functions.sh

set -eu

function hide_output {
	# This function hides the output of a command unless the command fails
	# and returns a non-zero exit code.

	# Get a temporary file.
	OUTPUT=$(tempfile)

	# Execute command, redirecting stderr/stdout to the temporary file. Since we
	# check the return code ourselves, disable 'set -e' temporarily.
	set +e
	$@ &> $OUTPUT
	E=$?
	set -e

	# If the command failed, show the output that was captured in the temporary file.
	if [ $E != 0 ]; then
		# Something failed.
		echo
		echo FAILED: $@
		echo -----------------------------------------
		cat $OUTPUT
		echo -----------------------------------------
		exit $E
	fi

	# Remove temporary file.
	rm -f $OUTPUT
}

function apt_get_quiet {
	# all of that and only show it if there is a problem (i.e. if apt_get returns a failure exit status).
	DEBIAN_FRONTEND=noninteractive hide_output apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confnew" "$@"
}