If you look at Nginx it calls "nginx reload" to reload itself. Is there any way to send a signal from the command line to a running process? Even if the main process starts child processes how can I send commands to the main to notify its children?
ex:
myapp start -debug // starts a server
myapp reload -gracefull // stops the app gracefully
Now i need to send os signals to notify my server to perform a graceful shutdown
kill -QUIT pid
kill -USR2 pid
I hope my question is clear enough Thnx
Take a look at the os/signal
package.
Package signal implements access to incoming signals.
There is even an example in the documentation :
// Set up channel on which to send signal notifications.
// We must use a buffered channel or risk missing the signal
// if we're not ready to receive when the signal is sent.
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt, os.Kill)
// Block until a signal is received.
s := <-c
fmt.Println("Got signal:", s)
To see how to send signals take a look at signal_test.go
, it uses syscall
. For example :
// Send this process a SIGHUP
t.Logf("sighup...")
syscall.Kill(syscall.Getpid(), syscall.SIGHUP)
waitSig(t, c, syscall.SIGHUP)
I figured out that in go i we can pass the environment to syscall.Exec
err := syscall.Exec(argv0. os.Args. os.Environ())
simply copies the current env to the child process.
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