Question

Use CAT and pipe to wc –l to get a count of the number of entries in ‘foo.txt’

Use SORT and pipe to UNIQ with the –c switch to output a list of duplicate lines preceded by the number of times the line occurs.    Your output should look something like this:        .        .        2 coo       3 foo        1 moo

Use SORT and pipe to UNIQ with the –d switch to output only repeated lines, rather than unique lines.   Your output should look something like:        .        .        8        9        coo        foo

Answer 1

foo.txt looks like this...

1) cat foo.txt | wc -l

The above command first will cat the file foo and will be piped to wc (word count) command with -l option to count number of lines.

2) sort foo.txt | uniq -c

First we will sort the file. Sort command sorts the lines by each and every charecter.

Then we will pipe to unique command which will display all lines once along with their count(using -c option).

3) sort foo.txt | uniq -d

First we will sort the file

Then we will pipe it to uniq command whith -d option which will only display repeated lines.