TeXmacs is available in Debian GNU/Linux. On a correctly configured Debian system, and with net access, all you have to do to install TeXmacs (as root) is:

    apt-get install texmacs

As usual, you may obtain further information about the TeXmacs package (dependencies on other packages etc.) by executing the command

    apt-cache show texmacs

Alternatively, you may obtain the package information and the package itself from the following web pages:

• Debian package for the stable distribution.
• Debian package for the testing distribution.
• Debian package for the unstable distribution.
• Debian package for the experimental distribution.

If you are running the "unstable" distribution, you can get TeXmacs from "experimental" (by including the corresponding line in your /etc/apt/sources.list) which is rather up-to-date. Versions in "stable", "testing", and "unstable" are way too old. Unfortunately, the package is orphaned. Any volunteers?