There are chances that you have to develop scripts which need to do different things for the individual Linux distributions and their major and minor version. The file /etc/os-release is the place to go.

Execute the command:

source /etc/os-release

in your bash script and you will have the variables set which matter.

Here is a collection of the various /etc/os-release flavors I'm working with

Amazon Linux

NAME="Amazon Linux AMI"
VERSION="2016.03"
ID="amzn"
ID_LIKE="rhel fedora"
VERSION_ID="2016.03"
PRETTY_NAME="Amazon Linux AMI 2016.03"
ANSI_COLOR="0;33"
CPE_NAME="cpe:/o:amazon:linux:2016.03:ga"
HOME_URL="http://aws.amazon.com/amazon-linux-ami/"

Oracle Linux

Oracle Linux 6.8

NAME="Oracle Linux Server" 
VERSION="6.8" 
ID="ol" 
VERSION_ID="6.8" 
PRETTY_NAME="Oracle Linux Server 6.8" 
ANSI_COLOR="0;31" 
CPE_NAME="cpe:/o:oracle:linux:6:8:server"
HOME_URL="https://linux.oracle.com/" 
BUG_REPORT_URL="https://bugzilla.oracle.com/" 
ORACLE_BUGZILLA_PRODUCT="Oracle Linux 6" 
ORACLE_BUGZILLA_PRODUCT_VERSION=6.8 
ORACLE_SUPPORT_PRODUCT="Oracle Linux" 
ORACLE_SUPPORT_PRODUCT_VERSION=6.8

Oracle Linux 7.1

NAME="Oracle Linux Server"
VERSION="7.1"
ID="ol"
VERSION_ID="7.1"
PRETTY_NAME="Oracle Linux Server 7.1"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:oracle:linux:7:1"
HOME_URL="https://linux.oracle.com/"
BUG_REPORT_URL="https://bugzilla.oracle.com/"
ORACLE_BUGZILLA_PRODUCT="Oracle Linux 7"
ORACLE_BUGZILLA_PRODUCT_VERSION=7.1
ORACLE_SUPPORT_PRODUCT="Oracle Linux"
ORACLE_SUPPORT_PRODUCT_VERSION=7.1

Oracle Linux 7.3

NAME="Oracle Linux Server"
VERSION="7.3"
ID="ol"
VERSION_ID="7.3"
PRETTY_NAME="Oracle Linux Server 7.3"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:oracle:linux:7:3:server"
HOME_URL="https://linux.oracle.com/"
BUG_REPORT_URL="https://bugzilla.oracle.com/"
ORACLE_BUGZILLA_PRODUCT="Oracle Linux 7"
ORACLE_BUGZILLA_PRODUCT_VERSION=7.3
ORACLE_SUPPORT_PRODUCT="Oracle Linux"
ORACLE_SUPPORT_PRODUCT_VERSION=7.3

Oracle Linux 7.4

NAME="Oracle Linux Server"
VERSION="7.4"
ID="ol"
VERSION_ID="7.4"
PRETTY_NAME="Oracle Linux Server 7.4"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:oracle:linux:7:4:server"
HOME_URL="https://linux.oracle.com/"
BUG_REPORT_URL="https://bugzilla.oracle.com/"
ORACLE_BUGZILLA_PRODUCT="Oracle Linux 7"
ORACLE_BUGZILLA_PRODUCT_VERSION=7.4
ORACLE_SUPPORT_PRODUCT="Oracle Linux"
ORACLE_SUPPORT_PRODUCT_VERSION=7.4
 

Red Hat

Red Hat Enterprise Linux Server 7.2

NAME="Red Hat Enterprise Linux Server"
VERSION="7.2 (Maipo)"
ID="rhel"
ID_LIKE="fedora"
VERSION_ID="7.2"
PRETTY_NAME="Red Hat Enterprise Linux Server 7.2 (Maipo)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:redhat:enterprise_linux:7.2:GA:server"
HOME_URL="https://www.redhat.com/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Red Hat Enterprise Linux 7"
REDHAT_BUGZILLA_PRODUCT_VERSION=7.2
REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="7.2"

Red Hat Enterprise Linux Server 7.3

NAME="Red Hat Enterprise Linux Server"
VERSION="7.3 (Maipo)"
ID="rhel"
ID_LIKE="fedora"
VERSION_ID="7.3"
PRETTY_NAME="Red Hat Enterprise Linux Server 7.3 (Maipo)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:redhat:enterprise_linux:7.3:GA:server"
HOME_URL="https://www.redhat.com/"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Red Hat Enterprise Linux 7"
REDHAT_BUGZILLA_PRODUCT_VERSION=7.3
REDHAT_SUPPORT_PRODUCT="Red Hat Enterprise Linux"
REDHAT_SUPPORT_PRODUCT_VERSION="7.3"

 

SUSE SLES

SUSE Linux Enterprise Server 11 SP3

This distribution doesn't have an /etc/os-release file. This version has a file /etc/SuSE-release.

SUSE Linux Enterprise Server 11 (x86_64)
VERSION = 11
PATCHLEVEL = 3

SLES for SAP 12 SP1

NAME="SLES_SAP"
VERSION="12-SP1"
VERSION_ID="12.1.0.1"
PRETTY_NAME="SUSE Linux Enterprise Server for SAP Applications 12 SP1"
ID="sles_sap"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:suse:sles_sap:12:sp1"

SLES 12 SP2

NAME="SLES"
VERSION="12-SP2"
VERSION_ID="12.2"
PRETTY_NAME="SUSE Linux Enterprise Server 12 SP2"
ID="sles"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:suse:sles:12:sp2" 

SLES 12 SP3

NAME="SLES"
VERSION="12-SP3"
VERSION_ID="12.3"
PRETTY_NAME="SUSE Linux Enterprise Server 12 SP3"
ID="sles"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:suse:sles:12:sp3"

SLES 15

NAME="SLES"
VERSION="15"
VERSION_ID="15"
PRETTY_NAME="SUSE Linux Enterprise Server 15"
ID="sles"
ID_LIKE="suse"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:suse:sles:15"