config.txt

# Install directory, in theory the only one variable you could change
export VSPREFIX="$HOME/opt/vapoursynth"
#
# Jobs number, so the hyperthread cores number
export JOBS=$(nproc)
#
#####################################################################
# Read only part
#
my_pkg_config_path="$VSPREFIX/lib/pkgconfig"
python3dotx=$(python3 -V | sed 's/.*\(3\.[0-9]*\).*/python\1/')
vs_site_packages="$VSPREFIX/lib/$python3dotx/site-packages"

if [ $( echo "$PATH" | egrep -Ec "(^|:)$VSPREFIX/bin(:|\$)" ) = "0" ]; then
    export PATH="$VSPREFIX/bin:$PATH"
fi
if [ -z "$PKG_CONFIG_PATH" ]; then
    export PKG_CONFIG_PATH="$my_pkg_config_path"
elif [ $( echo "$PKG_CONFIG_PATH" | grep -Ec "(^|:)$my_pkg_config_path(:|\$)" ) = "0" ]; then
    export PKG_CONFIG_PATH="$my_pkg_config_path:$PKG_CONFIG_PATH"
fi
if [ -z "$LD_LIBRARY_PATH" ]; then
    export LD_LIBRARY_PATH="$VSPREFIX/lib"
elif [ $( echo "$LD_LIBRARY_PATH" | grep -Ec "(^|:)$VSPREFIX/lib(:|\$)" ) = "0" ]; then
    export LD_LIBRARY_PATH="$VSPREFIX/lib:$LD_LIBRARY_PATH"
fi
if [ -z "$PYTHONPATH" ]; then
    export PYTHONPATH="$vs_site_packages"
elif [ $( echo "$PYTHONPATH" | grep -Ec "(^|:)$vs_site_packages(:|\$)" ) = "0" ]; then
    export PYTHONPATH="$vs_site_packages:$PYTHONPATH"
fi