How to install .tgz .txz .tlz and .tbz files

Probably you’ve stumbled on any of those files already. The truth is – this is an ordinary tarball archive as the ones you are already familiar with. It’s the compression method that is different. .tgz uses gzip, .tbz uses BZip, .tlz uses LZW and .txz uses LZMA
If you have a look at the man page of the CLI command installpkg:

13 DESCRIPTION
14        installpkg  installs  single  or  multiple  *.tgz (or .tbz, .tlz, .txz)
15        binary packages designed for use with the Slackware Linux  distribution
16        onto your system.

It’s obvious there is not a single thing that will stop you using this file extension. There was a bug in pkgtool not supporting .txz files but it is fixed long ago. Install/upgrade the new pkgtool from slackware FTP and you are set. The installpkg can be used with 1 smart wildcard to install everything from the .txz, .tgz, .tbz or .tlz file:

installpkg *.t?z

Or if you read carefully Patrick’s upgrade scripts, you will spot the following lines which does upgrading:

for dir in a ap d e f k kde l n t tcl x xap y ; do
  ( cd $dir ; upgradepkg --install-new *.t?z )
done

So regardless what are the packages file name extensions in the installation disc – they will all go installed or upgraded.
The structure of the .txz file is the same as the structure of .tgz package. It is Slackware package with install script in /install and a short blurb explaining the package, some man pages, sample configuration and probably some binaries.
If you want to see what’s inside, use the explodepkg in CLI or the builtin program Ark from KDE/XFCE.

If you are Windows user and are curious what’s inside the .txz file – WinRAR does the job splendidly.