The big difference is that Upstart looks for defined events to start anything. So if you want to add your own service, you need to figure out in which context you need your service.
Usually this is easy since you will want something that runs, for example, on your desktop. The desktop starts with event runlevel 5, so you set that in your script. For systemd, in contrast, this is the graphical target. In upstart, you also have other events you can use such as mounting, mounted and keyboard request. These are handled with systemd through sockets and dbus.
The scripts are not executable, they just point to one executable or more that should be run. In any Upstart scripts, you have defined on which event the script should start and when it should stop. You should also have pre-start and post-stop entries. These will prepare the environment and clean up after execution.
A sample script is below. The start and stop directives defines when the script will start automatically. As you can see, you can also set the directory it will run in. There are many more aspects to Upstart but you should learn how to migrate out. Here you can see that the same things happen but with other keywords. The format is simple and to the point. Instead of having runlevels, you point at which target wants your script.
Is it performing some function for some logged in user, specific to them? Does it not need a user logged in do its work, or need to run when the system starts? Improve this answer. Do you know why this is? RyanStull the service command deals exclusively with system jobs and sysvinit scripts.
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This line starts with exec to indicate that the following commands should be run through the Bash shell:. Notice this echo command uses backticks to run date as a command and then write the entire message to a log file. If any issues are detected, this command will indicate the specific line number and the problem.
However, with the test job you should see output like this:. This command can be used for controlling Upstart jobs and other background services, such as a web server. This command will read out the file into the shell; you should see a single line similar to the one below:. You should see a second line in the log displaying a later timestamp to confirm it ran as an Upstart job.
This merely scratches the surface of what you can do with Upstart. Regardless of its type, a job is always defined in a configuration file. Each of these jobs has a goal — to start or stop. Between these two goals are a set of task states, which define the current actions of the job in regards to the goal.
The important states are as follows:. After the post-start state, the job is defined as running. It stays running until a pre-stop is triggered, where the job gets ready to stop, then the job is killed and the post-stop cleanup procedures take place, if defined.
Remember that states are not events, and events are not states. This will demonstrate how you can transition from running basic test configurations to production-ready scripts. Covered briefly in the introduction, a service job involves scripting configuration files that allow processes to run in the background. To get started, go ahead and install it on your cloud server. First things first. Start by entering the job description and author lines to define the configuration.
We want this Node-powered server application to start when the server is up and running and to stop when it shuts down gracefully. Because of this, make sure to specify both conditions:. Remember the runlevel criteria from earlier? Combined with the filesystem event, this will ensure that the job loads when the server is up and running normally.
Pre-start and pre-stop are job states, but they also work in stanzas. What this means is that different commands can be run based on the state the job is in. However, the first stanza to write is the job script itself. This will get a process ID for the Node background server and then run the application script.
Note the indentation of commands inside a stanza — this is essential for syntactically correct formatting. The date, along with a starting or stopping message will be appended to a log file for our job:. Notice that the pre-stop stanza contains another line: removing the PID file as part of the procedure for shutting down the server what pre-stop does.
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