As
a system administrator, you may want to know who is on the system at any give
point in time. You may also want to know what they are doing. In this article
let us review 4 different methods to identify who is on your Linux system.
1. Get the running processes of logged-in user using w
w
command is
used to show logged-in user names and what they are doing. The information will
be read from /var/run/utmp file. The output of the w command contains the
following columns:
§ Name
of the user
§ User’s
machine number or tty number
§ Remote
machine address
§ User’s
Login time
§ Idle
time (not usable time)
§ Time
used by all processes attached to the tty (JCPU time)
§ Time
used by the current process (PCPU time)
§ Command
currently getting executed by the users.
2. Get the user name and process of logged in user using who and users command
who
command is
used to get the list of the usernames who are currently logged in. Output of
the who command contains the following columns: user name, tty number, date and
time, machine address.
$ who
ramesh pts/0 2009-03-28 22:57 (dev-db-server)
jason pts/1 2009-03-28 23:01 (dev-db-server)
john pts/2 2009-03-28 23:04 (dev-db-server)
Users Command
users
command is
used to print the user name who are all currently logged in the current host.
It is one of the command don’t have any option other than help and version. If
the user using, ‘n’ number of terminals, the user name will shown in ‘n’ number
of time in the output.
$ users
john jason ramesh
3. Get the username you are currently logged in using whoami
whoami command is used to print the loggedin
user name.
$ whoami
john
4. Get the user login history at any time
last
command will
give login history for a specific username. If we don’t give any argument for
this command, it will list login history for all users. By default this
information will read from /var/log/wtmp file. The output of this command
contains the following columns:
§ User
name
§ Tty
device number
§ Login
date and time
§ Logout
time
§ Total
working time
$ last jason
jason pts/0 dev-db-server Fri Mar 27 22:57 still logged in
jason pts/0 dev-db-server Fri Mar 27 22:09 - 22:54 (00:45)
jason pts/0 dev-db-server Wed Mar 25 19:58 - 22:26 (02:28)
jason pts/1 dev-db-server Mon Mar 16 20:10 - 21:44 (01:33)
jason pts/0 192.168.201.11 Fri Mar 13 08:35 - 16:46 (08:11)
jason pts/1 192.168.201.12 Thu Mar 12 09:03 - 09:19 (00:15)
jason pts/0 dev-db-server Wed Mar 11 20:11 - 20:50 (00:39
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