Adding Some Useful SystemD Units

I use these kinds of things all the time when creating services,
timers, and mountpoints so I should keep them in the repo.

systemd/mount.automount

+[Unit]
+Description=Automount and Unmount a Filesystem
+After=network-online.target
+Wants=network-online.target
+
+[Automount]
+# Takes an absolute path of a directory of the
+# automount point. If the automount point does
+# not exist at time that the automount point is
+# installed, it is created. This string must be
+# reflected in the unit filename.
+Where=/mount
+
+# Directories of automount points (and any parent
+# directories) are automatically created if needed.
+# This option specifies the file system access mode
+# used when creating these directories. Takes an
+# access mode in octal notation.
+#DirectoryMode=0755
+
+# Configures an idle timeout. Once the mount has
+# been idle for the specified time, systemd will
+# attempt to unmount. Takes a unit-less value in
+# seconds, or a time span value such as "5min 20s".
+# Pass 0 to disable the timeout logic.
+#TimeoutIdleSec=0
+
+[Install]
+WantedBy=multi-user.target

systemd/mount.mount

+[Unit]
+Description=Mount a Filesystem Mount Point
+
+[Mount]
+# Takes an absolute path of a device node,
+# file or other resource to mount. See mount(8)
+# for details. If this refers to a device node,
+# a dependency on the respective device unit
+# is automatically created. (See
+# systemd.device(5) for more information.)
+# This option is mandatory. Note that the usual
+# specifier expansion is applied to this setting,
+# literal percent characters should hence be
+# written as "%%".
+What=/dev/sdx
+
+# Takes an absolute path of a directory for the
+# mount point; in particular, the destination
+# cannot be a symbolic link. If the mount point
+# does not exist at the time of mounting, it is
+# created. This string must be reflected in the
+# unit filename.
+Where=/mount
+
+# Takes a string for the file system type.
+# Type=btrfs
+
+# Mount options to use when mounting. This takes
+# a comma-separated list of options. This setting
+# is optional. Note that the usual specifier
+# expansion is applied to this setting, literal
+# percent characters should hence be written as "%%".
+#Options=
+
+# If true, parsing of the options specified in
+# Options= is relaxed, and unknown mount
+# options are tolerated.
+#SloppyOptions=false
+
+# If true, detach the filesystem from the
+# filesystem hierarchy at time of the unmount
+# operation, and clean up all references to the
+# filesystem as soon as they are not busy anymore.
+# This corresponds with umount(8)'s -l switch.
+#LazyUnmount=false
+
+# If true, force an unmount (in case of an
+# unreachable NFS system). This corresponds with
+# umount(8)'s -f switch.
+#ForceUnmount=false
+
+# Directories of mount points (and any parent
+# directories) are automatically created if needed.
+# This option specifies the file system access mode
+# used when creating these directories. Takes an
+# access mode in octal notation.
+#DirectoryMode=0755
+
+# Configures the time to wait for the mount command
+# to finish. If a command does not exit within the
+# configured time, the mount will be considered failed
+# and be shut down again. All commands still running
+# will be terminated forcibly via SIGTERM, and after
+# another delay of this time with SIGKILL. (See
+# KillMode= in systemd.kill(5).) Takes a unit-less
+# value in seconds, or a time span value such as 
+# "5min 20s". Pass 0 to disable the timeout logic.
+#TimeoutSec=20s
+
+[Install]
+WantedBy=multi-user.target

systemd/path.path

+[Unit]
+Description=Start Unit When Path Exists
+
+[Path]
+PathExists=/path/to/watch
+#PathExistsGlob=
+#PathChanged=
+#PathModified=
+#DirectoryNotEmpty=
+Unit=service_to_start.service
+
+[Install]
+WantedBy=paths.target

systemd/simple.service

+[Unit]
+Description=Service Description
+ConditionPathExists=/path/that/must/exist/to/run/service
+
+[Service]
+Type=Simple
+ExecStartPre=/absolute/path/to/executable --before --ExecStart
+ExecStart=/absolute/path/to/executable --arg1
+ExecStartPost=/absolute/path/to/executable --after --ExecStart
+ExecReload=/absolute/path/to/config_test
+ExecReload=/absolute/path/to/executable --reload
+Restart=always
+RestartSec=30s
+
+[Install]
+WantedBy=multi-user.target

systemd/timer.timer

+[Unit]
+Description=Run A Service on a Timer
+
+[Timer]
+#OnActiveSec=
+OnBootSec=5m
+#OnStartupSec=
+OnUnitActiveSec=1h
+#OnUnitInactiveSec=
+
+# OnCalendar Valid Time Specs
+# https://www.freedesktop.org/software/systemd/man/systemd.time.html#
+#OnCalendar=
+
+# Delay the timer by a randomly selected, evenly distributed
+# amount of time between 0 and the specified time value.
+#RandomizedDelaySec=
+
+Unit=service_to_start.service
+
+# If true, the time when the service unit was last triggered
+# is stored on disk. When the timer is activated, the service
+# unit is triggered immediately if it would have been
+# triggered at least once during the time when the timer was
+# inactive. This is useful to catch up on missed runs of the
+# service when the machine was off. Note that this setting only
+# has an effect on timers configured with OnCalendar=.
+#Persistent=false
+
+# If true, an elapsing timer will cause the system to resume
+# from suspend, should it be suspended and if the system
+# supports this. Note that this option will only make sure the
+# system resumes on the appropriate times, it will not take
+# care of suspending it again after any work that is to be
+# done is finished.
+#WakeSystem=false
+
+[Install]
+WantedBy=timers.target