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

Answer 2

You can try

awk -f a.awk file1 file2

where a.awk is

BEGIN { IGNORECASE=1 }
NR==FNR {
    a[$0]++
    next
}
{
    for (i in a) 
        if (index($0,i)) 
            delete a[i]
}

END {
    for (i in a)
        print i
}