There are fairly a number of methods on Linux to get an inventory of the customers logged into the system and see what they’re doing. The instructions described on this article all present very helpful data.
customers
The customers command shows a easy record of logged-in customers. On this instance, one consumer is logged in twice and is, subsequently, listed twice.
$ customers nemo popeye shs shs
Observe that the customers are listed in alphabetical order.
who
The who command gives further data. The login terminal is recognized together with the login date and time. The ultimate subject shows the terminal or the IP deal with of the connecting system.
$ who shs tty2 2022-11-12 10:54 (tty2) nemo pts/0 2022-11-15 11:07 (192.168.0.3) shs pts/5 2022-11-15 10:41 (192.168.0.3) popeye pts/2 2022-11-15 11:12 (192.168.0.3)
w
The w command gives much more data on logged-in customers. The primary line of output reveals the present time, how lengthy the system has been up, the variety of logged-in customers, and the 1-, 5- and 15-minute load averages. This data gives you a fast view of how busy the system is.
The traces following the column headings present usernames, login instances, how lengthy the periods have been idle, the time utilized by all processes related to the consumer’s tty (JCPU), the time utilized by the present course of for the consumer’s terminal (PCPU), and the command being run. If the session is at the moment idle, you’ll merely see the shell that’s in use (e.g., -bash).
The w command gives a fast view of how closely the system is getting used and the place many of the exercise is coming from.
$ w 12:16:09 up 3 days, 15:10, 4 customers, load common: 0.00, 0.01, 0.01 USER TTY LOGIN@ IDLE JCPU PCPU WHAT shs tty2 Sat13 3days 0.05s 0.05s /usr/libexec/gnome-session-bina nemo pts/0 11:07 4:38 0.04s 0.04s -bash shs pts/5 10:41 0.00s 0.10s 0.00s w popeye pts/2 11:12 1:02m 0.02s 0.02s -bash
final
The final command shows an inventory of consumer logins with the newest logins first. To see the newest logins, you should utilize a command like this one:
$ final | head -3 popeye pts/2 192.168.0.3 Tue Nov 15 11:12 nonetheless logged in nemo pts/0 192.168.0.3 Tue Nov 15 11:07 nonetheless logged in shs pts/5 192.168.0.3 Tue Nov 15 10:41 nonetheless logged in
To see how far the at the moment obtainable login data reaches again, pipe the final command’s output to the tail command.
$ final | tail -3 reboot system boot 5.14.10-300.fc35 Mon Jun 6 15:57 - 16:55 (00:58) wtmp begins Mon Jun 6 15:57:30 2022
ps
A ps command just like the one beneath will present an inventory of the processes a consumer is operating. Including the grep -v `whoami` merely omits the command you’ll be operating to create the record. You possibly can simply grep together with your username (e.g., grep -v shs), however the command proven works for anybody.
$ ps -ef | grep nemo | grep -v `whoami` root 124982 787 0 11:07 ? 00:00:00 sshd: nemo [priv] nemo 124990 1 0 11:07 ? 00:00:00 /usr/lib/systemd/systemd --user nemo 124999 124990 0 11:07 ? 00:00:00 (sd-pam) nemo 125018 124982 0 11:07 ? 00:00:00 sshd: nemo@pts/0 nemo 125025 125018 0 11:07 pts/0 00:00:00 -bash
By utilizing grep to pick out course of particulars by the primary subject, you will notice solely that consumer’s processes. The ^nemo argument selects solely the output traces that start with “nemo”.
$ ps -ef | grep ^nemo nemo 124990 1 0 11:07 ? 00:00:00 /usr/lib/systemd/systemd --user nemo 124999 124990 0 11:07 ? 00:00:00 (sd-pam) nemo 125018 124982 0 11:07 ? 00:00:00 sshd: nemo@pts/0 nemo 125025 125018 0 11:07 pts/0 00:00:00 -bash
id
You should utilize the id command to show some further particulars on a consumer. This consists of the consumer’s UID (consumer id), GID (group id), and an inventory of the teams that the consumer is a member of.
$ id nemo uid=1012(nemo) gid=1012(nemo) teams=1012(nemo),900(techs)
finger
You may also get some data on customers with the finger command.
$ finger nemo Login: nemo Title: Nemo the Fish Listing: /residence/nemo Shell: /bin/bash On since Tue Nov 15 11:07 (EST) on pts/0 from 192.168.0.3 1 minute 44 seconds idle No mail. No Plan.
uptime
The uptime command will let you know how lengthy the system has been up since its final reboot and the variety of consumer at the moment logged in. Just like the w command, it additionally gives the system load averages.
$ uptime 12:07:47 up 3 days, 15:01, 4 customers, load common: 0.07, 0.13, 0.06
prime and htop
If you wish to see whether or not a specific consumer’s processes are having an affect on system efficiency, you should utilize a software like prime or htop to find out whether or not any consumer processes are making important use of system assets. Utilizing both of those instruments, urgent the Shift+M keys will kind the output by reminiscence utilization. Utilizing Shift+P will kind the output by processor utilization. The instance beneath reveals nemo as a big consumer of the system CPU and reminiscence, however the system is just not extremely impacted.
prime - 12:41:48 up 3 days, 15:35, 4 customers, load common: 0.14, 0.06, 0.02
Duties: 262 whole, 1 operating, 261 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.8 us, 0.5 sy, 0.0 ni, 98.5 id, 0.2 wa, 0.0 hello, 0.0 si, 0.0 st
MiB Mem : 5926.3 whole, 145.1 free, 2273.7 used, 3507.5 buff/cache
MiB Swap: 5926.0 whole, 5926.0 free, 0.0 used. 3374.3 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3059 root 20 0 259104 29984 8428 S 1.7 0.5 11:11.01 sssd_kcm
134122 nemo 20 0 222648 3976 3524 R 1.3 0.2 0:00.07 loop <===
128996 shs 20 0 225824 4436 3564 R 0.3 0.1 0:00.63 prime
1 root 20 0 172392 17720 11256 S 0.0 0.3 0:03.51 systemd
…
Wrap-up
Instructions for viewing logged-in customers, the processes they’re operating and the way they could affect efficiency will turn out to be useful whether or not you are attempting to get an understanding of how a Linux system is getting used or trying to discover the supply of a efficiency downside.
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