Handle Ctrl+C (Signal Interrupt) Close in the Terminal

· 372 words · 2 minutes read
#os #signal #interrupt #sigterm #sigint #goroutine #channel #ctrl+c

When running a Go program in the terminal, your program could receive a signal interrupt from the OS for any number of reasons. One of which is if the user presses Ctrl+C on their keyboard (or whatever your operating system/terminal is set to). We can execute some code when this interrupt is received, mainly to clean up and reset what we were working on.

In our example we use a goroutine to listen for the interrupt from signal.Notify() (part of the signal package) and execute our clean up code when one is sent.

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package main

import (
	"fmt"
	"os"
	"os/signal"
	"syscall"
	"time"
)

const FileNameExample = "go-example.txt"

func main() {

	// Setup our Ctrl+C handler
	SetupCloseHandler()

	// Run our program... We create a file to clean up then sleep
	CreateFile()
	for {
		fmt.Println("- Sleeping")
		time.Sleep(10 * time.Second)
	}
}

// SetupCloseHandler creates a 'listener' on a new goroutine which will notify the
// program if it receives an interrupt from the OS. We then handle this by calling
// our clean up procedure and exiting the program.
func SetupCloseHandler() {
	c := make(chan os.Signal)
	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
	go func() {
		<-c
		fmt.Println("\r- Ctrl+C pressed in Terminal")
		DeleteFiles()
		os.Exit(0)
	}()
}

// DeleteFiles is used to simulate a 'clean up' function to run on shutdown. Because
// it's just an example it doesn't have any error handling.
func DeleteFiles() {
	fmt.Println("- Run Clean Up - Delete Our Example File")
	_ = os.Remove(FileNameExample)
	fmt.Println("- Good bye!")
}

// Create a file so we have something to clean up when we close our program.
func CreateFile() {
	fmt.Println("- Create Our Example File")
	file, _ := os.Create(FileNameExample)
	defer file.Close()
}

This will output:

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$ go run sigint.go 
- Create Our Example File
- Sleeping
- Ctrl+C pressed in Terminal
- Run Clean Up - Delete Our Example File
- Good bye!

And here’s what it looks like:

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Author:  Edd Turtle

Edd is the Lead Developer at Hoowla, a prop-tech startup, where he spends much of his time working on production-ready Go and PHP code. He loves coding, but also enjoys cycling and camping in his spare time.

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