Backs up/restores Win95 long filenames in DOS.
Copyright © 1995, 2002 D.J. Murdoch
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Also online: an HTML version of the documentation.
DOSLFNBK backs up long filenames and file attributes, to allow you to use
older DOS-based backup and archive programs with Win95/98. It also makes it
possible to recover from a catastrophic disk crash without re-installing
Win95/98 first. Runs on FAT file systems in DOS, Win95/98 or Windows NT.
Microsoft's Windows 95 introduced long filenames (LFNs), and they are mostly
compatible with old software. However, there are some problems. Old backup
programs don't recognize LFNs, so they don't get properly backed up. Worse, the
Win95 backup program didn't support a lot of common backup hardware (e.g.
Colorado Memory Systems tape drives using accelerator cards) and wouldn't run in
DOS mode, so recovery from a catastrophic disk failure could be really
To address this problem, Microsoft put a program called LFNBK on the Win95
CD ROM to back up your LFNs. However, it's very inconvenient to use. It requires
changes to your Control Panel settings before and after use, and it works by
stripping all the LFNs off your disk---so you need to restore them again after
you've done your backup to tape. It will only run after Win95 has booted, so
again you've got big problems after a catastrophic disk failure.
If you've got a program that is completely incompatible with LFNs then you
might want to use LFNBK, but for routine system backups it's too much of a pain.
I wrote DOSLFNBK to address these problems. It runs in any version of DOS
that can see your disk, and can both backup and restore your filenames there.
During backup, it makes no changes to the names, so you can routinely run it
just before a tape backup and not have to undo the damage afterwards. It also
allows partial backups and partial restores.
Nowadays, backup programs are a lot smarter: you may well have a Windows
backup that can do a full restore from DOS. Even if so, you might choose to use
DOSLFNBK for setting up new PCs or in other situations where it's just not
convenient to work in Windows.
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Versions 2.1 to 2.3 of DOSLFNBK fixed serious but fairly rare bugs in 2.0.
Versions 2.4 to 2.7 fix some rare but irritating bugs, and add a few new
features, as described below. Version 2.0 fixed a few minor bugs, and added a
lot of new stuff. The main additions are the following:
- Bug fix for rare directory corruption by DOS
- Bug fixes for very large directories
- Adds support for very large FAT16 disks
- This version adds support for cluster sizes greater than 32K, as you would
get on a FAT16 partitions that are bigger than 2GB.
- Adds /q option for quiet run
- Won't print actions as it does a restore.
- Adds /h option for high level access
- You can now do a backup from a non-FAT disk, as long as Windows is running.
This allows backup of a network drive, for instance.
- Fixes rare bugs on very large disks
Versions 2.0 to 2.3:
- DOSLFNBK became shareware
- I originally wrote DOSLFNBK for my own use, and since I had a lot of help
and suggestions from various people around the net, I released it as
freeware. However, I get a lot of questions and requests for help, and I can
no longer afford the time spent answering those, so the new release is now
shareware. If you use it, you are required to obtain a license.
- Version 1.6 (still available) will remain as
freeware, but I will no longer be offering technical support for it. You're
welcome to use it for free into the indefinite future, but please don't ask
me for help.
- Backup/restore/display of file attributes
- Win95/98 use some combinations of file attributes that confuse older backup
programs. DOSLFNBK can fix the errors caused by improper restore of these
- Check for full restore
- Many programs (e.g. XCOPY) will skip certain files during a backup or
restore operation, leading to bizarre errors. DOSLFNBK now compares the list
of files on disk to the list in its backup file; if any files are missing,
it prints a warning. (It would be nice if it could restore them, but it only
backs up the name!) To help support this option, I've added the /all
option, which will make DOSLFNBK back up every filename on your disk.
- Integrity checks of disk structure
- A lot of old disk utilities (especially defraggers and directory sorters
other than LFNSORT) will mess up your disk. DOSLFNBK
now detects this damage, so that it doesn't make things even worse. It will
optionally attempt repairs, but I strongly recommend using dedicated
software for this.
