Just getting started with openstack and trying to install devstack on CentOS 6.8 but I keep getting errors.

[prabal@prabal devstack]$ ./stack.sh + unset GREP_OPTIONS + unset LANG + unset LANGUAGE + LC_ALL=C + export LC_ALL + umask 022 + PATH=/usr/lib64/qt-3.3/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/prabal/bin:/usr/local/sbin:/usr/sbin:/sbin +++ dirname ./stack.sh ++ cd . ++ pwd + TOP_DIR=/devstack + NOUNSET= + [[ -n '' ]] ++ date +%s + DEVSTACK_START_TIME=1481867827 + [[ -r /devstack/.stackenv ]] + FILES=/devstack/files + '[' '!' -d /devstack/files ']' + '[' '!' -d /devstack/inc ']' + '[' '!' -d /devstack/lib ']' + [[ '' == \y ]] + [[ 500 -eq 0 ]] + [[ -n '' ]] + [[ -e /home/prabal/.no-devstack ]] + LAST_SPINNER_PID= + source /devstack/functions ++ [[ -z '' ]] ++ declare -r _DEVSTACK_FUNCTIONS=1 ++++ dirname /devstack/functions +++ cd /devstack +++ pwd ++ FUNC_DIR=/devstack ++ source /devstack/functions-common ++++ set +o ++++ grep xtrace +++ _XTRACE_FUNCTIONS_COMMON='set -o xtrace' +++ set +o xtrace /devstack/functions-common: line 162: conditional binary operator expected /devstack/functions-common: line 162: syntax error near "$1"' /devstack/functions-common: line 162: [[ -v "$1" ]]' ./stack.sh: line 150: GetDistro: command not found /devstack/stackrc: line 52: isset: command not found /devstack/stackrc: line 560: is_package_installed: command not found /devstack/stackrc: line 760: get_default_host_ip: command not found /devstack/stackrc: line 762: die: command not found /devstack/stackrc: line 765: get_default_host_ip: command not found WARNING: this script has not been tested on ./stack.sh: line 198: die: command not found ./stack.sh: line 216: export_proxy_variables: command not found ./stack.sh: line 221: disable_negated_services: command not found ./stack.sh: line 228: is_package_installed: command not found ./stack.sh: line 228: install_package: command not found ./stack.sh: line 259: is_ubuntu: command not found ./stack.sh: line 319: safe_chown: command not found ./stack.sh: line 320: safe_chmod: command not found mkdir: cannot create directory `/opt/stack/logs': Permission denied ./stack.sh: line 330: safe_chown: command not found ./stack.sh: line 352: is_fedora: command not found ./stack.sh: line 359: is_package_installed: command not found ./stack.sh: line 359: install_package: command not found Linux prabal.guavus 2.6.32-642.11.1.el6.x86_64 #1 SMP Fri Nov 18 19:25:05 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux /devstack/lib/databases/mysql: line 20: is_fedora: command not found /devstack/lib/database: line 46: is_service_enabled: command not found /devstack/lib/database: line 46: is_service_enabled: command not found ./stack.sh: line 544: is_service_enabled: command not found ./stack.sh: line 552: fetch_plugins: command not found stack.sh failed Error on exit ./stack.sh: line 501: /opt/stack/devstack.subunit: Permission denied [prabal@prabal devstack]$