If you're sysadmin who inherited a few hundreds of Linux machines from a previous admin and you're in process of investigating how things were configured by the previous administrator one of the crucial things to find out might be
How Long ago was Linux installed?
Here is how to check the Linux OS install date.
The universal way nomatter the Linux distribution is to use fullowing command:
root@pcfreak:~# tune2fs -l /dev/sda1 | grep 'Filesystem created:'
Filesystem created: Thu Sep 6 21:44:22 2012
Above command assumes the Linux's root partition / is installed on /dev/sda1 however if your case is different, e.g. the primary root partition is installed on /dev/sda2 or /dev/sdb1 / dev/sdb2 etc. just place the right first partition into the command.
If primary install root partition is /dev/sdb1 for example:
root@pcfreak:~# tune2fs -l /dev/sdb1 | grep 'Filesystem created:'
To find out what is the root partition of the Linux server installed use fdisk command:
root@pcfreak:~# fdisk -l
Disk /dev/sda: 465,8 GiB, 500107862016 bytes, 976773168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00051edaDevice Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 965193727 965191680 460,2G 83 Linux
/dev/sda2 965195774 976771071 11575298 5,5G 5 Extended
/dev/sda5 965195776 976771071 11575296 5,5G 82 Linux swap / SolarisDisk /dev/sdb: 111,8 GiB, 120034123776 bytes, 234441648 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000
Other ways to check the Linux OS install date on Debian / Ubuntu / Mint etc. deb. based GNU / Linux
Deban based Linux distributions do create an initial /var/log/installer directory containing various install information such as hardware-summary, partition, initial installed deb packages, exact version of Linux distribution, and the way it was installed either it was installed from an ISO image, or it was network install etc.
root@pcfreak:~# ls -al /var/log/installer/
total 1228
drwxr-xr-x 3 root root 4096 sep 6 2012 ./
drwxr-xr-x 72 root root 12288 окт 22 06:26 ../
drwxr-xr-x 2 root root 4096 sep 6 2012 cdebconf/
-rw-r–r– 1 root root 17691 sep 6 2012 hardware-summary
-rw-r–r– 1 root root 163 sep 6 2012 lsb-release
-rw——- 1 root root 779983 sep 6 2012 partman
-rw-r–r– 1 root root 51640 sep 6 2012 status
-rw——- 1 root root 363674 sep 6 2012 syslog
If those directory is missing was wiped out by the previous administrator, to clear up traces of his previous work before he left job another possible way to find out exact install date is to check timestamp of /lost+found directory;
root@pcfreak:~# ls -ld /lost+found/
drwx—— 2 root root 16384 sep 6 2012 /lost+found//
Check OS Linux install date on (Fedora, CentOS, Scientific Linux, Oracle and other Redhat RPM based Distros)
[root@centos: ~]# rpm -qi basesystem
Name : basesystem
Version : 10.0
Release : 7.el7
Architecture: noarch
Install Date: Mon 02 May 2016 19:20:58 BST
Group : System Environment/Base
Size : 0
License : Public Domain
Signature : RSA/SHA256, Tue 01 Apr 2014 14:23:16 BST, Key ID 199e2f91fd431d51
Source RPM : basesystem-10.0-7.el7.src.rpm
Build Date : Fri 27 Dec 2013 17:22:15 GMT
Build Host : ppc-015.build.eng.bos.redhat.com
Relocations : (not relocatable)
Packager : Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
Vendor : Red Hat, Inc.
Summary : The skeleton package which defines a simple Red Hat Enterprise Linux system
Description :
Basesystem defines the components of a basic Red Hat Enterprise 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.
