cd /etc
ll *release
-rw-r--r-- 1 root root 38 Oct 8 2018 centos-release
-rw-r--r-- 1 root root 393 Oct 8 2018 os-release
lrwxrwxrwx 1 root root 14 Nov 28 2018 redhat-release -> centos-release
lrwxrwxrwx 1 root root 14 Nov 28 2018 system-release -> centos-release
cat cat os-release
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"
CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"
cat centos-release
CentOS Linux release 7.5.1804 (Core)