Check if String contains Substring in Bash

Check if String contains Substring

To check if a string contains a substring in Bash, use comparison operator == with the substring surrounded by * wildcards.

Syntax

The syntax of expression to check if string str contains substring substr is

$str == *"$substr"*

While using the above expression as a condition in If statement, use double square brackets around the expression.

Example

String contains Substring

In the following script, we take two strings: str and substr, and check if str contains substr. We take values for the strings such that substr is present in str.

Example.sh

str="hello world"
substr="world"
if [[ $str == *"$substr"* ]];
then
    echo "String contains substring."
else
    echo "String does not contain substring."
fi

Output

String contains substring.

String contains Substring

Now, let us take values for the strings such that substr is not present in str.

Example.sh

str="hello world"
substr="good"
if [[ $str == *"$substr"* ]];
then
    echo "String contains substring."
else
    echo "String does not contain substring."
fi

Output

String does not contain substring.

Conclusion

In this Bash Tutorial, we have learnt how to check if a string contains a substring or not in Bash shell.