If you're used to non-Red Hat Linuxes and migrating to RHEL, be
aware that as of RHEL 7, the OS can restrict access to /tmp
per-service with what Red hat calls 'private tmp', essentially a
privately mounted /tmp. This will break applications that rely on
standard /tmp for storage, most commonly Apache applications.
Disabling it is easy, here it how to do it in the case of the httpd
service:

root@quux:~# systemctl show httpd -p PrivateTmp
PrivateTmp=yes
root@quux:~# mkdir -p /etc/systemd/system/httpd.service.d/
root@quux:~# echo -e "[Service]\nPrivateTmp=false" > /etc/systemd/system/httpd.service.d/disable-privatetmp.conf
root@quux:~# systemctl daemon-reload
root@quux:~# systemctl restart httpd
root@quux:~# systemctl show httpd -p PrivateTmp
PrivateTmp=no
root@quux:~#

This was designed to fix a class of security issues where a process
writes to /tmp which is by design world-writable, and ideally
applications should be changed to not rely on /tmp. But this is not
always practical or even possible. So it definitely has a use, but
at least you can make an informed decision about using it.

And if you want to convert an application to using private tmp, just
add one line in the systemd service definition:

[Service]
PrivateTmp=true