Is There a Reliable Way to Determine Process Existence in Go?

Determining Process Existence in Go using os.FindProcess

While using os.FindProcess can provide information about a process's existence, it's not entirely reliable for determining if a process has been terminated or killed.

Leveraging the Unix Approach

Traditionally, the Unix command kill -s 0 [PID] is employed to check if a process is still running. This approach sends a signal of 0 to the process, with no actual signal being sent. Instead, it serves as a way to verify the process's existence.

Implementation in Go

Translating this method into Go, the following code demonstrates how to determine if a process is still active:

import (
    "fmt"
    "log"
    "os"
    "os/exec"
    "strconv"
    "syscall"
)

func main() {
    for _, p := range os.Args[1:] {
        pid, err := strconv.ParseInt(p, 10, 64)
        if err != nil {
            log.Fatal(err)
        }
        process, err := os.FindProcess(int(pid))
        if err != nil {
            fmt.Printf("Failed to find process: %s\n", err)
        } else {
            err := process.Signal(syscall.Signal(0))
            fmt.Printf("process.Signal on pid %d returned: %v\n", pid, err)
        }
    }
}

Example Output

Running this code provides the following output, indicating the status of processes with different IDs:

$ ./kill 1 $$ 123
process.Signal on pid 1 returned: operation not permitted
process.Signal on pid 12606 returned: <nil>
process.Signal on pid 123 returned: no such process

• Process 1: Alive but not owned by the current user.
• Process 12606: Alive and owned by the current user.
• Process 123: Terminated or killed.

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