Using only the following UNIX commands: grep, ls, cat and wc, develop a single command line (regular expressions) to perform the task required.

a) Find all the words in a dictionary file that contain all four lower-case characters that appear in the word "unix" (i.e. 'u', 'n', 'i', and 'x') in alphabetical order. For example, influx is such a word, but unfix is not.

(b) Print a single integer that is the number of 6-character words in for example a dictionary file that start with can and end with either a or c. For example, canada is such a word, but canzona, cancel and camera are not.