How To Find Exact Installation Date And Time Of Your Linux OS

I am always curious to know small interesting things about Linux. Today, a question popped out in my mind. How long have I been using my Arch Linux OS? I have no idea when I installed my Arch Linux. It is working very well since it was installed. I am sure it was an year ago. But, I don't know the exact day. Have you ever wondered how long have you been using your Linux OS without a reinstall? Read on to find exact installation date and time of your Linux OS.

Find Exact Linux Installation Date And Time

There are a few ways to find Linux operating system's installation date and time. Here I have given all possible ways.

1. Using Stat Command

The stat command displays file or file system status in Linux and Unix-like systems. Stat command is part of GNU coreutils package, so you don't need to install it.

To check Linux OS installation date with stat command, simply run:

$ stat / | grep "Birth" | sed 's/Birth: //g' | cut -b 2-11
2021-05-20

You can also use awk with stat command to display Linux installation date as well:

$ stat / | awk '/Birth: /{print $2}'
2021-05-20

There is no need to use grep or sed or awk command. Stat command also has a built-in flag to check exact Linux installation date and time.

$ stat -c %w /
2021-05-20 17:31:10.000000000 +0530

As you can see in the above outputs, the installation date and time of my Fedora Linux desktop is May 20, 2021.

2. Analyze Pacman Logs On Arch Linux

If you use Arch Linux and its derivatives like EndeavourOS and Manjaro Linux, you can easily find how long have you been using it without a reinstall by analyzing the pacman logs as shown below.

$ head -n1 /var/log/pacman.log

Sample output from my Arch Linux system:

[2016-05-05 13:10] [PACMAN] Running 'pacman -r /mnt -Sy --print-format=%s --cachedir=/mnt/var/cache/pacman/pkg --noconfirm base sudo grub wireless_tools wpa_supplicant wpa_actiond netctl dialog os-prober'

As you see in the above, I am still using my first installation from May, 05 2016.

Even though Arch Linux is rolling release model, I have never had to reinstall Arch Linux. It works perfectly well without breaking anything. I have 3 Arch Linux systems (One host and two vms) over the years, and I've never had to "reinstall" even once. And, I am sure I am not going to reinstall it anytime soon.

3. Check Syslog Entries On Debian-based systems

On Debian, Ubuntu and other DEB-based systems, look in the "syslog" entries to get Linux OS installation date and time

$ sudo head -n1 /var/log/installer/syslog

Sample output:

Jul 2 10:29:10 ubuntu systemd[1]: Starting Flush Journal to Persistent Storage...

What If the logs are deleted already? No problem. You still can find out the installation time of your Linux OS by verifying filesystem creation date as shown in the following section.

4. Check Filesystem Creation Date

As stated, sometimes, you might have deleted the logs (or enabled log rotation). In such cases, you can find the installation date like below.

Switch to root user:

$ sudo su

Now, run any one of the following commands as root user.

# fs=$(df / | tail -1 | cut -f1 -d' ') && tune2fs -l $fs | grep 'Filesystem created'

Or,

# tune2fs -l /dev/sda1 | grep 'Filesystem created:'

Or,

# dumpe2fs /dev/sda1 | grep 'Filesystem created:'

Replace /dev/sda1 with correct hdd drive partition.

It will display when the file system was originally created.

Sample output:

Filesystem created:       Thu May 20 17:31:06 2021

These commands will work on all Linux distributions that supports ext4 filesystems.

5. Using Basesystem

Basesystem defines the components of a basic Fedora system (for example, the package installation order to use during bootstrapping). Basesystem should be in every installation of a system, and it should never be removed.

On Fedora, RHEL and its clones such as CentOS, AlmaLinux, and Rocky Linux, you can find Linux install date using command:

$ sudo rpm -qi basesystem

Sample output:

Name        : basesystem
Version     : 11
Release     : 11.fc34
Architecture: noarch
Install Date: Friday 23 April 2021 04:26:31 PM
Group       : Unspecified
Size        : 0
License     : Public Domain
Signature   : RSA/SHA256, Tuesday 26 January 2021 07:17:35 AM, Key ID 1161ae6945719a39
Source RPM  : basesystem-11-11.fc34.src.rpm
Build Date  : Tuesday 26 January 2021 07:15:29 AM
Build Host  : buildhw-x86-04.iad2.fedoraproject.org
Packager    : Fedora Project
Vendor      : Fedora Project
Bug URL     : https://bugz.fedoraproject.org/basesystem
Summary     : The skeleton package which defines a simple Fedora system
Description :
Basesystem defines the components of a basic Fedora system
(for example, the package installation order to use during bootstrapping).
Basesystem should be in every installation of a system, and it
should never be removed.

Or, to display the installation date only, run this:

$ sudo rpm -qi basesystem | grep Install
Install Date: Friday 23 April 2021 04:26:31 PM

Or use this command:

$ sudo rpm -q basesystem --qf '%{installtime:date}\n'
Friday 23 April 2021 04:26:31 PM

6. Using Install-date Script

There is a script named install-date, which is used to determine install date of an installation of Linux, using various methods. It currently works only on Arch Linux and Gentoo systems.

Go to the install-date repository on GitHub and download the script using command:

$ wget -O installdate.sh https://raw.githubusercontent.com/alicela1n/install-date/main/install-date

Watch out for the -O option. It must be UPPERCASE.

Make the script executable:

$ chmod +x installdate.sh

Now run the script to determine the date and time of Arch Linux installation:

$ ./installdate.sh 
2021-06-01

Conclusion

In this guide, I have listed 6 methods to find the exact installation date and time of a Linux distribution. Knowing your Linux installation date and time may not directly provide any benefits to you. However, you can use this information to find how long you're running a Linux distribution without reinstalling.

Featured Image Credit - Pixabay