nu/TPU has the ability to create versioned backup files when modified files
are written to disk. nu/TPU backup files have the filename extension of ‘.%99’,
where the 99 represents the version number. The number of versions nu/TPU will
create is determined by the numeric value after the keyword BACKUPS in your
defaults file. The value range is 0 to 99. If the value is 0, no backup files are
created. When no backup value is specified by the user, the nu/TPU default
backup value of 1 is used.
When the backup value is greater than 1 and nu/TPU is attempting to write a
file that already exists on the disk, it will execute the following steps:
1. Starting at .%1, determine the first open backup filename extension up to and
including the backup version number limit.
2. If an open backup filename extension is available, the current file is copied
with a new .%x extension. The original file is then rewritten with the contents
from the nu/TPU edit buffer.
3. If all backup version extension names are utilized, nu/TPU will delete the .%1
file. .%2 will be renamed .%1. nu/TPU will continue to rename the backup
version files until the backup file with the extension number matching the backup
limit is decrement. The original file is then copied to the latest backup file
version number, and the original file is rewritten with the contents of the edit
buffer.
UNIX and DOS files are treated a bit differently during backup. A UNIX
filename, including its extension, is used with an additional .%99 extension for
backup files. A DOS filename, however, loses its extension to the .%99 extension.
Therefore, in DOS file systems where there are multiple files in a directory with
the same filename and different extensions, they will all share the use of
nu/TPU’s backup version numbering process. Thus, writing a file may cause the
removal of a backup for a file with the same filename.
To remove backup files created by nu/TPU, use the following commands:
DOS: del *.%*
UNIX: rm *.%[1-99]
Backup File