1. id Command
id is a simple command line utility for displaying a real and effective user and group IDs as follows.
$ id ucartz
uid=1000(ucartz) gid=1000(ucartz) groups=1000(ucartz),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),130(sambashare)
2. groups Command
groups command is used to show all the groups a user belongs to like this.
$ groups ucartz
ucartz : ucartz adm cdrom sudo dip plugdev lpadmin sambashare
3. finger Command
finger command is used to search information about a user on Linux. It doesn’t come per-installed on many Linux systems.
To install it on your system, run this command on the terminal.
$ sudo apt install finger #Debian/Ubuntu $ sudo yum install finger #RHEL/CentOS $ sudo dnf install finger #Fedora 22+
It shows a user’s real name; home directory; shell; login: name, time; and so much more as below.
$ finger ucartz
Login: ucartz Name: ucartz
Directory: /home/ucartz Shell: /bin/bash
On since Fri Sep 22 10:39 (IST) on tty8 from :0
2 hours 1 minute idle
No mail.
No Plan.
4. getent Command
getent is a command line utility for fetching entries from Name Service Switch (NSS) libraries from a specific system database.
To get a user’s account details, use the passwd database and the username as follows.
$ getent passwd ucartz
ucartz:x:1000:1000:ucartz,,,:/home/ucartz:/bin/bash
5. grep Command
grep command is a powerful pattern searching tool available on most if not all Linus systems. You can use it to find information about a specific user from the system accounts file: /etc/passwd as shown below.
$ grep -i ucartz /etc/passwd
ucartz:x:1000:1000:ucartz,,,:/home/ucartz:/bin/bash
6. lslogins Command
lslogins command shows information about known users in the system, the -u flag only displays user accounts.
$ lslogins -u
UID USER PROC PWD-LOCK PWD-DENY LAST-LOGIN GECOS
0 root 144 root
1000 ucartz 70 10:39:07 ucartz,,,
1001 arun 0
7. users Command
users command shows the usernames of all users currently logged on the system like so.
$ users
ucartz
aaron
8. who Command
who command is used to display users who are logged on the system, including the terminals they are connecting from.
$ who -u
ucartz tty8 2017-09-22 10:39 02:09 2067 (:0)
9. w Command
w command shows all users who are logged on the system and what they are doing.
$ w
12:46:54 up 2:10, 1 user, load average: 0.34, 0.44, 0.57
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
ucartz tty8 :0 10:39 2:10m 4:43 0.46s cinnamon-sessio
10. last or lastb commands
last/lastb commands displays a list of last logged in users on the system.
$ last OR $ last -a #show hostname on the last column
ucartz tty8 Fri Sep 22 10:39 gone - no logout :0 reboot system boot Fri Sep 22 10:36 still running 4.4.0-21-generic ucartz tty8 Thu Sep 21 10:44 - down (06:56) :0 reboot system boot Thu Sep 21 10:42 - 17:40 (06:58) 4.4.0-21-generic ucartz tty8 Wed Sep 20 10:19 - down (06:50) :0 reboot system boot Wed Sep 20 10:17 - 17:10 (06:52) 4.4.0-21-generic ucartz pts/14 Tue Sep 19 15:15 - 15:16 (00:00) tmux(14160).%146 ucartz pts/13 Tue Sep 19 15:15 - 15:16 (00:00) tmux(14160).%145 ...
To show all the users who were present at a specified time, use the -p option as follows.
$ last -ap now
ucartz tty8 Fri Sep 22 10:39 gone - no logout :0
reboot system boot Fri Sep 22 10:36 still running 4.4.0-21-generic
wtmp begins Fri Sep 1 16:23:02 2017
11. lastlog Command
lastlog command is used to find the details of a recent login of all users or of a given user as follows.
$ lastlog OR $ lastlog -u ucartz #show lastlog records for specific user ucartz
Username Port From Latest root **Never logged in** kernoops **Never logged in** pulse **Never logged in** rtkit **Never logged in** saned **Never logged in** usbmux **Never logged in** mdm **Never logged in** ucartz pts/1 127.0.0.1 Fri Jan 6 16:50:22 +0530 2017 ..
That’s it!
