[Linux 常見問題] Bash - String contains in Bash

Source From Here 
Question 
Using Bash, I have a string = "My string". How can I test if it contains another string? For example: 

view plaincopy to clipboardprint?

1. if [ $string ?? 'foo' ]; then  
2.   echo "It's there!"  
3. fi  

Where ?? is my unknown operator. Do I use echo and grep? 

How-To 
You can use Marcus's answer (* wildcards) outside a case statement, too, if you use double brackets: 
- test.sh 

view plaincopy to clipboardprint?

1. #!/bin/sh  
2. string="My long string"  
3.   
4. function contain()  
5. {  
6.     echo -e "\t[Info] Check '$1' contains '$2'?"  
7.     if [[ $1 == *"$2"* ]]; then  
8.         echo "Hit!"  
9.     else  
10.         echo "Miss!"  
11.     fi  
12. }  
13.   
14. contain "$string" "My long"  
15. contain "$string" "Missing string"  

Execution result: 

# ./test.sh
[Info] Check 'My long string' contains 'My long'?
Hit!
[Info] Check 'My long string' contains 'Missing string'?
Miss!

Note that spaces in the needle string need to be placed between double quotes, and the * wildcards should be outside the double quotes.