User Information

 

User Information

1. who It is used to get information about currently logged in user on to system. If you don't provide any option or arguments, the command displays the following information for each logged-in user.

   1. Login name of the user
   2. User terminal
   3. Date & Time of login
   4. Remote host name of the user

   $ who
   sudheer :0 2019-08-04 01:21 (:0)

2. whoami: It display the system’s username

   $ whoami
   sudheer

3. id: It display the user identification(the real and effective user and group IDs) information

   $ id
   uid=1000(sj) gid=1000(sj) groups=1000(sj),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),120(lpadmin),131(lxd),132(sambashare)

4. groups: This command is used to display all the groups for which the user belongs to.

   $ group
   sj: sj, adm, cdrom, sudo, dip, plugdev, lpadmin, lxd, sambashare

5. finger: Used to check the information of any currently logged in users. i.e, It displays users login time, tty (name), idle time, home directory, shell name etc.

   $ finger
   Login     Name       Tty      Idle  Login Time   Office     Office Phone
   sj        sj        *:0             Aug 28 01:27 (:0)

   This may not be available by default in many linux machines. In this case, you need to install it manually.

   $ sudo apt install finger

6. users: Displays usernames of all users currently logged on the system.

   $ users
   sj

7. grep: It is a powerful pattern searching tool to find information about a specific user from the system accounts file: /etc/passwd.

   $ grep -i sj /etc/passwd
   sj:x:1000:1000:sj,,,:/home/sj:/bin/bash

8. W Command: It(W) is a command-line utility that displays information about currently logged in users and what each user is doing.

   w [OPTIONS] [USER]
   
   Example:
   w
    18:45:04 up  2:09,  1 user,  load average: 0.09, 0.07, 0.02
   USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
   sj       :0       :0               01:27   ?xdm?   1:14   0.01s /usr/lib/gdm3/g

9. last or lastb: Displays a list of last logged in users on the system. You can pass user names to display their login and hostname details.

   last [options] [username...] [tty...]
   
   Example:
   
   last
   sj       :0           :0               Fri Aug 28 01:27    gone - no logout
   reboot   system boot  5.4.0-29-generic Fri Aug 28 01:27   still running
   sj       :0           :0               Wed Jul 29 11:46 - crash (29+13:40)
   reboot   system boot  5.4.0-29-generic Wed Jul 29 11:45   still running
   sj       :0           :0               Thu May 14 21:04 - crash (75+14:41)
   reboot   system boot  5.4.0-29-generic Thu May 14 21:03   still running
   
   wtmp begins Thu May 14 21:03:56 2020

10. lastlog: The lastlog command is used to find the details of a recent login of all users or of a given user.

    $ lastlog
    
    Username         Port     From             Latest
    root                                       **Never logged in**
    daemon                                     **Never logged in**
    bin                                        **Never logged in**
    sys                                        **Never logged in**
    sync                                       **Never logged in**
    games                                      **Never logged in**
    man                                        **Never logged in**
    lp                                         **Never logged in**
    mail                                       **Never logged in**
    news                                       **Never logged in**