---
name: "Dpkg::Compression"
section: "3perl"
platform: "linux"
package: "dpkg"
version: "1.23.11-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Dpkg::Compression/3perl"
---

# Dpkg::Compression(3perl)

simple database of available compression methods

## NAME

Dpkg::Compression - simple database of available compression methods

## DESCRIPTION

This modules provides a few public functions and a public regex to interact with the set of supported compression methods.

## FUNCTIONS

- @list = **compression\_get\_list()**

  Returns a list of supported compression methods (sorted alphabetically).

- $bool = compression\_is\_supported($comp)

  Returns a boolean indicating whether the give compression method is known and supported.

- $comp = compression\_guess\_from\_filename($filename)

  Returns the compression method that is likely used on the indicated filename based on its file extension.

- $regex = **compression\_get\_file\_extension\_regex()**

  Returns a regex that matches a file extension of a file compressed with one of the supported compression methods.

- $ext = compression\_get\_file\_extension($comp)

  Return the file extension for the compressor `$comp`.

- $comp = **compression\_get\_default()**

  Return the default compression method. It is "xz" unless **compression\_set\_default()** has been used to change it.

- compression\_set\_default($comp)

  Change the default compression method. Errors out if the given compression method is not supported.

- $level = **compression\_get\_default\_level()**

  Return the global default compression level used when compressing data if it has been set, otherwise the default level for the default compressor.

  It's "9" for "gzip" and "bzip2", "6" for "xz" and "lzma", unless **compression\_set\_default\_level()** has been used to change it.

- compression\_set\_default\_level($level)

  Change the global default compression level. Passing undef as the level will reset it to the global default compressor specific default, otherwise errors out if the level is not valid (see **compression\_is\_valid\_level()**).

- $level = compression\_get\_level($comp)

  Return the compression level used when compressing data with a specific compressor. The value returned is the specific compression level if it has been set, otherwise the global default compression level if it has been set, falling back to the specific default compression level.

- compression\_set\_level($comp, $level)

  Change the compression level for a specific compressor. Passing undef as the level will reset it to the specific default compressor level, otherwise errors out if the level is not valid (see **compression\_is\_valid\_level()**).

- $bool = compression\_is\_valid\_level($level)

  Returns a boolean indicating whether `$level` is a valid compression level (it must be either a number between 1 and 9 or "fast" or "best")

- $threads = **compression\_get\_threads()**

  Return the number of threads to use for compression and decompression.

- compression\_set\_threads($threads)

  Change the threads to use for compression and decompression. Passing `"undef"` or **0** requests to use automatic mode, based on the current CPU cores on the system.

- @exec = compression\_get\_cmdline\_compress($comp)

  Returns a list ready to be passed to **exec()**, its first element is the program name for compression and the following elements are parameters for the program.

  When executed the program will act as a filter between its standard input and its standard output.

- @exec = compression\_get\_cmdline\_decompress($comp)

  Returns a list ready to be passed to **exec()**, its first element is the program name for decompression and the following elements are parameters for the program.

  When executed the program will act as a filter between its standard input and its standard output.

## CHANGES

### Version 3.00 (dpkg 1.23.6)

Remove function: **compression\_get\_property()**.

### Version 2.01 (dpkg 1.21.14)

New functions: **compression\_get\_file\_extension()**, **compression\_get\_level()**, **compression\_set\_level()**, **compression\_get\_cmdline\_compress()**, **compression\_get\_cmdline\_decompress()**, **compression\_get\_threads()** and **compression\_set\_threads()**.

Deprecated functions: **compression\_get\_property()**.

### Version 2.00 (dpkg 1.20.0)

Hide variables: `$default_compression`, `$default_compression_level` and `$compression_re_file_ext`.

### Version 1.02 (dpkg 1.17.2)

New function: **compression\_get\_file\_extension\_regex()**

Deprecated variables: `$default_compression`, `$default_compression_level` and `$compression_re_file_ext`

### Version 1.01 (dpkg 1.16.1)

Default compression level is not global any more, it is per compressor type.

### Version 1.00 (dpkg 1.15.6)

Mark the module as public.