[root@ob2 mytmp]# find -type f -name "*.html" -or -name "*.txt"
./02.html
./aa.html
./03.html
./01.html
./aa2.txt
[root@ob2 mytmp]# find -type f -name "*.html" -and -name "*.txt"
[root@ob2 mytmp]# find -type f -name "*.html" -or -name "*.txt"
./02.html
./aa.html
./03.html
./01.html
./aa2.txt
[root@ob2 mytmp]# find -type f -name "*.html" -and -name "*.txt"