Portable Vim function to delete old backup files.

delete-old-backups.vim

" I used to run call system('find ~/.vimbackup -mtime +14 -exec gvfs-trash "{}" \;')
" but now have created a more portable version since I work on Windows, Mac, & Linux.

set backup
set nowritebackup
set backupcopy=yes
set backupdir=$HOME/.vimbackup
set directory=$HOME/.vimswap,./

" Timestamp the backups
au VimrcHooks BufWritePre * let &backupext = '~' . localtime()
au VimrcHooks VimLeave * call <SID>DeleteOldBackups()
function! s:DeleteOldBackups() " {{{2
	" Delete backups over 14 days old
	let l:Old = (60 * 60 * 24 * 14)
	let l:BackupFiles = split(glob(&backupdir."/*", 1)."\n".glob(&backupdir."/.[^.]*",1), "\n")
	let l:Now = localtime()

	for l:File in l:BackupFiles
		if (l:Now - getftime(l:File)) > l:Old
			call delete(l:File)
		endif
	endfor
endfunction " }}}