Bash Script to Count Words in a String

Use echo "$string" | wc -w in Bash to count the number of words in a string.

Examples

Inputhello world

Output2

Input this is a test string

Output5

Input

Output0

How to Think About It

To count words in a string, think of splitting the string by spaces and counting each piece. The wc -w command counts words from input, so we send the string to it using echo and a pipe.

Algorithm

1

Get the input string.

2

Send the string to the word count command using a pipe.

3

Count the words and return the result.

Code

bash

#!/bin/bash
string="$1"
word_count=$(echo "$string" | wc -w)
echo "$word_count"

Output

2

Dry Run

Let's trace the string 'hello world' through the code

1

Assign input string

string='hello world'

2

Count words

echo 'hello world' | wc -w outputs 2

3

Print result

echo 2

Step	Action	Value
1	string variable	hello world
2	word count command output	2
3	final output	2

Why This Works

Step 1: Use echo to output the string

The echo command prints the string so it can be processed by other commands.

Step 2: Pipe output to wc -w

The pipe | sends the string to wc -w, which counts the words.

Step 3: Store and print the count

The word count is saved in a variable and printed to show the result.

Alternative Approaches

Using set and $#

bash

#!/bin/bash
string="$1"
set -- $string
echo $#

This splits the string into positional parameters and counts them with <code>$#</code>. It is fast but changes shell parameters.

Using array and length

bash

#!/bin/bash
string="$1"
read -ra words <<< "$string"
echo "${#words[@]}"

This reads words into an array and counts elements. It is clean and safe for scripts.

Complexity: O(n) time, O(n) space

Time Complexity

The script processes each character once to split words, so time grows linearly with string length.

Space Complexity

Extra space is used to hold the string and split words temporarily, proportional to input size.

Which Approach is Fastest?

Using set -- $string is fastest but modifies shell state; wc -w is simple and safe; arrays offer clarity.

Approach	Time	Space	Best For
echo + wc -w	O(n)	O(n)	Simple and safe word count
set and $# (positional params)	O(n)	O(n)	Fast but changes shell parameters
array and length	O(n)	O(n)	Clear and safe in scripts