Add content for startup management (#1581)

content/roadmaps/102-devops/content/101-os-concepts/108-startup-management.md

@@ -1 +1,10 @@
-# Startup management
+# Startup Management (init.d)
+
+`init.d` is a daemon which is the **first process** (PID = 1) of the Linux system. Then other processes, services, daemons, and threads are started by init. One can write their own scripts in *'/etc/init.d'* location to start services automatically on system boot. Services can be started and stopped manually by using `service` command.
+
+It has following syntax: `$ service [service_name] [action]` e.g. `$ service ssh start`
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.freecodecamp.org/news/the-linux-booting-process-6-steps-described-in-detail/'>Linux Booting Process</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.geeksforgeeks.org/what-is-init-d-in-linux-service-management/'>What is init.d?</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://itsfoss.com/linux-daemons/'>What are Daemons in Linux?</BadgeLink>