- Optional overwrite of existing LFNs
- Some versions of DOS (e.g. Hebrew DOS) use LFNs for holding special
non-ASCII characters in 8.3 filenames. DOSLFNBK can't tell the difference
between these LFNs and real ones, so it needs to be able to overwrite names
on demand. Use this carefully: the base name of a file can change even when
you copy the file from one directory to another, so it's often best just to
skip over existing LFNs.
- Better display of special characters
- LFNs store filenames using the 16 bit Unicode character set, but DOS only
knows various 8 bit code pages. DOSLFNBK now does a better job of displaying
filenames using special characters.
- Restore from a different directory
- Sometimes people need to restore filenames to a different directory than
the one where they were backed up. The new /from option allows you
to do this.
- FAT32 support
- The late releases of Win95 and Win98 support partitions on hard disks
larger than 512 Megabytes. They do this by making fairly substantial changes
to the internals of the disk storage, including changing the File Allocation
table from 12 or 16 bit entries to 32 bit entries. DOSLFNBK now supports
- Support for non-IOCTL drives
- Some older tape drives and ramdisks pretend to be a disk drive, but don't
support all the DOS services to provide information about themselves.
DOSLFNBK normally takes a very conservative approach: if it can't get disk
information confirmed from two sources, it won't touch the disk. New in this
release is the option to go ahead based only on partial information. Use
- Automatic operation
- Sometimes you don't want to sit there answering prompts about questionable
situations. DOSLFNBK offers two choices: /auto tells it to
automatically give the safe response (which might be to abort the run, with
an error code); /force tells it that you know what you're doing, and
you want it to go ahead, even if it doesn't look safe.
The following bugs in older versions have been fixed in version 2.7:
- Clusters larger than 32K would cause DOSLFNBK to crash.
- Some prompts were confusing or incorrect.
- /L required the listed directory to exist.
- Versions 2.0 and 2.1 couldn't restore from version 1.x backups.
- Some special characters were displayed improperly.
- Filenames containing special characters were not restored if Windows had
created a new LFN record to hold the special characters.
- If you restored filenames to the directory where your Windows swap file was
located, the swap file directory entry could be corrupted. You should reboot
Windows after using 1.6 for this kind of restore.
- If you have very large directories (more than 2000 short filenames, or some
smaller number of long filenames) a few entries would not be backed up or
restored properly. This could result in corruption of your disk on a
restore. If using version 1.6 for a restore, you should skip over any very
- If you changed some files between the time of the backup and the restore,
and used the /force option to tell DOSLFNBK to restore the LFN without
prompting, versions prior to 2.3 would also restore the old (incorrect) file
- If your root directory was full of erased file entries (as Norton Utilities
leaves it), versions prior to 2.3 would not be able to restore the LFNs.
Fixed by deleting erased file entries if the space is needed.
- Very large disks sometimes caused errors; this is fixed in 2.5.
- Very large directories sometimes caused errors; this is fixed in 2.6.
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DOSLFNBK version 2.7 is available by clicking here.
The freeware version 1.6 is available by clicking here.
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DOSLFNBK is *not* public domain software. Releases up to version 1.6
were freeware, and you may use them at no charge. However, the current release
is shareware. You may use it at no charge for an evaluation period of 30 days
You are free to distribute unmodified copies of the complete DOSLFNBK
package, provided your total charge is no more than $1. The total cost of a
compilation (e.g. a CD ROM) including DOSLFNBK must be no more than $1 per
package in the compilation.
To continue to use DOSLFNBK beyond the 30 day evaluation period, you must
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There is only one kind of license currently available:
DISCONTINUED $20 bonus program registration
DISCONTINUED $45 source code registration
- $10 simple registration
- This registration fee gives you a license to use one copy of DOSLFNBK
indefinitely. If you include an email address when you register I will
notify you of new versions and how to obtain them yourself. I'll also
attempt to answer emailed questions about DOSLFNBK from registered users.
Volume discounts, site licenses and custom versions are available as
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Last updated 21 October 2004