Linux下关于/tmp目录的清理规则

转自：

RHEL7
systemd-tmpfiles-clean.service服务

Linux下该服务的执行可以根据systemd-tmpfiles-clean.timer进行管理

[root@VM-0-17-centos /]# cat /usr/lib/systemd/system/systemd-tmpfiles-clean.timer
#  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.

[Unit]
Description=Daily Cleanup of Temporary Directories
Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)

[Timer]
OnBootSec=15min
OnUnitActiveSec=1d

上述配置文件表示两种情况会执行该服务

• 开机15分钟执行服务
• 距离上次执行该服务1天后执行服务

[root@VM-0-17-centos /]# cat /usr/lib/systemd/system/systemd-tmpfiles-clean.service
#  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.

[Unit]
Description=Cleanup of Temporary Directories
Documentation=man:tmpfiles.d(5) man:systemd-tmpfiles(8)
DefaultDependencies=no
Conflicts=shutdown.target
After=systemd-readahead-collect.service systemd-readahead-replay.service local-fs.target time-sync.target
Before=shutdown.target

[Service]
Type=oneshot
ExecStart=/usr/bin/systemd-tmpfiles --clean
IOSchedulingClass=idle

命令： /usr/bin/systemd-tmpfiles

[root@VM-0-17-centos /]# /usr/bin/systemd-tmpfiles --help
systemd-tmpfiles [OPTIONS...] [CONFIGURATION FILE...]

Creates, deletes and cleans up volatile and temporary files and directories.

  -h --help                 Show this help
     --version              Show package version
     --create               Create marked files/directories
     --clean                Clean up marked directories
     --remove               Remove marked files/directories
     --boot                 Execute actions only safe at boot
     --prefix=PATH          Only apply rules with the specified prefix
     --exclude-prefix=PATH  Ignore rules with the specified prefix
     --root=PATH            Operate on an alternate filesystem root

哪些目录被标记，又是什么样的标记呢？

定义在配置文件/usr/lib/tmpfiles.d/tmp.conf中

配置文件： /usr/lib/tmpfiles.d/tmp.conf

[root@VM-0-17-centos /]# cat /usr/lib/tmpfiles.d/tmp.conf
#  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
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

上述配置表示：

• 清理/tmp目录超过10天的内容，但是匹配/tmp/systemd-private-%b-*的目录及其路径下的全部内容会被保留

• 清理/var/tmp目录超过30天的内容，但是匹配/var/tmp/systemd-private-%b-*的目录及其路径下的全部内容被保留

总结

• RHEL6 根据文件的访问时间等条件使用tmpwatch命令进行/tmp目录的清理，可以使用crond daemon进行定期执行

• RHEL7 根据服务systemd-tmpfiles-clean.service 进行临时文件的清理，清理规则定义在配置文件/usr/lib/tmpfiles.d/tmp.conf，调用命令为/usr/bin/systemd-tmpfiles --clean，执行时间依靠systemd-tmpfiles-clean.timer进行管理