Update systemctl.md; add page of systemd-analyze (#844)

pages/linux/systemctl.md

@@ -6,9 +6,9 @@
 
 `systemctl --failed`
 
-- Start/Stop/Restart a service:
+- Start/Stop/Restart/Reload a service:
 
-`systemctl start/stop/restart {{unit}}`
+`systemctl start/stop/restart/reload {{unit}}`
 
 - Show the status of a unit:
 
@@ -18,6 +18,10 @@
 
 `systemctl enable/disable {{unit}}`
 
+- Mask/Unmask a unit, prevent it to be started on bootup:
+
+`systemctl mask/unmask {{unit}}`
+
 - Reload systemd, scanning for new or changed units:
 
 `systemctl daemon-reload`

pages/linux/systemd-analyze.md

@@ -0,0 +1,11 @@
+# systemd-analyze
+
+> Show timing details about the boot process of units (services, mount points, devices, sockets).
+
+- List time of each unit to start up:
+
+`systemd-analyze blame`
+
+- Print a tree of the time critical chain of units:
+
+`systemd-analyze critical-chain`