Shell脚本终止程序，但导致不写入输出文件

Question

I am wanting to run a program in the background that collects some performance data and then run an application in the foreground. When the foreground application finishes it detects this and the closes the application in the background. The issue is that when the background application closes without first closing the file, I'm assuming, the output of the file remains empty. Is there a way to constantly write the output file so that if the background application unexpectedly closes the output is preserved?

Here is my shell script:

./background_application -o=output.csv &
background_pid=$!

./foreground_application
ps -a | grep foreground_application
if pgrep foreground_application > /dev/null
then
     result=1
else
     result=0
fi

while [ result -ne 0 ]
do
     if pgrep RPx > /dev/null
     then
          result=1
     else
          result=0
     fi
     sleep 10
done
kill $background_pid
echo "Finished"

I have access to the source code for the background application written in C++ it is a basic loop and runs fflush(outputfile) every loop iteration.

Answer 1

This would be shorter:

./background_application -o=output.csv &
background_pid=$!
./foreground_application
cp output.csv output_last_look.csv
kill $background_pid
echo "Finished"