2.4 KiB
go-daemon
A Linux daemon runs continuously written in golang. Refer to ahenk-docs/dev for resources
This repo will be include two separate daemons. One of them is written with C language for understanding native daemon processes c-daemon . Other one is written in go for implement same deamon concepts to go language and using with native performance go-daemon
Summary - MakeUseOf
Usually daemons start on system startup and run continuously until the system shuts down. They do NOT send messages to the console or screen in any way.
It is not mandatory but daemon processes are usually named to end with the letter d
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Initial operations, such as reading configuration files or obtaining necessary system resources, must be performed before the process becomes a daemon
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A background running process is created with init as its parent process. For this purpose, a sub-process is forked from the init process first, and then the upper process is terminated with exit
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A new session should open by calling the setsid function, and the process should be disconnected from the terminal
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All open file descriptors inherited from the parent process are closed
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Standard input, output, and error messages are redirected to
/dev/null -
The working directory of the process must change
The operating system groups processes into session and process groups. Each session consists of process groups.
Processes receive their inputs and send their outputs to controlling terminal. A controlling terminal is associated with only one session at a time
A session and process groups in it have identification (ID) numbers; these identification numbers are the process identification numbers (PID) of the session and process group leaders. A child process shares the same group as its parent process
Creating a Daemon Process
c-daemon
To create a demon process, we need a background process whose parent process is init. In the code _daemon creates a child process and then kils the parent process. In this case, our new process will be a subprocess of init and will continue to run in background!