---
name: "unsnappy"
section: "1"
platform: "linux"
package: "snappy-tools"
version: "1-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/snappy"
---

# unsnappy(1)

Snappy compression and decompression with and without framing

Part of [snappy(1)](/snappy/1.md).

## NAME

**snappy**, **unsnappy** – Snappy compression and decompression with and without framing

## SYNOPSIS

**snappy** \[**-f**\] \[*file*\] \> *snappy.sn*\|*.sz*

**snappy** **-d** \[**-i**\] \[*file*\]

**unsnappy** \[**-i**\] \[*file*\]

## DESCRIPTION

Without **-d**, compresses *file* (standard input stream if "**-**", the default) with Snappy to the standard output stream, then assesses the compression ratio achieved to the standard error stream.\
 With **-f**, the Snappy framing format is produced.

When run as **unsnappy**, or with **-d**, decompresses *file* (likewise) from Snappy, or the Snappy framing format (detected automatically), to the standard output stream.\
 With **-i**, decompression and framing errors are ignored and processing continues.

As a format limitation, if *file* isn't seekable when producing or decompressing unframed Snappy streams, it will be read into memory in its entirety.

## EXIT STATUS

- **1**

  If a decompression error (invalid or truncated Snappy block) or a framing error (Stream identifier (**0xFF**) frame invalid, unknown reserved unskippable chunk (\[**0x02**, **0x7F**\]) frame encountered, checksum mismatch).

- **2**

  On an I/O error.

- **3**

  When compressing without **-f** and *file* is larger than 4GiB. (Output unaffected, but see BUGS.)

## DIAGNOSTICS

After compressing,

```
data: 2048576 -> 1099105 (53.65%)
```

means that the *file* *data* was 2048576 bytes, which were compressed down to 1099105 bytes, and the output is thus 53.65% the size.

## SEE ALSO

*The Snappy homepage:* **https://google.github.io/snappy/**

## CONFORMING TO

The framed format, with MIME type ‘application/x-snappy-framed’, version 2013-10-25: *Snappy framing format description:* **https://github.com/google/snappy/blob/main/framing\_format.txt**.

The unframed format, as described in *Snappy compressed format description:* **https://github.com/google/snappy/blob/main/format\_description.txt**, as provided by the upstream library “libsnappy”.

## BUGS

The largest representable unframed stream is of size 4GiB-1B (= 4·1024·1024·1024B-1B = 4294967295B). Above this size the length stored in the header becomes mangled, so the stream may be semantically correct but will produce an incorrect (short) output when decompressing. **snappy** warns about this and exits **3**.

On 32-bit systems it is impossible to produce unframed streams from files larger than 4GiB-1B at all due to an API limitation (EXIT STATUS **2**). On 32-bit systems the output size and compression ratio will be misrepresented if compression produces an unframed output larger than 4GiB-1B. It is also impossible to decompress such files there.

Supposedly, compressors which produce checksums with inverted byte order exist in the wild.