求救：shell script/awk question

I have one .csv file “file1” of 3 columns. And another file “file2” of 4 columns. I want to compare the first 3 columns of these two files and print out lines in file 2 where the first 3 columns don’t exist in file 1. This is my code: awk -F”,” ‘NR==NFR{a[$1,$2,$3]=$1$2$3;next} {if(!a[$1,$3,$3]=$1$2$3) {print $0}}’ file1 file2 If the files are delimited by space, the script works. It just doesn’t work for csv. similarly, egrep works fine if the delimiter of the files is space, but not csv files. egrep -vf file1 file2 哪位大拿有高招？試了無數次，惱火的很。