DAT3 - Fallout DAT Tool

Fallout and Troika .dat management CLI.

Crossplatform, static Rust re-implementation of DAT2, with minor differences. Also supports Arcanum and The Temple of Elemental Evil .dat archives.

• Usage
• Differences from DAT2
• Verifying a release
• Building

Usage

dat3

Fallout and Troika .dat management CLI

Usage: dat3 [OPTIONS] <COMMAND>

Commands:
  l     List files in a DAT archive
  x     Extract files preserving directory structure
  e     Extract files flat (no subdirectories)
  a     Add files to a DAT archive
  d     Delete files from a DAT archive
  help  Print this message or the help of the given subcommand(s)

Options:
      --case-sensitive  Match, list, extract and add entry names exactly as stored. Without it, names match regardless of case and are listed, extracted and added in lowercase
  -h, --help            Print help
  -V, --version         Print version

Extract all files

dat3 x master.dat

Extract all files into directory

dat3 x master.dat -o ./extracted/

Extract specific files

# Can use forward or backward slashes
dat3 x master.dat art/critters/HMMAXX.FRM scripts\generic.int

# Extract with glob pattern (quote to prevent shell expansion)
dat3 x master.dat 'art/critters/*.frm'

Extract without directory structure (flat)

dat3 e master.dat -o ./files/

List files in a DAT archive

# List all files
dat3 l master.dat

# List specific files. Can use forward or backward slashes. Output always shows OS-native slash.
dat3 l master.dat art/critters/vault.frm text\english\quotes.txt

# List with glob pattern (quote to prevent shell expansion)
dat3 l master.dat 'art/critters/*.frm'

# List files from response file
dat3 l master.dat @files_to_list.txt

# List as JSON, for another program to parse
dat3 l master.dat --json

--json prints one entry object per line, and always uses forward slashes so the output is identical on every platform:

[
  {"name": "art/critters/vault.frm", "size": 4096, "packed_size": 1180, "compressed": true},
  {"name": "text/english/quotes.txt", "size": 84, "packed_size": 84, "compressed": false}
]

The names it prints are the names x, e, and d accept back. A pattern that matches nothing is still an error: the array on stdout is empty, the unmatched name goes to stderr, and the exit status is non-zero.

Tolerating names that are not in the archive

By default l, x and e fail when a requested name or glob matches nothing, and extract nothing. --ignore-missing turns that failure into a warning:

# Lists and extracts whatever is there, warns about the rest, exits 0
dat3 l master.dat --ignore-missing art/critters/vault.frm no/such/file.txt
dat3 x master.dat --ignore-missing -o ./extracted/ @files.txt

The unmatched names still go to stderr, so a script can log them. Useful when one file list is run against several archives and only some of them hold each file. Every name missing is not an error either - nothing is extracted and the exit status is still 0.

Letter case in entry names

The games look files up regardless of case, so by default dat3 does too:

• names and globs given to l, x, e and d match regardless of case
• l and l --json list names in lowercase
• x and e create lowercase files and directories
• a stores new entries in lowercase, and replaces an entry that differs only in case

Entries already in an archive keep their stored case until they are added again.

An archive can hold names that differ only in case, such as README.TXT and readme.txt. dat3 keeps those apart: they are listed and extracted in their stored case, a name matching one of them selects all of them, and every command that opens the archive prints a warning naming them.

--case-sensitive turns all of this off, for any command: names match exactly, and are listed, extracted and added as stored or given.

dat3 x master.dat --case-sensitive -o ./extracted/

Response file support

# Create a file listing files to process
echo "art/critters/vault.frm" > files.txt
echo "text\english\quotes.txt" >> files.txt
echo "scripts/generic.int" >> files.txt

# Use with any command (mutually exclusive with explicit file lists)
dat3 l master.dat @files.txt
dat3 x master.dat @files.txt -o extracted/
dat3 e master.dat @files.txt -o flat/
dat3 a master.dat @files.txt
dat3 d master.dat @files.txt

Add files to a DAT archive

# Add single file
dat3 a master.dat myfile.txt

# Add files relative to another directory
dat3 a master.dat -C patch000 file.txt  # patch000/file.txt
Adding: file.txt  # Added to archive root

# Add directory (automatically recursive)
dat3 a master.dat myfolder/

# Add with max compression level
dat3 a master.dat largefile.txt -c 9

# Add to specific directory in archive
dat3 a master.dat myfile.txt -t "art/graphics"

# Choose the format for a new archive (dat1, dat2, arcanum, toee; default dat2)
dat3 a newarchive.dat myfiles/ --format dat1
dat3 a newarchive.dat myfiles/ --format arcanum
dat3 a newarchive.dat myfiles/ --format toee

# Add files from response file
dat3 a master.dat @files_to_add.txt

Add-path normalization

• ./ and .\ prefixes are removed before storing paths in the archive
• absolute source paths have only their filesystem root/prefix stripped
• the first real directory name is preserved
• a -C DIR ... resolves add operands inside DIR and stores paths relative to DIR
• a -C DIR ... rejects ./.. components and paths that resolve outside DIR

Examples:

dat3 a master.dat ./patch000/file.txt
# stores as patch000/file.txt

dat3 a master.dat ./patch000/*
# stores as patch000/...

dat3 a master.dat /tmp/patch000/file.txt
# stores as tmp/patch000/file.txt

Default format via .bgforge.yml

When a creates a new archive and no --format is given, an optional .bgforge.yml in the current directory picks the default:

dat3:
  default_format: arcanum

Supported values: dat1, dat2, arcanum, toee. An unrecognized value prints a warning and dat2 is used. An explicit --format always wins, and existing archives always keep their format.

Delete files from archive

# Delete single file (cross-platform paths supported)
dat3 d master.dat text/english/quotes.txt

# Delete multiple files
dat3 d master.dat file1.txt art\critters\vault.frm

# Delete with glob pattern (quote to prevent shell expansion)
dat3 d master.dat 'art/critters/*.frm'

# Delete files from response file
dat3 d master.dat @files_to_delete.txt

Differences from DAT2

• Directories are always processed recursively.
• Shrink (k command) not implemented.
• Flat extraction is a separate command, e.
• DAT1 compression (LZSS) not implemented, only decompression. Fallout 1 style .dat files are thus created without compression.
• Glob patterns (*, ?, [...]) supported for list/extract/delete.
• Names are matched, listed, extracted and added in lowercase unless --case-sensitive is given (see Letter case in entry names).

Verifying a release

Every release ships a SHA256SUMS file covering its binaries. Download it alongside the assets and check them:

sha256sum -c SHA256SUMS

Only the files you downloaded need to be present; sha256sum reports the rest as missing.

Building

Requirements

• Rust 1.87 or newer
• Target-specific toolchains (install as needed)
• ./install-tools.sh for the pinned tooling, including Zig, which the aarch64 target needs: mimalloc is C, and no aarch64-musl C compiler is packaged for common distros
• Node 24 or newer, to run the integration suite (./test.sh): its helpers under tests/ are TypeScript, run by Node's own type stripping. npm ci && npm run typecheck typechecks them. Neither is needed to build dat3

Build

./build.sh

Builds are static.

Binaries will be at:

target/x86_64-unknown-linux-musl/release/dat3
target/aarch64-unknown-linux-musl/release/dat3
target/x86_64-pc-windows-gnu/release/dat3.exe
target/i686-pc-windows-gnu/release/dat3.exe
target/wasm32-wasip1/release/dat3.wasm