According to the manual ARCHIVE should do it, although there are some caveats. This is the usage notes from the manual:
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Usage notes
This command can be used to collect a complete set of log files up to a known point. The log files can then be used to update a standby database.
This command can only be executed when the invoking application or shell does not have a database connection to the specified database. This prevents a user from executing the command with uncommitted transactions. As such, the ARCHIVE LOG command will not forcibly commit the user's incomplete transactions. If the invoking application or shell already has a database connection to the specified database, the command will terminate and return an error. If another application has transactions in progress with the specified database when this command is executed, there will be a slight performance degradation since the command flushes the log buffer to disk. Any other transactions attempting to write log records to the buffer will have to wait until the flush is complete.
If used in a partitioned database environment, a subset of database partitions can be specified by using a database partition number clause. If the database partition number clause is not specified, the default behavior for this command is to close and archive the active log on all database partitions.
Using this command will use up a portion of the active log space due to the truncation of the active log file. The active log space will resume its previous size when the truncated log becomes inactive. Frequent use of this command can drastically reduce the amount of the active log space available for transactions.
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Note that the issuer of this command cannot have a connection. It also implies that although it will truncate the log file, it will not archive until it becomes inactive.
Andy