UNDELETE--Notes
◄Examples► ◄Syntax►
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UNDELETE──Notes
CAUTION: Once you delete a file from your disk, you may not be able
retrieve it. Although the UNDELETE command can recover deleted
files, it can do so with certainty only if no other files have
been created or changed on the disk. If you accidentally delete a
file that you want to keep, stop what you are doing and
immediately use the UNDELETE command to retrieve the file.
Levels of protection
MS-DOS provides three levels of protection against accidental file
deletion──Delete Sentry, Delete Tracker, and standard.
Delete Sentry provides the highest level of protection. Delete Sentry
requires a small amount of memory and disk space. The next level of
protection is Delete Tracker, which requires the same amount of memory as
Delete Sentry, but minimal disk space. The lowest level of protection,
standard, requires neither memory nor disk space, but still allows you to
recover deleted files, provided that their location on the disk has not been
taken by other files.
For more details, see the notes that follow about each level of protection.
Delete Sentry
Delete Sentry provides the highest level of protection to ensure that you
can recover deleted files. This level of protection creates a hidden
directory named SENTRY. When you delete a file, UNDELETE moves the file from
its current location to the SENTRY directory without changing the record of
the file's location in the file allocation table (FAT). If you undelete the
file, MS-DOS moves the file back to its original location.
The size of the SENTRY directory and its files is limited to approximately 7
percent of your hard disk space. If you delete a file and the directory and
its files exceed this limit, UNDELETE purges the oldest files until enough
space has been freed to accommodate the newly deleted file.
In addition to the disk space needed for the SENTRY directory, Delete Sentry
requires 13.5K of memory for the memory-resident portion of the UNDELETE
program.
Delete Tracker
Delete Tracker provides an intermediate level of protection. It uses a
hidden file named PCTRACKER.DEL to record the location of deleted files.
When you delete a file, MS-DOS changes the file allocation table (FAT) to
indicate that the location of the file is now available for another file.
You can recover the deleted file provided that another file has not been
placed in that location. If another file has been placed there, you may be
able to partially recover the deleted file.
Delete Tracker requires 13.5K of memory for the memory-resident portion of
the UNDELETE program and a minimal amount of disk space for the
PCTRACKER.DEL file.
Standard
The standard level of protection is automatically available when you switch
on your computer. Of the three levels of guarding against accidental file
deletion, it provides the lowest level of protection. However, it does not
require you to load a memory-resident program. It also has the advantage of
requiring neither memory nor disk space.
Using this level of protection, you can recover a deleted file, provided
MS-DOS has not placed another file in the deleted file's location. If a file
has been placed there, you may be unable to recover all or part of the
deleted file.
Method used to recover files
Use any one of the following switches: /DOS, /DT, or /DS. If you do not
specify a switch, UNDELETE uses Delete Sentry, if it is available. If Delete
Sentry is not available, UNDELETE uses the Delete Tracker file, if
available. If a deletion-tracking file is not available, UNDELETE attempts
to recover files by using MS-DOS.
CAUTION: UNDELETE cannot restore a directory that has been removed, and it
cannot retrieve a file if you have removed the directory that
contained the file. If the directory was an immediate subdirectory
of the root directory, you may be able to retrieve the directory
and its files if you first use the UNFORMAT command to restore the
directory and then use UNDELETE to retrieve the files. You must
use caution because you can lose data if you use UNFORMAT
incorrectly. Usually, UNFORMAT can restore only immediate
subdirectories of the root directory. However, when you use
UNFORMAT to recover an accidentally formatted disk, UNFORMAT
recovers all root-level files and subdirectory names.
The UNDELETE.INI file
UNDELETE uses the UNDELETE.INI file to define values when UNDELETE is loaded
into memory. If the file does not exist when you load UNDELETE into memory,
UNDELETE creates an UNDELETE.INI file that contains the following values:
♦ Use the Delete Sentry method of file tracking on the current drive.
♦ Save all files except *.TMP, *.VM?, *.WOA, *.SWP, *.SPL, *.RMG, *.IMG,
*.THM, and *.DOV files.
♦ Do not save files that have the archive bit set.
♦ Purge files after 7 days.
♦ Restrict the amount of disk space available for deleted files to 20
percent of total disk space.
The UNDELETE.INI file has five sections: [sentry.drives], [sentry.files],
[mirror.drives], [configuration], and [defaults].
The [sentry.drives] section specifies the drives protected by the Delete
Sentry method, if used.
The [sentry.files] section specifies the files protected from deletion using
either Delete Tracker or Delete Sentry. A hypen (-) before a filename
indicates that the file is not saved. The default values defined in the
[sentry.files] section are as follows:
[sentry.files]
*.* -*.TMP -*.VM? -*.WOA -*.SWP -*.SPL -*.RMG -*.IMG -*.THM -*.DOV
The [mirror.drives] section specifies the drives protected by the Delete
Tracker method, if used.
The [configuration] section defines the following values:
♦ Whether files with the archive bit set are protected. If files with the
archive bit set are not protected (the default value), the entry is as
follows:
archive=FALSE
A TRUE value saves files with the archive bit set.
♦ The number of days files are saved. The following entry defines the
default value:
days=7
♦ The amount of total disk space reserved for deleted files. The following
entry defines the default value:
percentage=20
The [defaults] section specifies the method of file tracking. The following
defines the default Delete Sentry method:
[defaults]
d.sentry=TRUE
d.tracker=FALSE
Changing the method of file protection
You can use only one method of file protection at a time. If you want to
change the method, carry out the following procedure:
1 Unload the memory-resident portion of the Undelete program by typing the
following at the command prompt:
undelete /u
2 Enable the new level of protection and reload the memory-resident portion
of the Undelete program. For example, to enable the Delete Sentry level
of protection on your current drive, type the following at the command
prompt:
undelete /s
Drives protected
The Undelete program protects all drives specified in the UNDELETE.INI file,
regardless of the drives you specify when you start the program. For
example, suppose your UNDELETE.INI file contains the following entry:
[sentry.drives]
C=
D=
The following command enables the Delete Sentry level of protection on both
drives C and D:
undelete /sc
To enable protection only on drive C, you would do the following:
1 Using any text editor, open your UNDELETE.INI file.
2 Delete the following line from the [sentry.drives] section of the file:
D=
3 Save changes you made to the file.
4 Exit your text editor.
5 Enable Delete Sentry protection by typing the following at the command
line:
undelete /sc
Network drives and delete protection
To protect files on a network drive from accidental deletion, you must
enable the Delete Sentry level of protection and have read, write, create,
and delete file access in the drive's root directory.
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