Resolve write error message about cache_tmp folder on website
for CentOS
1. enable selinux to permit httpd_unified
$ setsebool -P httpd_unified 1
2. go to parent folder of cache_tmp if it could not be written
$ semanage fcontext -a -t httpd_sys_rw_content_t 'cache_tmp'
$ restorecon -v 'cache_tmp'
Reference
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/selinux_users_and_administrators_guide/sect-managing_confined_services-the_apache_http_server-booleans
SElinux Alert Browser GUI