sage-system-python

#!/usr/bin/env bash

# Run the system python.
#
# This is primarily for use by the build toolchain so that it can continue
# using the system Python rather than Sage's Python, preventing conflicts
# that might otherwise occur, particularly in parallel builds.
#
# See https://trac.sagemath.org/ticket/18438

if [ -z "$SAGE_ORIG_PATH" ]; then
    # If not we're running from within sage-env just set the existing path
    SAGE_ORIG_PATH="$PATH"
fi

# In particular, it is invoked by "bootstrap -d" for sage-download-file,
# i.e., before a configure run, and by "sage-spkg", also for sage-download-file.
# So it needs to find a python that has the urllib module.
# For example, on Debian buster, the python3-minimal package does NOT provide it.
#
# See https://trac.sagemath.org/ticket/29090

PYTHONS="python2 python3 python3.8 python3.7 python2.7 python python3.6 python2"
for PY in $PYTHONS; do
    PYTHON="$(PATH="$SAGE_ORIG_PATH" command -v $PY)"
    if [[ -n "$PYTHON" ]]; then
        if "$PYTHON" -c 'import urllib'; then
            exec "$PYTHON" "$@"
        fi
    fi
done
echo >&2 "$0: error: none of $PYTHONS is a suitable Python with urllib"
exit 1