Ratas-2. jacaw-3. saran-remember the wildcard character in string processing * : zero or more character . : any single character [a-z] : any single character from the range [^a-z] : any single character except from the range ls | grep .a[^b]a. means that word having five characters, starting with any character but a should be in second position, third position shouldnt be b and fourth character should be a and any single character in fifth position. grep command is use to process the string with different pattern.