Danke. Durch den Begriff wrapper kann ich weiter googlen
#less /etc/python-exec/python-exec.conf
# python-exec global preference configuration
#
# This file specifies global Python preference for python-exec. It
# determines which implementations will be used when wrapped Python
# scripts or generic Python wrappers (such as /usr/bin/python) are
# started with no implementation override (EPYTHON).
#
# The global configuration can be overriden for each wrapped script
# in /etc/python-exec/<script-name>.conf. If this override exists,
# the global configuration is not used at all.
#
# The preference file should list Python implementations, one per line,
# in EPYTHON-format (e.g. python3.5), in order of preference. The most
# preferred implementation should be listed first. The program will use
# the most preferred implementation that is supported by it.
#
# If none of the listed implementations are supported, python-exec will
# attempt to use the remaining supported implementations in default
# order.
#
# A specific implementation can be disabled by preceding it with
# a hyphen (-). In this case, the implementation will never be used.
# If no other implementation is supported by the program, it will fail
# to start.
#
# Note: this file can be modified by calls to 'eselect python'.
python3.6
