gunzip" -- Command" "

gguunnzziipp [[ --ccffhhLLrrttvvVV ]] [[ _f_i_l_e _._._. ]]

Whenever possible, gunzip replaces each file whose name ends with .z or .Z (and which begins with the correct magic number) with an uncompressed file without the original suffix. gunzip also recognizes the special extensions .tgz and .taz as shorthands for .tar.z or .tar.Z.

gunzip can currently decompress files created by the COHERENT commands gzip or compress, or by the UNIX commands zip or pack. It automatically detects the format by which the file is compressed and applies the correct algorithm to uncompress it.

When uncompressing the formats used by gzip and zip, gunzip checks a 32-bit CRC. For files compressed by pack, gunzip checks the uncompressed length.

The format used by compress was not designed to allow consistency checks. However, gunzip can sometimes detect a corrupted .Z file. If you get an error when uncompressing a .Z file, do not assume that the .Z file is correct simply because the COHERENT command uncompress does not complain. This generally means that most implementations of uncompress do not check their input, and happily generate garbage output.

Command-Line Options

--cc

Write output to standard output, and do not change the original file. If the command line names more than one file, gzip writes to the standard output a sequence of independently compressed members. To obtain better compression, concatenate the files before compressing them.

--ff

force compression or decompression, even if file has multiple links or the corresponding file already exists. Without this option, and when not running in the background, gzip prompts to verify whether it should overwrite an existing file.

--hh

Help: display a screenful of information on how to run this program.

--LL

Display the gzip license.

--rr

Recurse: if a file is a directory, compress or uncompress all files within it.

--tt

Test: check the integrity of a compressed file.

--vv

Verbose: display the name and percentage reduction for each file as it is compressed.

--VV

Display the version of this command, and the options by which it was compiled.

See Also

• commands,
• compress,
• compression,
• gzip,
• unpack
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Diagnostics

A gunzip can issue the following warning messages:

_f_i_l_e:: nnoott iinn ggzziipp ffoorrmmaatt

A file named on the command line was not compressed.

_f_i_l_e:: <> TThhee ccoommpprreesssseedd ffiillee hhaass bbeeeenn ddaammaaggeedd.. IIff tthhee ddaattaa wweerree ccoommpprreesssseedd bbyy tthhee pprrooggrraamm <>ccoommpprreessss<><>,,<> tthheeyy ccaann bbee rreeccoovveerreedd uupp ttoo tthhee ppooiinntt ooff ddaammaaggee bbyy uussiinngg tthhee pprrooggrraamm <>zzccaatt<> ttoo ccoonnccaatteennaattee tthhee ffiillee iinnttoo aannootthheerr ffiillee.. <> <>_f_i_l_e:: ccoommpprreesssseedd wwiitthh _X_X bbiittss,, ccaann oonnllyy hhaannddllee _Y_Y bbiittss

file was compressed by a program that could deal with more bits than the decompress code on this machine. Recompress the file with gzip, which compresses better and uses less memory.

_f_i_l_e:: aallrreeaaddyy hhaass zz ssuuffffiixx ---- nnoo cchhaannggee

file has the suffix .z or .Z; therefore, gunzip assumes that it is compressed already.

_f_i_l_e aallrreeaaddyy eexxiissttss;; ddoo yyoouu wwiisshh ttoo oovveerrwwrriittee ((yy oorr nn))??

Respond `y' if you want the output file to be replaced; `n' if not.

gguunnzziipp:: ccoorrrruupptt iinnppuutt

gunzip detected a SIGSEGV violation, which usually means that the input file has been corrupted.

Notes