Find the Exact Installation Date And Time Of Your Linux OS

On Fedora, RHEL, and its clones such as CentOS, Scientific Linux, and Oracle Linux, you can find it using the following command:

rpm -qi basesystem

Sample output

[root@server ~]# rpm -qi basesystem
Name : basesystem
Version : 10.0
Release : 7.el7.centos
Architecture: noarch
Install Date: Thu 29 Mar 2018 05:05:32 PM IST
Group : System Environment/Base
Size : 0
License : Public Domain
Signature : RSA/SHA256, Fri 04 Jul 2014 06:16:57 AM IST, Key ID 24c6a8a7f4a80eb5
Source RPM : basesystem-10.0-7.el7.centos.src.rpm
Build Date : Fri 27 Jun 2014 04:07:10 PM IST
Build Host : worker1.bsys.centos.org
Relocations : (not relocatable)
Packager : CentOS BuildSystem http://bugs.centos.org
Vendor : CentOS
Summary : The skeleton package which defines a simple CentOS Linux system
Description :
Basesystem defines the components of a basic CentOS Linux
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.