travis-long-output.sh

#!/bin/bash
set -eu

output="/tmp/$$.log"
idx=0
touch "$output"
NTH_LINE="${NTH_LINE:-100}"
ERROR_LINES="${ERROR_LINES:-200}"
function cleanup () {
	rm -f "$output"
}
trap cleanup EXIT

echo 'travis_fold:start:output-stream'
echo "+ $@ # showing every ${NTH_LINE}th line"
"$@" 2>&1 | tee "$output" | while read line; do
	idx=$((idx+1))
	if [ $(($idx % $NTH_LINE)) -eq 0 ]; then
		echo "... # $line"
	fi
done
status="${PIPESTATUS[0]}"
echo 'travis_fold:end:output-stream'
echo ""

if [ "$status" -eq 0 ]; then
	echo "# Success"
else
	echo "# Exited with status $status. Showing the last $ERROR_LINES lines of output:"
	tail -n "$ERROR_LINES" "$output"
	exit "$status"
fi