Set group

chown [options] user[:group] file...

sudo chown www-data:www-data /var/www/html -R
sudo chown deploy app/
sudo chown :staff shared/

Note Requires root/sudo for files you do not own. user:group changes both at once. :group (with colon, no user) changes only the group. -R applies recursively. Be careful with -R on directories containing symlinks; use --no-dereference to avoid following them.

chgrp [options] group file...

sudo chgrp developers /opt/shared-repo -R

Note Equivalent to chown :group. -R applies recursively. You can only change to a group you belong to unless you are root.