Check if a user is in a group

Question

I have a server running where I use php to run a bash script to verify certain information of a user. For example, I have a webhosting server set up, and in order to be able to add another domain to their account I want to verify if the user is actually a member of the 'customers' group. What would be the best way to do this?

I have searched google, but all it comes up with is ways to check whether a user or a group exists, so google is not being a big help right now.

Answer 1

Try doing this :

username=ANY_USERNAME if getent group customers | grep -q "\b${username}\b"; then     echo true else     echo false fi 

or

username=ANY_USERNAME if groups $username | grep -q '\bcustomers\b'; then     echo true else     echo false fi 

Answer 2

if id -nG "$USER" | grep -qw "$GROUP"; then     echo $USER belongs to $GROUP else     echo $USER does not belong to $GROUP fi 

Explanation:

1. id -nG $USER shows the group names a user belongs to.
2. grep -qw $GROUP checks silently if $GROUP as a whole word is present in the input.