Unit
[Unit]
This is common to all unit types. It contains metadata about the service such as a description.
systemd.unit(5)
/usr/lib/systemd/system/nginx.service
[Unit]
Description=nginx web server
After=network-online.target remote-fs.target nss-lookup.target
Wants=network-online.target
/usr/lib/systemd/system/postgresql.service
[Unit]
Description=PostgreSQL database server
Documentation=man:postgres(1)
After=network.target network-online.target
Wants=network-online.target
/usr/lib/systemd/system/tmp.mount
[Unit]
Description=Temporary Directory /tmp
Documentation=https://systemd.io/TEMPORARY_DIRECTORIES
Documentation=man:file-hierarchy(7)
Documentation=https://systemd.io/API_FILE_SYSTEMS
ConditionPathIsSymbolicLink=!/tmp
DefaultDependencies=no
Conflicts=umount.target
Before=local-fs.target umount.target
After=swap.target