Word Frequency

Write a bash script to calculate the frequency of each word in a text file words.txt.

For simplicity sake, you may assume:

• words.txt contains only lowercase characters and space ' ' characters.

• Each word must consist of lowercase characters only.

• Words are separated by one or more whitespace characters.

For example, assume that words.txt has the following content:

the day is sunny the the
the sunny is is

Your script should output the following, sorted by descending frequency:

the 4
is 3
sunny 2
day 1

**Note:

** Don’t worry about handling ties, it is guaranteed that each word’s frequency count is unique.

Solving method：

# Read from the file words.txt and output the word frequency list to stdout.
cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -rn | awk '{print $2" "$1}'