The File::BackupCopy module provides functions for creating backup copies of
files.  Two backup schemes are supported: simple and numbered backups.  In
simple (or single) backup scheme, only one backup copy is maintained for the
given file.  Its name is created by appending a single tilde character to the
original file name.  In numbered backup scheme, arbitrary number of backup
copies can be created.  The name of each backup copy is created by suffixing
the original file name with '.~N~', where N is a decimal number starting with
1.  Additionally, the automatic backup name scheme is implemented.  In this
naming scheme, numbered backups are created if at least one numbered backup
copy already exists and simple backups are created otherwise.