Gateway Log File

Use date and time specifiers in log file name

You can use date and time specifiers in the log file name. These specifiers then get populated with relevant date/time information during the logging process. By default this is evaluated against the Gateway start time, but is evaluated against the roll time if this is used.

See Time Zones and Time Formats for a list of time specifiers.

Note: It is possible that using these specifiers will allow a number of log files to build up on disk. See Archive log files for more information.

For example, if you start up a Gateway on the 3rd of Jan 2013 at 09:30, the command containing -log GatewayLogExample-%Y-%m-%d-%H-%M.log, the generated log file would be GatewayLogExample-2013-01-03-09-30.log.

Roll over due to maximum file size

To stop log files from getting excessively large, Gateway log files roll over when they reach a certain size limit.

Upon hitting this size limit, the active log file is archived. See Archive log files.

By default, the log file rolls over when the log file reaches 10485760 bytes (or 10 MB). However, it can be configured to rollover after up to a maximum of 2147483647 bytes (2 GB) with a 32-bit Gateway. To do this, either:

• Set the environment variable MAX_LOG_FILE_SIZE_MB to an appropriate amount in MB.
• Set operatingEnvironment > maxLogFileSizeMb to an appropriate amount in MB.

Archive log files

When the log file reaches its maximum size, or a roll time has been reached, a new log file is opened. When the Gateway starts a new log file, any existing file with the same name is renamed to <filename>.old.

To prevent a large number of log files being retained, only the latest .old file is kept. If <filename>.old already exists it is overwritten. Consequently, using a simple filename results in there only ever being two log files: the current log, and the old log.

Using time specifiers in the filename usually results in a new filename that does not already exist, particularly if the full date is used. However, this may cause the number of files on disk to continue to increase.

Not including the whole date increases the number of possibilities, such as just including the day or day of the month, which creates a weekly or monthly rotation of files. .old files may still be generated during a day if the maximum size is reached, therefore it may be advisable to increase the maximum size if the files on disk is limited by a rotation system.

A UNIX script can be called to move log files. The archive script can be used to:

• Move or copy .old files into an archive elsewhere.
• Prevent a large number of date/time based files building up by removing the older ones if the full date is specified.

The UNIX script can be specified using:

• operatingEnvironment > logArchiveScript
• LOG_ARCHIVE_SCRIPT environment variable.

Note: Using operatingEnvironment > logArchiveScript overrides LOG_ARCHIVE_SCRIPT (if set).

The script is run when the Gateway switches to using a new log file. The name of the old log file is passed to the script, which is either:

• <filename>.old, if the log file name did not change.
• The old log <filename>, if the log file name did change.

If the log file name is changed to a file that already exists, the existing file is moved to <filename>.old. That file is not passed to the archive script.