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.

 

 

cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -r | awk '{print $2" "$1}'
tr -s: 使用指定字符串替換出現一次或者連續出現的目標字符串（把一個或多個連續空格用換行符代替）

sort: 將單詞從小到大排序

uniq -c: uniq用來對連續出現的行去重，-c參數爲計數

sort -r: -r 倒序排列

awk '{ print $2, $1 }': 格式化輸出，將每一行的內容用空格分隔成若干部分，$i爲第i個部分。