Thursday 22 August 2013

Log Files

Every program generates a log file when it is run. By default, this file will be named after the calling program (e.g. will produce a log called gasp.log) but this can be changed with the log=FILE option. The basefile=X option will also set the base name of the log file, as well as the main results files (for most programs). Logs will be appended unless the newlog (or newlog=T) option is used.

The log file records information that may help subsequent interpretation of results or identify problems. Each line is tab delimited in the form:

#XXX    HH:MM:SS    Log Message.

Where #XXX is an identifier that can be used to parse out specific types of information, HH:MM:SS is the runtime in hours, minutes and seconds, and Log Message will be something (hopefully) informative.

All log files start with the same few lines:

#~~#    #~~#    #~~#
#LOG 00:00:00 Activity Log for PROGRAM X.X: DATE TIME YEAR
#DIR 00:00:00 Run from directory: RUNPATH
#ARG 00:00:00 Commandline arguments: ARGLIST
#CMD 00:00:00 Full Command List: [FULL ARGLIST]

This should contain all the information required to repeat the analysis:

  • PROGRAM X.X: DATE TIME YEAR will have the program name, version number and the date/time of the run.
  • RUNPATH is the directory from which the program was run.
  • ARGLIST is the list of command-line arguments given to the program.
  • FULL ARGLIST is the full list of command-line arguments including any arguments read in from ini files.

The last line can help identify the source of any unexpected behaviour due to default settings etc.

(The #~~# #~~# #~~# line is simply to act as a separator if appending an existing log file.)

If the program runs to completion successfully, it will end with another #LOG line:


If this line is not present then something went wrong during the run (see Error Messages, below - or it is still in progress. Other information is also recorded along with the runtime (HH:MM:SS since the program started). For help interpreting log files, please check the relevant software manual or contact me if the information is missing. (Hopefully, the log content is mostly self-explanatory but I shall add any explanations I have to send people to the relevant manual’s appendix.)

Error Messages

One of the most important aspects of the log file is to register any error messages. These are marked by an #ERR line header. Hopefully, there will not be any but if there was a problem with the run then these lines should contain the details. To catch these lines separately, errorlog=FILE will output error messages to an additional file.

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