In file1, delete lines from file2?

Question

linux

As in file1 containing lines like mail: first name: last name: age, delete those lines that are contained in file2 where just mail is indicated
.
cat file2; do sed -i -e "/$a/d" file1; done

Answer 1

How to delete the lines in file1 containing lines of the form mail: first name: last name: age that are contained in file2 where just mail is indicated

grep -f file2.txt -v file1.txt >output.txt

Answer 2

join -v 1 -t: <(sort файл1) <(sort файл2)
the output will be lexicographically sorted.
man join
man sort

Answer 3

swears forever for similar errors
join: /dev/fd/62:1474: no sort: 010203.:[email protected]