Append to File using Bash

1

echo "Line you want to append" >> ~/ideas.md

The command here that ammends the line to the file is >>. If you place any string block before this operator and point it to a file, it will get appended.

1

tail -f something.log | grep important >> ./important.log

Note: if you use the operator > instead or accidentally, it will overwrite the whole file it is point to.