As a Linux administrator, you need to keep track of all users' activities. When something goes wrong in the server, you can analyze and investigate the users' activities, and try to find the root cause of the problem. There are many ways to monitor users in Linux. In this guide, we are going to talk about GNU accounting utilities that can be used to monitor the user activity in Linux.
What are Accounting utilities?
The Accounting utilities provides the useful information about system usage, such as connections, programs executed, and utilization of system resources in Linux. These accounting utilities can be installed using psacct or acct package.
The psacct or acct are same. In RPM-based systems, it is available as psacct, and in DEB-based systems, it is available as acct.
What is the use of psacct or acct utilities? You might wonder. Generally, the user's command line history details will be stored in .bash_history file in their $HOME directory. Some users might try to edit, modify or delete the history.
However, the accounting utilities will still be able to retrieve the users activities even though they cleared their command line history completely. Because, all process accounting files are owned by root user, and the normal users can't edit them.
Install psacct or acct in Linux
The psacct/acct utilities are packaged for popular Linux distributions.
To install psacct in Alpine Linux, run:
$ sudo apk add psacct
To install acct in Arch Linux and its variants like EndeavourOS and Manjaro Linux, run:
$ sudo pacman -S acct
On Fedora, RHEL, and its clones like CentOS, AlmaLinux and Rocky Linux, run the following command to install psacct:
$ sudo dnf install psacct
In RHEL 6 and older versions, you should use yum instead of dnf to install psacct.
$ sudo yum install psacct
On Debian, Ubuntu, Linux Mint, install acct using command:
$ sudo apt install acct
To install acct on openSUSE, run:
$ sudo zypper install acct
Start psacct/acct service
To enable and start the psacct service, run:
$ sudo systemctl enable psacct
$ sudo systemctl start psacct
To check if psacct service is loaded and active, run:
$ sudo systemctl status psacct
On DEB-based systems, the acct service will be automatically started after installing it.
You can verify whether acct service is started or not using command:
$ sudo systemctl status acct
Sample output:
● acct.service - Kernel process accounting
Loaded: loaded (/lib/systemd/system/acct.service; enabled; vendor preset: enabled)
Active: active (exited) since Thu 2022-10-13 16:06:35 IST; 28s ago
Docs: man:accton(8)
Process: 3241 ExecStart=/usr/sbin/accton /var/log/account/pacct (code=exited, status=0/SUCCESS)
Main PID: 3241 (code=exited, status=0/SUCCESS)
CPU: 879us
Oct 13 16:06:35 ubuntu2204 systemd[1]: Starting Kernel process accounting...
Oct 13 16:06:35 ubuntu2204 accton[3241]: Turning on process accounting, file set to '/var/log/account/pacct'.
Oct 13 16:06:35 ubuntu2204 systemd[1]: Finished Kernel process accounting.Download - Free eBook: "Nagios Monitoring Handbook"
Monitor User Activity in Linux using psacct or acct
The psacct (Process accounting) package contains following useful utilities to monitor the user and process activities.
- ac - Displays statistics about how long users have been logged on.
- lastcomm - Displays information about previously executed commands.
- accton - Turns process accounting on or off.
- dump-acct - Transforms the output file from the accton format to a human-readable format.
- dump-utmp - Prints utmp files in human-readable format.
- sa - Summarizes information about previously executed commands.
Let us learn how to monitor the activities of Linux users by using each utility with examples.
1. The ac command examples
The ac utility will display the report of connect time in hours. It can tell you how long a user or group of users were connected to the system.
1.1. Display total connect time of all users
$ ac
This command displays the total connect time of all users in hours.
total 52.91
1.2. Show total connect of all users by day-wise
You can sort this result by day-wise by using -d flag as shown below.
$ ac -d
Sample output:
May 11 total 4.29 May 13 total 3.23 May 14 total 7.66 May 15 total 8.97 May 16 total 0.52 May 20 total 4.09 May 24 total 1.32 Jun 9 total 15.18 Jun 10 total 2.97 Jun 22 total 2.61 Jul 19 total 1.95 Today total 0.29
1.3. Get total connect time by user-wise
Also, you can display how long each user was connected with the system with -p flag.
$ ac -p
Sample output:
ostechnix 52.85 root 0.51 total 53.36
1.4. Print total connect time of a specific user
And also, you can display the individual user's total login time as well.
$ ac ostechnix
Sample output:
total 52.95
1.5. View total connect time of a certain user by day-wise
To display individual user's login time by day-wise, run:
$ ac -d ostechnix
Sample output:
May 11 total 4.29 May 13 total 3.23 May 14 total 7.66 May 15 total 8.97 May 16 total 0.01 May 20 total 4.09 May 24 total 1.32 Jun 9 total 15.18 Jun 10 total 2.97 Jun 22 total 2.61 Jul 19 total 1.95 Today total 0.68
For more details, refer the man pages.
$ man ac
2. The lastcomm command examples
The lastcomm utility displays the list of previously executed commands. The most recent executed commands will be listed first.
2.1. Display previously executed commands
$ lastcomm
Sample output:
systemd-hostnam S root __ 0.06 secs Thu Oct 13 17:21 systemd-localed S root __ 0.06 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 awk ostechni pts/1 0.00 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 uname ostechni pts/1 0.00 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 sed ostechni pts/1 0.00 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 grep ostechni pts/1 0.00 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 grep ostechni pts/1 0.00 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 bash F ostechni pts/1 0.00 secs Thu Oct 13 17:22 [...]
