CentOS7下，系统使用systemd管理易变与临时文件，与之相关的系统服务有3个：

systemd-tmpfiles-setup.service  ：Create Volatile Files and Directories
systemd-tmpfiles-setup-dev.service：Create static device nodes in /dev
systemd-tmpfiles-clean.service ：Cleanup of Temporary Directories

配置文件也有3个地方：

/etc/tmpfiles.d/.conf
/run/tmpfiles.d/.conf
/usr/lib/tmpfiles.d/*.conf

/tmp目录的清理规则主要取决于/usr/lib/tmpfiles.d/tmp.conf文件的设定，默认的配置内容为：

# This file is part of systemd.
# systemd is free software; you can redistribute it and/or modify itunder the terms of the GNU Lesser General Public License as published bythe Free Software Foundation; either version 2.1 of the License, or(at your option) any later version.See tmpfiles.d(5) for detailsClear tmp directories separately, to make them easier to overridev /tmp 1777 root root 7d
v /var/tmp 1777 root root 30dExclude namespace mountpoints created with PrivateTmp=yesx /tmp/systemd-private-%b-*
X /tmp/systemd-private-%b-/tmp
x /var/tmp/systemd-private-%b-
X /var/tmp/systemd-private-%b-*/tmp

如你不想让系统自动清理/tmp下以sock结尾文件，那么增加下面这条内容到配置文件中即可：

x /tmp/*.sock