Check if all lines from one file are present somewhere in another file

Question

I used file1 as a source of data for file2 and now I need to make sure that every single line of text from file1 occurs somewhere

Answer 1

if grep -Fqvf file2 file1; then
    echo $"There are lines in file1 that don’t occur in file2."
fi

Grep options mean:

-F, --fixed-strings       PATTERN is a set of newline-separated fixed strings
-f, --file=FILE           obtain PATTERN from FILE
-v, --invert-match        select non-matching lines
-q, --quiet, --silent     suppress all normal output