# compiling PETSc included in the ET fails if "python" executable is missing

Issue #2565 new
Roland Haas created an issue

The copy of PETSc included in the ET’s ExternalLibraries uses a shebang “/usr/bin/env python” in some of the scripts used during compilation. This fails on modern Debian and Ubuntu (even LTS 20.04) systems that no longer provide a “python” executable unless one of the pyhon-is-pythonX packages is installed (for X \in {2,3}).

This should be fixed until the next release either by updating the included tarbal or patching the scripts to refer to either python2 or python3 (whichever one they actually need). Requiring a Debian package to be installed is not really an option, even though I suspect that the Debian / Ubuntu policy violates Python’s installation instructions.

At least the tarball currently included (petsc-3.12.5.tar.gz) expects “python” to be “python2”. Sicne that version is from around 29-Mar-2020 a newer version may help.