Maintaining monitor of Linux customers: When do they log in and for a way lengthy?

Getting an concept how usually your customers are logging in and the way a lot time they spend on a Linux server is fairly straightforward with a pair instructions and possibly a script or two.

The Linux command line offers some glorious instruments for figuring out how continuously customers log in and the way a lot time they spend on a system. Pulling info from the /var/log/wtmp file that maintains particulars on consumer logins may be time-consuming, however with a pair straightforward instructions, you possibly can extract plenty of helpful info on consumer logins.

One of many instructions that helps with that is the final command. It offers a listing of consumer logins that may go fairly far again. The output seems like this:

$ final | head -5 | tr -s ” ”
shs pts/0 192.168.0.14 Wed Aug 14 09:44 nonetheless logged in
shs pts/0 192.168.0.14 Wed Aug 14 09:41 – 09:41 (00:00)
shs pts/0 192.168.0.14 Wed Aug 14 09:40 – 09:41 (00:00)
nemo pts/1 192.168.0.18 Wed Aug 14 09:38 nonetheless logged in
shs pts/0 192.168.0.14 Tue Aug 13 06:15 – 18:18 (00:24)

Notice that the tr -s ” ” portion of the command above reduces strings of blanks to single blanks, and on this case, it retains the output proven from being so broad that it could be wrapped round on this internet web page. With out the tr command, that output would seem like this:

$ final | head -5
shs pts/0 192.168.0.14 Wed Aug 14 09:44 nonetheless logged in
shs pts/0 192.168.0.14 Wed Aug 14 09:41 – 09:41 (00:00)
shs pts/0 192.168.0.14 Wed Aug 14 09:40 – 09:41 (00:00)
nemo pts/1 192.168.0.18 Wed Aug 14 09:38 nonetheless logged in
shs pts/0 192.168.0.14 Wed Aug 14 09:15 – 09:40 (00:24)

Whereas it’s straightforward to generate and evaluation login exercise information like these for all customers with the final command or for some specific consumer with a final username command, with out the pipe to go, these instructions will typically lead to a lot of knowledge. On this case, an inventory for all customers would have 908 traces.

$ final | wc -l
908

Counting logins with final

In case you do not want all the login element, you possibly can view consumer login classes as a easy rely of logins for all customers on the system with a command like this:

$ for consumer in `ls /residence`; do echo -ne “$usert”; final $consumer | wc -l; executed
dorothy 21
dory 13
eel 29
jadep 124
jdoe 27
jimp 42
nemo 9
shark 17
shs 423
check 2
waynek 201

The listing above exhibits what number of instances every consumer has logged because the present /var/log/wtmp file was initiated. Discover, nevertheless, that the command to generate it does rely on consumer accounts being arrange within the default /residence listing.

Relying on how a lot knowledge has been collected in your present wtmp file, you might even see plenty of logins or comparatively few. To get just a little extra perception into how related the variety of logins are, you would flip this command right into a script, including a command that exhibits when the primary login within the present file occurred to offer just a little perspective.

#!/bin/bash

echo -n “Logins since ”
who /var/log/wtmp | head -1 | awk ”
echo “=======================”

for consumer in `ls /residence`
do
echo -ne “$usert”
final $consumer | wc -l
executed

Whenever you run the script, the “Logins since” line will let you know the way to interpret the stats proven.

$ ./show_user_logins
Logins since 2018-10-05
=======================
dorothy 21
dory 13
eel 29
jadep 124
jdoe 27
jimp 42
nemo 9
shark 17
shs 423
check 2
waynek 201

collected login time with ac

The ac command offers a report on consumer login time — hours spent logged in. As with the final command, ac reviews on consumer logins because the final rollover of the wtmp file since ac, like final, will get its particulars from /var/log/wtmp. The ac command, nevertheless, offers a a lot totally different view of consumer exercise than the variety of logins. For a single consumer, we would use a command like this one:

$ ac nemo
complete 31.61

This tells us that nemo has spent practically 32 hours logged in. To make use of the command to generate an inventory of the login instances for all customers, you would possibly use a command like this:

$ for consumer in `ls /residence`; do ac $consumer | sed “s/complete/$usert/” ; executed
dorothy 9.12
dory 1.67
eel 4.32

On this command, we’re changing the phrase “complete” in every line with the related username. And, so long as usernames are fewer than eight characters, the output will line up properly. To left justify the output, you possibly can modify that command to this:

$ for consumer in `ls /residence`; do ac $consumer | sed “s/^t//” | sed “s/complete/$usert/” ; executed
dorothy 9.12
dory 1.67
eel 4.32

The primary used of sed in that string of instructions strips off the preliminary tabs.

To show this command right into a script and show the preliminary date for the wtmp file so as to add extra relevance to the hour counts, you would use a script like this:

#!/bin/bash

echo -n “hours on-line since ”
who /var/log/wtmp | head -1 | awk ”
echo “=============================”

for consumer in `ls /residence`
do
ac $consumer | sed “s/^t//” | sed “s/complete/$usert/”
executed

In case you run the script, you may see the hours spent by every consumer over the lifespan of the wtmp file:

$ ./show_user_hours
hours on-line since 2018-10-05
=============================
dorothy 70.34
dory 4.67
eel 17.05
jadep 186.04
jdoe 28.20
jimp 11.49
nemo 11.61
shark 13.04
shs 3563.60
check 1.00
waynek 312.00

The distinction between the consumer exercise ranges on this instance is fairly apparent with one consumer spending just one hour on the system since October and one other dominating the system.

Wrap-up

Reviewing how usually customers log right into a system and what number of hours they spend on-line can each provide you with an summary of how a system is getting used and who’re probably the heaviest customers. In fact, login time doesn’t essentially correspond to how a lot work every consumer is getting executed, but it surely’s probably shut and instructions equivalent to final and ac may help you determine probably the most lively customers.

Extra Linux recommendation: Sandra Henry-Stocker explains easy methods to use the rev command on this 2-Minute Linux Tip video

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