backCmd and restoreCmd allow customizable backup and restore commands to be used instead of tar or zip commands when backing up collection files. If these two parameters are blank, the default commands are used, otherwise the specified command is executed. String substitution is performed before execution to allow specification of input and output directories and collection identification. The string substitution is defined as follows:
${backDir} is replaced by the backup directory specified as the “backDir” configuration parameter.
${collDir} is replaced by the full path name for the collection
${colID} is replaced by the collection ID which is the full name of the backup file.
