We have already discussed the gzip command in Linux. For starters, the tool is used to compress or expand files. To uncompress, the command offers a command line option -d, which can be used in the following way:
gzip -d [compressed-file-name]
However, there's an entirely different tool that you can use for uncompressing or expanding archives created by gzip. The tool in question is gunzip. In this article, we will discuss the gunzip command using some easy to understand examples. Please note that all examples/instructions mentioned in the tutorial have been tested on Ubuntu 16.04.
Linux gunzip command
So now we know that compressed files can be restored using either 'gzip -d' or the gunzip command. The basic syntax of gunzip is:
The following Q&A-style examples should give you a better idea of how the tool works:
Q1. How to uncompress archives using gunzip?
This is very simple - just pass the name of the archive file as argument to gunzip.
Q2. How to make gunzip not delete archive file?
As you'd have noticed, the gunzip command deletes the archive file after uncompressing it. However, if you want the archive to stay, you can do that using the -c command line option.
gunzip -c [archive-name] > [outputfile-name]
gunzip -c file1.gz > file1
So you can see that the archive file wasn't deleted in this case.
Q3. How to make gunzip put the uncompressed file in some other directory?
We've already discussed the -c option in the previous Q&A. To make gunzip put the uncompressed file in a directory other than the present working directory, just provide the absolute path after the redirection operator.
gunzip -c [compressed-file] > [/complete/path/to/dest/dir/filename]
Here's an example:
gunzip -c file1.gz > /home/himanshu/file1
The following details - taken from the common manpage of gzip/gunzip - should be beneficial for those who want to know more about the command:
gunzip takes a list of files on its command line and replaces each file
whose name ends with .gz, -gz, .z, -z, or _z (ignoring case) and which
begins with the correct magic number with an uncompressed file without
the original extension. gunzip also recognizes the special extensions
.tgz and .taz as shorthands for .tar.gz and .tar.Z respectively. When
compressing, gzip uses the .tgz extension if necessary instead of trun
cating a file with a .tar extension.
gunzip can currently decompress files created by gzip, zip, compress,
compress -H or pack. The detection of the input format is automatic.
When using the first two formats, gunzip checks a 32 bit CRC. For pack
and gunzip checks the uncompressed length. The standard compress format
was not designed to allow consistency checks. However gunzip is some
times able to detect a bad .Z file. If you get an error when uncom
pressing a .Z file, do not assume that the .Z file is correct simply
because the standard uncompress does not complain. This generally means
that the standard uncompress does not check its input, and happily gen
erates garbage output. The SCO compress -H format (lzh compression
method) does not include a CRC but also allows some consistency checks.
As far as basic usage is concerned, there isn't much of a learning curve associated with Gunzip. We've covered pretty much everything that a beginner needs to learn about this command in order to start using it. For more information, head to its man page.