不要在/tmp目录下保存文件，该目录会定期清理文件
/tmp默认保存10天
/var/tmp默认保存30天
配置文件：/usr/lib/tmpfiles.d/tmp.conf
默认配置文件：
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
# See tmpfiles.d(5) for details
# Clear tmp directories separately, to make them easier to override
# 默认保留时间变为了10天，如果这10天内没做任何调整，会被处理
v /tmp 1777 root root 10d
v /var/tmp 1777 root root 30d
# Exclude namespace mountpoints created with PrivateTmp=yes
x /tmp/systemd-private-%b-*
X /tmp/systemd-private-%b-*/tmp
x /var/tmp/systemd-private-%b-*
X /var/tmp/systemd-private-%b-*/tmp