It is really simple to switch users in Ubuntu or any other Linux distribution using the terminal, iTerm2 or your go to shell program.
All you need to do is to know the username and its account password and you can switch users with su command:
su another_username
You’ll be asked to enter the password of the user you want to switch to.
List all the users on Linux
Let’s say you want to create a sudo user in Linux. Probably, the very first thing to know is how to know what users are in my system. There are several ways you can obtain the list of users in Linux.
Show users in Linux using
less /etc/passwd
This command allows sysops to list the the users that are locally stored in the system. It will give the listing in structured way as:
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
.... /
The structure in the above output goes as:
User name Encrypted password (x represents password is stored) User ID number (UID) User’s group ID number (GID) Full name User’s home directory User’s Login shell (default is bash shell)
The output list will be longer than what is listed above. So many users! Which ones are real? The list shows a lot more users than you expected because it lists all the system users too. To distinguish the normal users from the system users, you can refer to the User identifier (UID) number. Generally, users with UID >=1000 is a normal user and users with UID <1000 are system users.
You’ll also notice that some of the users have ‘nologin’ at the end of their line. This means that these users cannot login to the system. These users are also referred as pseudo-users.
2. View users using getent passwd
getent passwd
This command will deliver a similar output as “less /etc/passwd” however, this one actually queries the GNU Name Service Switch functionality configuration file (located at /etc/nsswitch.conf).
This conf includes passwd, so that’s why it will display very similar but if you use LDAP for authentication it will include that as well.
3. List Linux users with compgen
If you just want to list all the usernames without any additional information, you can use the compgen command with -u option.
compgen -u
The output would be like this:
root daemon bin sys sync games man lp mail news uucp proxy www-data backup list irc gnats
Again not a compete list of the output. More to give you an idea.