Compatible with Amazon Linux AMI release

include/check_os.sh

@@ -13,7 +13,7 @@ if [ -n "`grep 'Aliyun Linux release' /etc/issue`" -o -e /etc/redhat-release ];t
     [ -n "`grep ' 7\.' /etc/redhat-release`" ] && CentOS_RHEL_version=7
     [ -n "`grep ' 6\.' /etc/redhat-release`" -o -n "`grep 'Aliyun Linux release6 15' /etc/issue`" ] && CentOS_RHEL_version=6
     [ -n "`grep ' 5\.' /etc/redhat-release`" -o -n "`grep 'Aliyun Linux release5' /etc/issue`" ] && CentOS_RHEL_version=5
-elif [-n "`grep 'Amazon Linux AMI release' /etc/issue`" -o -e /etc/system-release ];then
+elif [ -n "`grep 'Amazon Linux AMI release' /etc/issue`" -o -e /etc/system-release ];then
     OS=CentOS
     CentOS_RHEL_version=6
 elif [ -n "`grep bian /etc/issue`" -o "`lsb_release -is 2>/dev/null`" == 'Debian' ];then