Logger - yet an other Variable Logging Utility

The Logger (logger.c)

The logger is a utility to write the history of object parameters. For all drivers based on pardef it is automatically switched on. The data is logged typically every 5 seconds to a file, but only changes are stored in order to save disk space. The file specification for the logfiles is:

<logger base path>/<variable name>/MM-DD.log

Files older than one year will be overwritten. The variable name is the object name for the basic value of the object or <object name>.<parameter name> for the parameters. Important parameter names might be configured to have a more descriptive name.

Syntax of the Log Files

First there is a header line, containing the date and some additional information:

isdst

0/1 when daylight saving time is in effect or not

period

the minimal interval between logged values

exact

0: plot points should be connected with a straight line, 1: plot curves should have only horizontal and vertical lines

#2005-10-30 00:00:00 isdst 1 period 5 exact 0
00:00:00<tab>100.72
00:00:05<tab>100.73
00:01:10<tab>100.73
00:01:15<tab>100.74
00:01:20<tab>100.73

      ...                                        many lines omitted

02:59:55<tab>100.56
#isdst 0                                         change of daylight saving time
02:00:00<tab>100.58

      ...                                        many lines omitted

07:55:00<tab>100.58                              the server was shut down
#isdst 0 period 5 exact 0                        the server restarts at 8:30
07:55:05<tab>                                    the shutdown time and an empty value
08:30:00<tab>99.95                               the first logged value after startup

The Log Reader (logreader.c)

There is also a utility to read the logged data through the SICS server.