Bash Script to Count Characters in a String

Use echo -n "$string" | wc -m in Bash to count the number of characters in a string, where $string is your input.

Examples

Inputhello

Output5

InputBash scripting!

Output15

Input

Output0

How to Think About It

To count characters in a string, think of the string as a sequence of letters and symbols. You want to find how many characters it has by sending it to a tool that counts characters, ignoring any extra new lines or spaces.

Algorithm

1

Get the input string.

2

Send the string to a command that counts characters without adding extra new lines.

3

Output the count as the result.

Code

bash

#!/bin/bash

string="Hello, world!"
count=$(echo -n "$string" | wc -m)
echo "$count"

Output

13

Dry Run

Let's trace the string "Hello, world!" through the code

1

Set string variable

string="Hello, world!"

2

Count characters

echo -n "Hello, world!" | wc -m # outputs 13

3

Print count

echo "13"

Step	Operation	Value
1	string variable	Hello, world!
2	character count	13
3	output	13

Why This Works

Step 1: Use echo -n

The -n option with echo prints the string without adding a new line, so the count is accurate.

Step 2: Pipe to wc -m

The wc -m command counts the number of characters from the input it receives.

Step 3: Store and print

We save the count in a variable and then print it to show the result.

Alternative Approaches

Using parameter expansion

bash

#!/bin/bash
string="Hello, world!"
count=${#string}
echo "$count"

This method is faster and simpler because it uses Bash's built-in string length feature without calling external commands.

Using printf and wc

bash

#!/bin/bash
string="Hello, world!"
count=$(printf "%s" "$string" | wc -m)
echo "$count"

Using <code>printf</code> avoids issues with echo variations and is more portable.

Complexity: O(n) time, O(1) space

Time Complexity

Counting characters requires looking at each character once, so it takes linear time proportional to the string length.

Space Complexity

The operation uses constant extra space since it only stores the count and the input string.

Which Approach is Fastest?

Using Bash's built-in ${#string} is fastest because it avoids spawning external commands like echo and wc.

Approach	Time	Space	Best For
echo + wc -m	O(n)	O(1)	Simple scripts, portability
Bash ${#string}	O(n)	O(1)	Fastest, pure Bash
printf + wc -m	O(n)	O(1)	Portable and reliable output