#include <db.h> int DB_ENV->backup(DB_ENV *dbenv, const char *target, u_int32_t flags);
        The DB_ENV->backup() method performs a hot
        backup of the open environment. All files used by the environment
        are backed up, so long as the normal rules for file placement are
        followed. For information on how files are normally placed relative
        to the environment directory, see
        Berkeley DB File Naming in the Berkeley DB Programmer's Reference Guide.
    
        By default, data directories and the log directory specified
        relative to the home directory will be recreated relative to the
        target directory. If absolute path names are used, then specify
        DB_BACKUP_SINGLE_DIR to the flags
        parameter. 
    
        This method provides the same functionality as the
        db_hotbackup
        utility. However, this method does not perform the housekeeping
        actions performed by the db_hotbackup utility.
        In particular, you may want to run a checkpoint before calling this
        method. To run a checkpoint, use the 
        DB_ENV->txn_checkpoint()
        method. For more information on checkpoints, see
        Checkpoints in the Berkeley DB Programmer's Reference Guide.
    
To back up a single database file contained within the environment, use the DB_ENV->dbbackup() method.
This method's default behavior can be changed by setting backup callbacks. See DB_ENV->set_backup_callbacks() for more information. Additional tuning parameters can also be set using the DB_ENV->set_backup_config() method.
         The DB_ENV->backup() method may only be
         called after the environment handle has been opened.
    
         The DB_ENV->backup() 
            
                  method returns a non-zero error value on failure and 0 on success.
            
            
        
    
                 Identifies the directory in which the back up will be
                 placed. Any subdirectories required to contain the backup
                 must be placed relative to this directory. Note that if
                 the backup callbacks are set, then the value specified to
                 this parameter is passed on to the open_func()
                 callback. If this parameter is NULL, then the target must
                 be specified to the open_func()
                 callback.
             
                 This directory, and any required subdirectories, will be
                 created for you if you specify the
                 DB_CREATE flag on the call to this
                 method. Otherwise, if the target does not exist, this
                 method exits with an ENOENT
                 error return.
             
The flags parameter must be set to 0 or by bitwise inclusively OR'ing together one or more of the values:
                        DB_BACKUP_CLEAN
                    
Before performing the backup, first remove all files from the target backup directory tree.
                        DB_BACKUP_FILES
                    
Back up all ordinary files that might exist in the environment, and the environment's subdirectories.
                        DB_BACKUP_NO_LOGS
                    
                        Back up only the *.db
                        files. Do not backup the log files.
                    
                        DB_BACKUP_SINGLE_DIR
                    
                        Regardless of the directory structure used by the
                        source environment, place all back up files in the
                        single directory identified by the
                        target parameter. Use this
                        option if absolute path names to your environment
                        directory and the files within that directory are
                        required by your application.
                    
                        DB_BACKUP_UPDATE
                    
Perform an incremental back up, instead of a full back up. When this option is specified, only log files are copied to the target directory.
                        DB_CREATE
                    
If the target directory does not exist, create it and any required subdirectories.
                        DB_EXCL
                    
                        Return an EEXIST error if a
                        target backup file already exists.
                    
                        DB_VERB_BACKUP
                    
Run in verbose mode, listing operations as they are completed.
             The DB_ENV->backup() 
            
                 method may fail and return one of the following non-zero errors:
            
            
        
        
                DB_EXCL was specified for the
                flags parameter, and an existing target
                file was discovered when attempting to back up a source
                file.