ouroumov@Danaan:~/Desktop$ sudo adduser dummyuser
[sudo] password for ouroumov: 
Adding user `dummyuser' ...
Adding new group `dummyuser' (1003) ...
Adding new user `dummyuser' (1003) with group `dummyuser' ...
Creating home directory `/home/dummyuser' ...
Copying files from `/etc/skel' ...
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully
Changing the user information for dummyuser
Enter the new value, or press ENTER for the default
	Full Name []: 
	Room Number []: 
	Work Phone []: 
	Home Phone []: 
	Other []: 
Is the information correct? [Y/n] 
ouroumov@Danaan:~/Desktop$ sudo addgroup dummyworkgroup
Adding group `dummyworkgroup' (GID 1004) ...
Done.
ouroumov@Danaan:~/Desktop$ sudo adduser ouroumov dummyworkgroup
Adding user `ouroumov' to group `dummyworkgroup' ...
Adding user ouroumov to group dummyworkgroup
Done.
ouroumov@Danaan:~/Desktop$ sudo adduser dummyuser dummyworkgroup
Adding user `dummyuser' to group `dummyworkgroup' ...
Adding user dummyuser to group dummyworkgroup
Done.
ouroumov@Danaan:~/Desktop$ mkdir TRY
ouroumov@Danaan:~/Desktop$ sudo chown :dummyworkgroup TRY/
ouroumov@Danaan:~/Desktop$ ls -al TRY/
total 8
drwxrwxr-x 2 ouroumov dummyworkgroup 4096 Mar 13 01:02 .
drwxr-xr-x 9 ouroumov ouroumov       4096 Mar 13 01:02 ..
ouroumov@Danaan:~/Desktop$ su dummyuser
Password: 
dummyuser@Danaan:/home/ouroumov/Desktop$ cd TRY/
dummyuser@Danaan:/home/ouroumov/Desktop/TRY$ > test
dummyuser@Danaan:/home/ouroumov/Desktop/TRY$ exit
ouroumov@Danaan:~/Desktop$ sudo chown :dummyworkgroup TRY/test
ouroumov@Danaan:~/Desktop$ touch TRY/test 
touch: cannot touch ‘TRY/test’: Permission denied
ouroumov@Danaan:~/Desktop$ ls -alh TRY/test 
-rw-rw-r-- 1 dummyuser dummyworkgroup 0 Mar 13 01:03 TRY/test
ouroumov@Danaan:~/Desktop$ newgrp dummyworkgroup
ouroumov@Danaan:~/Desktop$ touch TRY/test 
ouroumov@Danaan:~/Desktop$