Simply Fortran, when starting checks the system's libc version to ensure it is new enough, and it uses a handful of utilities (sort, tr, and head) to do so.  Their dependence on libsystemd is the source of the issue.  We ship a comparatively old version of this library because some of our packaged desktop libraries do indeed need it.  We also institute a shared library loading trick to ensure calls to system programs don't use our packaged libraries, which are undoubtedly incompatible.  However, that "trick" isn't instituted yet when the libc version is checked.

We're working on a fix right now.  The bug is partially our fault because we start redirecting library lookups far too early in the startup process, which is what causes the utilities to try to load our libsystemd.  I think we just need to mix up the startup sequence a bit to protect against this issue.

Note that this bug is not present on Ubuntu earlier than 26.04 (maybe it occurs on 25.10...) or any other Linux distribution that is using GNU coreutils (which is most other popular distros).

When you type simplyfortran in a terminal, what is the output?

Are you using Ubuntu 26.04 in a Wayland session or X11?

What exactly is happening when Simply Fortran doesn't work?

Are you using the ".deb" file from our website?