Linux - Delete lines from file 1 in file 2 BIG DATA - linux

Question

have two files:
file1:
a
b
c
d
file2:
a
b
f
c
d
e
output file (file2) should be:
f
e
I want that the lines of file1 should be deleted directly in file2. I want that the output should be not a new file. It should direct deleted in file 2. Of course there can be created a temp file.
I real file two contains more than 300.000 lines. That is the reason why some solution:
comm -13 file1 file2
don't work.

Answer 1

comm needs the input files to be sorted. You can use process substitution for that:
#!/bin/bash
comm -13 <(sort file1) <(sort file2) > tmp_file
mv tmp_file > original_file
Output:
e
f
Alternatively, if you have enough memory, you can use the following awk command which does not need the input to be sorted:
awk 'NR==FNR{a[$0];next} !($0 in a)' file1 file2
Output (preserved sort order):
f
e
Keep in mind that the size of the array a directly depends on the size of file1.
PS: grep -vFf file1 file2 can also be used and the memory requirements are the same as for the awk solution. Given that, I would probably just use grep.