Main Content


Method of disk file handling for logged data


LogToDiskMode can be set to 'append', 'overwrite' or 'index'. If LogToDiskMode is set to 'append', then data for a logged session is added to any data that already exists in the log file when logging is started using the start command. If LogToDiskMode is set to 'overwrite', then the log file is overwritten each time start is called. If LogToDiskMode is set to 'index', then a different disk file is created each time start is called, according to the following rules:

  1. The first log file name attempted is specified by the initial value of LogFileName.

  2. If the attempted file name exists, then a numeric identifier is added to the value of LogFileName. For example, if LogFileName is initially specified as 'groupRlog.olf', then groupRlog.olf is the first attempted file, groupRlog01.olf is the second file name, and so on. If the LogFileName already contains numbers as the last characters in the file name, then that number is incremented to create the new log file name. For example, if the LogFileName is specified as 'groupLog003.olf', then the next file name would be 'groupLog004.olf'.

  3. The actual file name used is the first file name that does not exist. In this way, each consecutive logging operation is written to a different file, and no previous data is lost.

Separate dagroup objects are logged to separate files. If two dagroup objects have the same value for LogFileName, then attempting to log data from both objects simultaneously will result in the second object failing during the start operation.



Read-only while logging

Applies to


Data type

character vector


[ 'append' | {'index'} | 'overwrite' ]

See Also