awk how to remove lines in one file that are found in another file code example

Example: awk how to remove lines in one file that are found in another file

# Example 1
awk 'NR==FNR{a[$0];next} !($0 in a)' file_2 file_1
# This returns all lines in file_1 that are not found in file_2
# See source for more info on how the command works