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

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
}