How to check if string has a single colon and that it's in the middle of the string

I am writing a bash script where I need to pass a parameter that follows a simple pattern: string:string.

• Colon must be in the middle of the string
• There must only be exactly one colon in the string

I found this question but it’s looking for the colon at the start of the string. I need the colon to be in the middle of the string and that there’s at most one colon in the string and nothing more. How do I make this check preferrably using regex?

>Solution :

To match any character except ":", use [^:]+ in regex. This regex expression should be able to match one and only one colon.

if [[ $var =~ ^[^:]+:[^:]+$ ]]; then echo "match"; fi