Can multiple .gz files be combined such that they extract into a single file? [duplicate]

Question

Lets say that I have 3 file: 1.txt, 2.txt and 3.txt which have all be gzipped. I'm aware that gzip allows multiple files to be combined using cat:

cat 1.gz 2.gz 3.gz > 123.gz

However when 123.gz is extracted it will produce the original 3 files.

Is it possible to combine the three archives in a way that the individual files within the archive will be combined into a single file as well?

Answer 1

Surprisingly, this is actually possible.

The GNU zip man page states: multiple compressed files can be concatenated. In this case, gunzip will extract all members at once.

Example:

You can build the zip like this:

echo 1 > 1.txt ; echo 2 > 2.txt; echo 3 > 3.txt;
gzip 1.txt; gzip 2.txt; gzip 3.txt;
cat 1.txt.gz 2.txt.gz 3.txt.gz > all.gz

Then extract it:

gunzip -c all.gz > all.txt

The contents of all.txt should now be:

1
2
3

Which is the same as:

cat 1.txt 2.txt 3.txt

And - as you requested - "gunzip will extract all members at once".