W
If we need to find out how many and who are
the users that are currently logged in to the linux system, we can use the 'w'
command.
When we run the 'w' command like ,
[root@vx111a ~]# w
14:07:10 up
1:16, 2 users, load average: 0.25, 0.14, 0.09
USER
TTY FROM LOGIN@
IDLE JCPU PCPU WHAT
root
:0 - 12:52 ?xdm?
3:41 0.08s /usr/bin/gnome-session
root
pts/1
:0.0 12:52 0.00s
0.01s 0.00s w
The Output of the w command prints the
activity on the system currently along with what each user is doing
=> The first line displays the current
time of day
=> How long the system has been running
=> The number of users logged into the
system
=> The load averages. The load average
numbers give the number of jobs in the run queue averaged over 1, 5 and 15
minutes.
The Fields below shows
=>user's login name (USER)
=>the name of the terminal the user is
on (TTY)
=>the host from which the user is logged
in (FROM)
=>the time the user logged on (LOGIN@)
=>the time since the user last typed
anything (IDLE)
=>JCPU is the time used by all processes
attached to the tty. It does not include past background jobs, but does include
currently running background jobs
=>PCPU is the time used by the current
process, named in the "WHAT" field.
=>the name and arguments of the current
process (WAHT)
Uptime
There is some times where we need to find
out how long the system was up and running. Linux provides you various facilities
to find this information. The Uptime information can be obtained from
/proc/uptime like
[root@vx111a ~]# cat /proc/uptime
5272.09 5038.87
and file /var/run/utmp contains information
about who is currently logged on. However, information from /proc or utmp file
is not directly readable by humans .So linux provides us with a command
'uptime' to get information.
[root@vx111a ~]# uptime
14:34:04 up
1:43, 2 users, load average: 0.08, 0.04, 0.01
=>The Current Time : 14:34:04
=>How long the system has been running :
from 1 hour and 43 minutes
=>Users Currently Logged in : 2
=>The load average numbers give the
number of jobs in the run queue averaged over 1, 5 and 15 minutes.
