Problem
You are experiencing performance problems with your Oracle database server (Linux or Solaris). To help diagnose the issues, you first want to view all users currently logged on to the box.
Solution
Use the who command to display the users logged on to a box:
$ who
The output consists of four columns: users logged on, terminal name, time they logged on, and location where they logged on. Here’s a typical listing of the who command:
ptownshend pts/1 Jun 15 14:17 (vpn-229-150-36-51.com)
rdaltrey pts/2 Aug 10 22:11 (122.120.44.181)
jentwistle pts/3 Aug 16 03:14 (111.155.23.114)
kmoon pts/4 Sep 4 01:23 (10.6.77.121)
kjones pts/6 Dec 4 06:66 (101.120.23.171)
You can also use the who command with the am i option to display your current user information:
$ who am i
oracle pts/2 Aug 4 15:30 (vpn-109-150-32-93.brdstn.com)
Tip You can also use whoami or the id -un to display information about your current user. Contrast this with the who am i command, which always shows which user you initially used to log on to a server. For example, if you su to a different user, whoami displays your current user status, whereas who am i shows which user you originally logged on to the server as.
How It Works
The who command is important for listing a snapshot of users logged on to the server. An alternative to the who command is the w utility. This simply titled but powerful tool is an extension to the who command. The output of the w command is like a combination of the listings from the who, uptime, and ps -a commands. This example uses the w command to eavesdrop on who is logged on to the system and what they are doing:
$ w
17:59:54 up 9 days, 5:37, 4 users, load average: 0.00, 0.00, 0.00
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
enehcd pts/1 vpn-128-156-33-6 12:32 5:46 0.12s 0.12s -bash
evork pts/2 vpn-129-156-33-6 15:22 34:14 0.01s 0.01s -chmod
aznoga pts/3 vpn-129-156-32-6 17:22 55:24 0.03s 0.01s -sleep
wroot pts/4 vpn-129-150-150- 17:48 0.00s 0.02s 0.00s w
The first line of the w output is similar to that produced by the uptime command; it shows current time, how long the system has been up, number of users, and system load averages. After the header line, it displays users logged on, from where and what time, how long they’ve been idle, current job CPU (JCPU), foreground process CPU (PCPU), and what command the user is running.
To specifically look at one user, specify the process name as an option. The following command looks at all oracle accounts logged on to the server:
$ w oracle
The following output indicates that there are two active oracle users on the box:
14:14:58 up 130 days, 21:52, 2 users, load average: 0.00, 0.00, 0.00
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
oracle pts/1 63-231-82-100.hl 13:10 0.00s 0.03s 0.00s w oracle
oracle pts/2 63-231-82-100.hl 14:14 6.00s 0.01s 0.01s -bash
If a user has logged on twice to a server (as in the previous output), you can use the tty command to identify a session. Log on to one of the oracle sessions; here is the tty command and its output:
$ tty
/dev/pts/1
You can also use the finger command to display information about users logged on to a server. If you don’t provide the finger command with a username, it will display all users on a system:
$ finger
Login Name Tty Idle Login Time Office Office Phone
oracle pts/0 Jun 20 13:29 (br-ea-fw-nat.surg.com)
oracle pts/1 2 Jun 20 13:29 (br-ea-fw-nat.surg.com)
The pinky command is a lightweight version of the finger command. If no users are specified as a parameter, all users logged on will display:
$ pinky
Login Name TTY Idle When Where
oracle pts/0 Jun 20 13:29 br-ea-fw-nat.surg.com
oracle pts/1 00:03 Jun 20 13:29 br-ea-fw-nat.surg.com
