Modify the file directory permissions
chmod
chmod u+x b.txt
chmod 777 a.txt
Owner and group modified files
Modify Owner chown beifeng a.txt
Modify your group chgrp beifeng a.txt
Modify owner and group chown root: root a.txt
chmod
chmod u+x b.txt
chmod 777 a.txt
Modify Owner chown beifeng a.txt
Modify your group chgrp beifeng a.txt
Modify owner and group chown root: root a.txt