This knowledge base article shows several different commands that may be used to determine the version of Linux that is running on the system being accessed, and what brand of Linux (i. e., Red Hat or SUSE.)

The basic operating system information command is uname, but this command does not tell which release of Linux is being used.
 
For example, note the output of these two commands.  In both cases the version information can be determined from the output, but it is not obvious.

• On SUSE, running uname shows the following.  The data returned from the uname command does not specifically indicate which operating system type is running.

$ uname -a

Linux acm-710 4.4.103-92.56-default #1 SMP Wed Dec 27 16:24:31 UTC 2017 (2fd2155) x86_64 x86_64 x86_64 GNU/Linux

• With Red Hat we see the information below.  The el6 inicates Red Hat.

$ uname -a

Linux acm-701rh 2.6.32-431.el6.x86_64 #1 SMP Sun Nov 10 22:19:54 EST 2013 x86_64 x86_64 x86_64 GNU/Linux

The string of 2.6.32-431.el6.x86_64 represents Red Hat 6.5, but the specific string of Red Hat 6.5 is not part of the output.

There are several commands and methods that can be used to determine the Linux distribution installed. These include:

1.  Login via a terminal

After a successful login,  the banner that displays will show the Operating System information. For example,

• SUSE

login as: oracle
Using keyboard-interactive authentication.
Password: <enter oracle user password>
Last login: Tue Nov 30 11:12:32 2010 from 192.168.8.17
Kickstart-installed SuSE Linux Thu Oct 21 10:07:48 EDT 2018

• Red Hat

login as: oracle
oracle@vm-support-42's password:<enter oracle user password>
Last login: Wed Nov 17 11:50:07 2010 from 192.168.8.19
Kickstart-installed Red Hat Linux Wed Oct 27 10:54:47 EDT 2018 

2. Print  out the version using the command cat /proc/version  or uname -a

Platform version information is kept in the /proc/version file.  Review of this file provides operating system information.

• SUSE

 Linux version 2.6.27.19-5-default (geeko@buildhost) (gcc version 4.3.2 [gcc-4_3-branch revision 141291]
(SUSE Linux) ) #1 SMP 2009-02-28 04:40:21 +0100 

• Red Hat

Linux version 2.6.32-431.el6.x86_64 ( mockbuild@x86-023.build.eng.bos.redhat.com) (gcc version 4.4.7
20120313 (Red Hat 4.4.7-4) (GCC) ) #1 SMP Sun Nov 10 22:19:54 EST 2013

Linux acm-701rh 2.6.32-431.el6.x86_64 #1 SMP Sun Nov 10 22:19:54 EST 2013 x86_64 x86_64 x86_64 GNU/Linux

  For reference, these values correspond to these versions of Red Hat: 
 

3.  Linux command that can be used to determine the OS:   lsb_release -a

Another Linux command that shows the operating system type is lsb_release -a.
 

• SUSE

LSB Version: n/a
Distributor ID: SUSE
Description: SUSE Linux Enterprise Server 12 SP2
Release: 12.2 Codename: n/a

• Red Hat

LSB Version:    :core-4.0-amd64:core-4.0-ia32:core-4.0 noarch:graphics-4.0-amd64:graphics-4.0-ia32:graphics-4.0-noarch:printing-4.0 amd64:printing-4.0-ia32:printing-4.0-noarch Distributor ID: RedHatEnterpriseServer
Description:    Red Hat Enterprise Linux Server release 5.8 (Tikanga)
Release:        5.8 Codename:       Tikanga

4. Check for the existence of certain operating system-specific files in the /etc directory

Another simple way to determine the operating system type is to check for the existence of certain OS-specific files in the /etc directory:

• On a SUSE system, these files begin with 'suse'.
• On a Red Hat system, these files begin with 'red'.

Files beginning with suse will not exist on a Red Hat system and files beginning with red will not exist on a SUSE system.

• SUSE

$ ls /etc/red*

ls: cannot access /etc/red*: No such file or directory

$ cd /etc
$ ls -la | grep -i suse

-rw-r--r--   1 root   root         17 Oct 25  2016 SUSE-brand
-rw-r--r--   1 root   root        377 Jun 14  2017 SUSEConnect.example
drwxr-xr-x   3 root   root       4096 Feb 15  2018 susehelp.d
-rw-r--r--   1 root   root        215 Oct 25  2016 SuSE-release

• Red Hat

$ ls /etc/suse*

ls: /etc/suse*: No such file or directory

$ ls -la | grep -i red

drwxr-xr-x.   2 root   root       4096 Mar  1  2017 redhat-lsb
-rw-r--r--.   1 root   root         55 Oct 30  2013 redhat-release l
rwxrwxrwx.   1 root   root         14 Mar  1  2017 system-release -> redhat-release