ``timestamp`` results in a timestamp of the
+   form "2015-01-15 21:24:26.049906 UTC - " prefixing every logged line.
+
+-  **append** Including ``append`` results in log entries being appended
+   to the existing contents of the file referenced by NSPR_LOG_FILE.  If
+   not specified, the existing contents of NSPR_LOG_FILE will be lost as
+   a new file is created with the same filename.
+
+-  **sync** The name ``sync`` enables unbuffered logging.   This ensures
+   that all log messages are flushed to the operating system as they are
+   written, but may slow the program down.
+
+-  **bufsize:size** The name ``bufsize:``\ *size* sets the log buffer to
+   *size*.
+
+Examples
+--------
+
+Log everything from the Toolkit::Storage component that happens,
+prefixing each line with the timestamp when it was logged to the file
+/tmp/foo.log (which will be replaced each time the executable is run).
+
+::
+
+   set NSPR_LOG_MODULES=timestamp,mozStorage:5
+   set NSPR_LOG_FILE=/tmp/foo.log
+
+.. _Logging_with_Try_Server:
+
+Logging with Try Server
+-----------------------
+
+-  For **mochitest**, edit variable :ref:`NSPR_LOG_MODULES` in
+   ``testing/mochitest/runtests.py`` before pushing to try. You would be
+   able to download the log file as an artifact from the Log viewer.
+-  (other tests?)