directory permissions adding user in a group

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http://askubuntu.com – I added a user using useradd useradd -g upperdevs myuser But when I do an id check I didn't see the upperdevs group. id myuser #uid=1000(myuser) gid=1000(myuser) groups=1000(myuser),27(sudo) Probably this was the issue why I can't write to certain_dir, by doing ls -l: drwxrwxr-x 2 root upperdevs 4096 Sep 8 13:35 certain_dir Anything I'm doing wrong? (HowTos)