Since the Batch Launcher is a stand-alone Java program, its "current" or "base" directory is determined by the location from which the Java VM is launched. This in turn determines where any outputs produced by batch programs will be written to. If required, this base location can be specified by setting the batch.base.dir property when running the Batch Launcher, i.e.
build runbatch -Dbatch.base.dir=<Directory>
Where <Directory> is the new location required.
The default location from which the VM is launched is %SERVER_DIR%\buildlogs. Where SERVER_DIR is your platform environment variable (e.g., %SERVER_DIR% on Windows).
Output from the Batch Launcher is captured in the output directory via the Ant <record> task in files that are named BatchLauncheryyyyMMddHHmmss.log; where " yyyy " maps to the year, " MM " to the month, " dd " to the day, " HH " to the hour, " mm " to the minute, and " ss " to the second. Thus, each output log file is named based on when the Ant runbatch target is invoked and batch jobs that start at the same time will write to the same file.