Linux command: gzip

gzip command is used to reduce the size of given files. This command is so common that you will most likely find it already installed on your Linux distro.

gzip only compresses regular files. Directories, symbolic links etc are not it's food. Files compressed with gzip are often called gzipped files.

gzip also comes with the gunzip, zcat and zless commands for uncompressing and viewing gzipped files.

Let's start gzipping!

Compressing one or more files

To compress one or more files we can simply do like below:

gzip file1 file2 file3

It will compress each file and replace them with compressed versions of them which have a gz suffix:

file1.gz file2.gz file3.gz

Compressing standard input

gzip can also be used via standard input and output:

ls -l /bin | gzip > foo.txt.gz

Uncompressing gzipped files

With the command gunzip we can uncompress them like below:

gunzip file1.gz file2.gz file3.gz

It will replace each compressed file with it's uncompressed version. So you will get the following files:

file1 file2 file3

Compress/Uncompress files recursively in a directory

We can use the -r option to recursively compress each file in a directory:

gzip -r someDir

For a directory containing any gzipped files, we can use gunzip with -r to uncompress all of them recursively with a single command:

gunzip -r someDir

Output to standard output

The -c option can be used by both gzip and gunzip to write output to standard output and keep the original files:

gzip -c some-file > some-file.gz
gunzip -c some-file.gz > some-file-copy

Viewing the gzipped files

When a text file is compressed, it's sometimes handy to view the text without uncompressing and writing it to disk.

To view the contents of a compressed file, there are several ways.

We can simply use the -c option and pipe the output to less to view it:

gunzip -c file1.gz | less

zcat can be used like cat on gzip compressed files. So we can be little more succinct:

zcat file1.gz | less

The command zless allows us view gzipped files in the most clean way:

zless file1.gz

That's for this article. Hope you have learned something useful. For digging deeper see the man page man gzip. Happy gzipping!

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