2.2. Print last executed commands of a specific user
The above command displays all user's commands. You can display the previously executed commands by a particular user using command:
$ lastcomm ostechnix
Sample output:
less ostechni pts/1 0.00 secs Thu Oct 13 17:26 lastcomm ostechni pts/1 0.00 secs Thu Oct 13 17:26 lastcomm ostechni pts/1 0.00 secs Thu Oct 13 17:26 lastcomm ostechni pts/1 0.00 secs Thu Oct 13 17:26 gdbus X ostechni __ 0.00 secs Thu Oct 13 17:24 lastcomm ostechni pts/1 0.00 secs Thu Oct 13 17:24 ac ostechni pts/1 0.00 secs Thu Oct 13 17:24 update-notifier F ostechni __ 0.00 secs Thu Oct 13 17:23 apport-checkrep ostechni __ 0.06 secs Thu Oct 13 17:23 apport-checkrep ostechni __ 0.05 secs Thu Oct 13 17:23 systemctl ostechni __ 0.00 secs Thu Oct 13 17:23 apt-check ostechni __ 0.81 secs Thu Oct 13 17:23 dpkg ostechni __ 0.00 secs Thu Oct 13 17:23 ischroot ostechni __ 0.00 secs Thu Oct 13 17:23 dpkg ostechni __ 0.00 secs Thu Oct 13 17:23 [...]
2.3. Print total number of command execution
Also, you can view how many times a particular command has been executed.
$ lastcomm apt
Sample output:
apt S root pts/2 0.70 secs Thu Oct 13 16:06 apt F root pts/2 0.00 secs Thu Oct 13 16:06 apt F root pts/2 0.00 secs Thu Oct 13 16:06
As you see in the above output, the apt command has been executed three times by root user.
For more details, refer the man pages.
$ man lastcomm
3. The sa command examples
The sa utility will summarize the information about previously executed commands.
3.1. Print summary of all commands
$ sa
Sample output:
1522 1598.63re 0.23cp 0avio 32712k
139 570.90re 0.05cp 0avio 36877k ***other*
38 163.63re 0.05cp 0avio 111445k gdbus
3 0.05re 0.04cp 0avio 12015k apt-check
27 264.27re 0.02cp 0avio 0k kworker/dying*
2 51.87re 0.01cp 0avio 5310464k Docker Desktop
5 0.03re 0.01cp 0avio 785k snap-confine
8 59.48re 0.01cp 0avio 85838k gmain
5 103.94re 0.01cp 0avio 112720k dconf worker
24 3.38re 0.00cp 0avio 2937k systemd-udevd*
7 0.01re 0.00cp 0avio 36208k 5
3 1.51re 0.00cp 0avio 3672k systemd-timedat
2 0.00re 0.00cp 0avio 10236k apport-checkrep
2 0.01re 0.00cp 0avio 4316160k ThreadPoolForeg*
2 0.00re 0.00cp 0avio 8550k package-data-do
3 0.79re 0.00cp 0avio 2156k dbus-daemon
12 0.00re 0.00cp 0avio 39631k ffmpeg
[...]3.2. View number of processes and CPU minutes
To print the number of processes and number of CPU minutes on a per-user basis, run sa command with -m flag:
$ sa -m
Sample output:
1525 1598.63re 0.23cp 0avio 32651k root 561 647.23re 0.09cp 0avio 3847k ostechnix 825 780.79re 0.08cp 0avio 47788k gdm 117 13.43re 0.06cp 0avio 63715k colord 2 52.01re 0.00cp 0avio 89720k geoclue 1 1.01re 0.00cp 0avio 70608k jellyfin 12 0.00re 0.00cp 0avio 39631k man 1 0.00re 0.00cp 0avio 3124k kernoops 4 104.12re 0.00cp 0avio 3270k sshd 1 0.05re 0.00cp 0avio 3856k whoopsie 1 0.00re 0.00cp 0avio 8552k
3.3. Print user id and command name
For each command in the accounting file, print the userid and command name using -u flag.
$ sa -u
Sample output:
root 0.00 cpu 693k mem 0 io accton root 0.00 cpu 3668k mem 0 io systemd-tty-ask root 0.00 cpu 3260k mem 0 io systemctl root 0.01 cpu 3764k mem 0 io deb-systemd-inv root 0.00 cpu 722k mem 0 io acct.postinst root 0.00 cpu 704k mem 0 io rm root 0.00 cpu 939k mem 0 io cp root 0.00 cpu 704k mem 0 io rm root 0.00 cpu 951k mem 0 io find root 0.00 cpu 911k mem 0 io gzip root 0.00 cpu 722k mem 0 io sh root 0.00 cpu 748k mem 0 io install-info root 0.00 cpu 911k mem 0 io gzip [...]
For more details, refer the man pages.
$ man sa
4. The dump-acct and dump-utmp command examples
The dump-acct utility displays the output file from the accton format to a human-readable format.
$ dump-acct /var/account/pacct
dump-utmp displays utmp files in human-readable format.
$ dump-utmp /var/run/utmp
For more details, refer the man pages.
$ man dump-acct
$ man dump-utmp
5. The accton command examples
The accton command will allow you to turn on or turn off accounting.
To turn on process accounting, run:
$ accton on
To turn it off, run:
$ accton off
For more details, refer the man pages.
$ man accton
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Conclusion
Every Linux administrator should be aware of GNU accounting utilities to keep an eye on all users. These utilities will be quite helpful in troubleshooting time.
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