How can I add new user to already existing group in console mode ?[Solved]

[Azano]

Hi!
Like in the title, I want to add a user to already existing group.
In fact it´s seems that i already did this because i used a command "adduser --ingroup groupA user2” and when I look to the passwd i see that "user2(this is the user that i want to add)" is assignated to the groupA.
But the problem appear when i want to log in to the user2, because when I type the password, Linux don´t do nothing. I think that is some problem with permition, and i tried to change the owner of the document groupA(with chown) but it doesn´t gave me any any results, so here is my question:
Do i do something wrong or i need to use other command?

I hope i explained this well and i hope you can help me guys.

P.S.
Sorry for my english.

[deadflowr]

I just run

sudo adduser username groupname

Look here for more

man adduser

[Lars Noodén]

chown and many other system utilities won't say anything when they run correctly. It is expected that they just work and not say anything unless there was an error. Can you verify that you changed the group of the document using ls -hl?

If both the user and the group already exist, you can add the user to the group with gpasswd

sudo gpasswd --user user2 groupa

The membership in the new group won't take effect until that user logs out and then logs back in again.

[clearski]

Assuming that the group and username are already created, I do it with:

sudo usermod -aG <groupname> <username>

then I check with

cat /etc/group | grep <groupname>

I usually find the <username> as a part of the <groupname> in the /etc/group

[Azano]

Problem solved, i used the option from @deadflowr. Thanks guys.