Compress (Unix)

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{{FormatInfo
 
{{FormatInfo
|name=compress
+
|name=compress (Unix)
 
|formattype=electronic
 
|formattype=electronic
 
|subcat=Compression
 
|subcat=Compression
|extensions={{ext|Z}}, {{ext|z}}
+
|extensions={{ext|Z}}
 
|mimetypes={{mimetype|application/x-compress}}
 
|mimetypes={{mimetype|application/x-compress}}
 +
|wikidata={{wikidata|Q29209269}}
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|released=~1984
 
}}
 
}}
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:''This article is about a specific file format. For compression in general, see [[Compression]].''
 +
 
'''compress''' is a Unix command line utility, and a general-purpose compressed file format. Its compression algorithm is based on [[LZW]].
 
'''compress''' is a Unix command line utility, and a general-purpose compressed file format. Its compression algorithm is based on [[LZW]].
  
 
== Identifiers ==
 
== Identifiers ==
The conventional filename extension is a capitalized '''.Z'''. We list lowercase '''.z''' as well, only because filenames are not always case-sensitive.
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The conventional filename extension is a capitalized '''.Z'''.
  
 
== Identification ==
 
== Identification ==
Files begin with bytes <code>1F 9D</code>.
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Files begin with bytes {{magic|1f 9d}}.
  
 
== See also ==
 
== See also ==
* [[pack]] - A compressed file format with a similar filename extension.
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* [[SCO compress LZH]] - variant
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* [[Quasijarus Strong Compression]] - variant
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* [[pack (Unix)]] - predecessor
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* [[compact (Unix)]] - predecessor
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* [[Squash (RISC OS)]]
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Formats that could be considered to be the successors of ''compress'' include [[Freeze/Melt]], and (especially) [[Gzip]].
 +
 
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== The 0x1f compression family ==
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There are several compressed file formats, with similar features, that begin with byte value {{magic|0x1f}} (octal 037; decimal 31). We arbitrarily choose ''compress'' as the representative example, and list the formats here.
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{| class="wikitable"
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! Signature (hex) !! Format
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|-
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| <code>1f 1e</code> || [[pack (Unix)]]
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|-
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| <code>1f 1f</code> || [[pack (Unix)]] - old format
 +
|-
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| <code>1f 8b</code> || [[gzip]]
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|-
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| <code>1f 9d</code> || compress
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|-
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| <code>1f 9e</code> || [[Freeze/Melt]] - old format
 +
|-
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| <code>1f 9f</code> || [[Freeze/Melt]] - new format
 +
|-
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| <code>1f a0</code> || [[SCO compress LZH]]
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|-
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| <code>1f a1</code> || [[Quasijarus Strong Compression]]
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|-
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| <code>1f ff</code> or <code>ff 1f</code> || [[compact (Unix)]]
 +
|}
  
 
== Software ==
 
== Software ==
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* [https://www.gnu.org/software/gzip/ Gzip] can uncompress '''.Z''' files.
 
* [https://www.gnu.org/software/gzip/ Gzip] can uncompress '''.Z''' files.
 
* [[7-Zip]]
 
* [[7-Zip]]
 +
* [https://github.com/vapier/liblzw liblzw]
 
* [http://web.archive.org/web/20130702195528/http://www.willus.com/archive/unixcmds.zip Windows port of Compress utility]
 
* [http://web.archive.org/web/20130702195528/http://www.willus.com/archive/unixcmds.zip Windows port of Compress utility]
 +
* {{Deark}}
  
 
== External links ==
 
== External links ==
 
* [[Wikipedia:Compress|Wikipedia article]]
 
* [[Wikipedia:Compress|Wikipedia article]]
  
{{DISPLAYTITLE:compress}}
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[[Category:File formats with extension .z]]
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[[Category:File formats with case sensitive extensions]]
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{{DISPLAYTITLE:compress (Unix)}}

Revision as of 14:40, 18 September 2020

File Format
Name compress (Unix)
Ontology
Extension(s) .Z
MIME Type(s) application/x-compress
Wikidata ID Q29209269
Released ~1984
This article is about a specific file format. For compression in general, see Compression.

compress is a Unix command line utility, and a general-purpose compressed file format. Its compression algorithm is based on LZW.

Contents

Identifiers

The conventional filename extension is a capitalized .Z.

Identification

Files begin with bytes 1f 9d.

See also

Formats that could be considered to be the successors of compress include Freeze/Melt, and (especially) Gzip.

The 0x1f compression family

There are several compressed file formats, with similar features, that begin with byte value 0x1f (octal 037; decimal 31). We arbitrarily choose compress as the representative example, and list the formats here.

Signature (hex) Format
1f 1e pack (Unix)
1f 1f pack (Unix) - old format
1f 8b gzip
1f 9d compress
1f 9e Freeze/Melt - old format
1f 9f Freeze/Melt - new format
1f a0 SCO compress LZH
1f a1 Quasijarus Strong Compression
1f ff or ff 1f compact (Unix)

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