Question

This must be easy for you

Here is file1 (one column)

1
2
3
4
5
6
7
8
9

and here is file2 (two columns)

2 yay
3 ups
4 wow
8 hey

There must be a simple one liner to print out lines in file1 that don´t match to file2

Answer 1

 awk 'NR==FNR{a[$1]++;next;}!($0 in a)' file2 file1

or using join with -v, as @Michael suggested:

join -v1 file1 file2

both will print :

1
5
6
7
9