Revise and format systemd.md [ci skip]

docs/systemd.md

@@ -1,19 +1,18 @@
 # systemd
 
-[systemd](https://www.freedesktop.org/wiki/Software/systemd/) is a
-commonly available init system (PID 1) on many Linux distributions. It
-offers process monitoring (including automatic restarts) and other
-useful features for running Puma in production.
+[systemd](https://www.freedesktop.org/wiki/Software/systemd/) is a commonly
+available init system (PID 1) on many Linux distributions. It offers process
+monitoring (including automatic restarts) and other useful features for running
+Puma in production.
 
 ## Service Configuration
 
-Below is a sample puma.service configuration file for systemd, which
-can be copied or symlinked to `/etc/systemd/system/puma.service`, or if
-desired, using an application or instance specific name.
+Below is a sample puma.service configuration file for systemd, which can be
+copied or symlinked to `/etc/systemd/system/puma.service`, or if desired, using
+an application or instance-specific name.
 
-Note that this uses the systemd preferred "simple" type where the
-start command remains running in the foreground (does not fork and
-exit).
+Note that this uses the systemd preferred "simple" type where the start command
+remains running in the foreground (does not fork and exit).
 
 ~~~~ ini
 [Unit]
@@ -37,8 +36,8 @@ WatchdogSec=10
 # Preferably configure a non-privileged user
 # User=
 
-# The path to the your application code root directory.
-# Also replace the "<YOUR_APP_PATH>" place holders below with this path.
+# The path to your application code root directory.
+# Also replace the "<YOUR_APP_PATH>" placeholders below with this path.
 # Example /home/username/myapp
 WorkingDirectory=<YOUR_APP_PATH>
 
@@ -64,33 +63,31 @@ Restart=always
 WantedBy=multi-user.target
 ~~~~
 
-See [systemd.exec](https://www.freedesktop.org/software/systemd/man/systemd.exec.html)
+See
+[systemd.exec](https://www.freedesktop.org/software/systemd/man/systemd.exec.html)
 for additional details.
 
 ## Socket Activation
 
-systemd and puma also support socket activation, where systemd opens
-the listening socket(s) in advance and provides them to the puma
-master process on startup. Among other advantages, this keeps
-listening sockets open across puma restarts and achieves graceful
-restarts, including when upgraded puma, and is compatible with both
-clustered mode and application preload.
-
-**Note:** Any wrapper scripts which `exec`, or other indirections in
-`ExecStart`, may result in activated socket file descriptors being closed
-before they reach the puma master process. For example, if using `bundle exec`,
-pass the `--keep-file-descriptors` flag. `bundle exec` can be avoided by using a
-`puma` executable generated by `bundle binstubs puma`. This is tracked in
-[#1499].
-
-**Note:** Socket activation doesn't currently work on JRuby. This is
-tracked in [#1367].
-
-To use socket activation, configure one or more `ListenStream` sockets
-in a companion `*.socket` unit file. Also uncomment the associated
-`Requires` directive for the socket unit in the service file (see
-above.) Here is a sample puma.socket, matching the ports used in the
-above puma.service:
+systemd and Puma also support socket activation, where systemd opens the
+listening socket(s) in advance and provides them to the Puma master process on
+startup. Among other advantages, this keeps listening sockets open across puma
+restarts and achieves graceful restarts, including when upgraded Puma, and is
+compatible with both clustered mode and application preload.
+
+**Note:** Any wrapper scripts which `exec`, or other indirections in `ExecStart`
+may result in activated socket file descriptors being closed before reaching the
+puma master process. For example, if using `bundle exec`, pass the
+`--keep-file-descriptors` flag. `bundle exec` can be avoided by using a `puma`
+executable generated by `bundle binstubs puma`. This is tracked in [#1499].
+
+**Note:** Socket activation doesn't currently work on JRuby. This is tracked in
+[#1367].
+
+Configure one or more `ListenStream` sockets in a companion `*.socket` unit file
+to use socket activation. Also, uncomment the associated `Requires` directive
+for the socket unit in the service file (see above.) Here is a sample
+puma.socket, matching the ports used in the above puma.service:
 
 ~~~~ ini
 [Unit]
@@ -113,31 +110,32 @@ Backlog=1024
 WantedBy=sockets.target
 ~~~~
 
-See [systemd.socket](https://www.freedesktop.org/software/systemd/man/systemd.socket.html)
+See
+[systemd.socket](https://www.freedesktop.org/software/systemd/man/systemd.socket.html)
 for additional configuration details.
 
-Note that the above configurations will work with Puma in either
-single process or cluster mode.
+Note that the above configurations will work with Puma in either single process
+or cluster mode.
 
