file1.txt&file2.txt的交集==============
cat file1.txt file2.txt | sort | uniq -d > file3.txt
file1.txt相对file2.txt的差集===========
cat file1.txt file3.txt | sort | uniq -u >file.txt
file2.txt相对file1.txt的差集===========
cat file2.txt file3.txt | sort | uniq -u >file.txt
file1.txt&file2.txt对称比较的差============
cat file1.txt file2.txt | sort | uniq -u > temp.txt