 ### Sockets and symlinks
 
-When using releases folders, you should set the socket path using the
-shared folder path (ex. `/srv/projet/shared/tmp/puma.sock`), not the
-release folder path (`/srv/projet/releases/1234/tmp/puma.sock`).
+When using releases folders, you should set the socket path using the shared
+folder path (ex. `/srv/projet/shared/tmp/puma.sock`), not the release folder
+path (`/srv/projet/releases/1234/tmp/puma.sock`).
 
 Puma will detect the release path socket as different than the one provided by
-systemd and attempt to bind it again, resulting in the exception
- `There is already a server bound to:`.
+systemd and attempt to bind it again, resulting in the exception `There is
+already a server bound to:`.
 
 ### Binding
 
-By default you need to configure puma to have binds matching with all
+By default, you need to configure Puma to have binds matching with all
 ListenStream statements. Any mismatched systemd ListenStreams will be closed by
-puma.
+Puma.
 
 To automatically bind to all activated sockets, the option
 `--bind-to-activated-sockets` can be used. This matches the config DSL
-`bind_to_activated_sockets` statement. This will cause puma to create a bind
+`bind_to_activated_sockets` statement. This will cause Puma to create a bind
 automatically for any activated socket. When systemd socket activation is not
 enabled, this option does nothing.
 
@@ -146,8 +144,8 @@ binds that's not socket activated.
 
 ## Usage
 
-Without socket activation, use `systemctl` as root (e.g. via `sudo`) as
-with other system services:
+Without socket activation, use `systemctl` as root (i.e., via `sudo`) as with
+other system services:
 
 ~~~~ sh
 # After installing or making changes to puma.service
@@ -156,35 +154,35 @@ systemctl daemon-reload
 # Enable so it starts on boot
 systemctl enable puma.service
 
-# Initial start up.
+# Initial startup.
 systemctl start puma.service
 
 # Check status
 systemctl status puma.service
 
-# A normal restart. Warning: listeners sockets will be closed
+# A normal restart. Warning: listener's sockets will be closed
 # while a new puma process initializes.
 systemctl restart puma.service
 ~~~~
 
-With socket activation, several but not all of these commands should
-be run for both socket and service:
+With socket activation, several but not all of these commands should be run for
+both socket and service:
 
 ~~~~ sh
 # After installing or making changes to either puma.socket or
 # puma.service.
 systemctl daemon-reload
 
-# Enable both socket and service so they start on boot.  Alternatively
-# you could leave puma.service disabled and systemd will start it on
-# first use (with startup lag on first request)
+# Enable both socket and service, so they start on boot.  Alternatively
+# you could leave puma.service disabled, and systemd will start it on
+# the first use (with startup lag on the first request)
 systemctl enable puma.socket puma.service
 
-# Initial start up. The Requires directive (see above) ensures the
+# Initial startup. The Requires directive (see above) ensures the
 # socket is started before the service.
 systemctl start puma.socket puma.service
 
-# Check status of both socket and service.
+# Check the status of both socket and service.
 systemctl status puma.socket puma.service
 
 # A "hot" restart, with systemd keeping puma.socket listening and
@@ -197,8 +195,8 @@ systemctl restart puma.service
 systemctl restart puma.socket puma.service
 ~~~~
 
-Here is sample output from `systemctl status` with both service and
-socket running:
+Here is sample output from `systemctl status` with both service and socket
+running:
 
 ~~~~
 ● puma.socket - Puma HTTP Server Accept Sockets
@@ -231,14 +229,12 @@ Apr 07 08:40:19 hx puma[28320]: Use Ctrl-C to stop
 
 ### capistrano3-puma
 
-By default,
-[capistrano3-puma](https://github.com/seuros/capistrano-puma) uses
-`pumactl` for deployment restarts, outside of systemd.  To learn the
-exact commands that this tool would use for `ExecStart` and
-`ExecStop`, use the following `cap` commands in dry-run mode, and
-update from the above forking service configuration accordingly. Note
-also that the configured `User` should likely be the same as the
-capistrano3-puma `:puma_user` option.
+By default, [capistrano3-puma](https://github.com/seuros/capistrano-puma) uses
+`pumactl` for deployment restarts outside of systemd. To learn the exact
+commands that this tool would use for `ExecStart` and `ExecStop`, use the
+following `cap` commands in dry-run mode, and update from the above forking
+service configuration accordingly. Note also that the configured `User` should
+likely be the same as the capistrano3-puma `:puma_user` option.
 
 ~~~~ sh
 stage=production # or different stage, as needed