cmdWorker

cmdWorker

cmdWorker is the Golang library wrapping github.com/go-cmd/cmd adding timeouts,periodic output parsing using callback function and ability to abort command execution from output parsing callback function.

cmdWorker should not be used for console commands with huge output because go-cmd is used in buffering mode storing all stdout and stderr output in a memory

Three configurable timeouts is supoorted:

var (
	DefTimeout      = time.Second * 120 //timeout the cmd must finished
	DefReadTimeout  = time.Second * 30  //timeout waiting new data from stdout/stderr
	DefReadInterval = time.Second * 1   //the interval outputHandler is called to process the output
)

cw := cmdWorker.NewCmdWorker(cmdPath, []string{}, readStdout)
status, err := cw.Run(nil)

if err != nil {
    if err == cmdWorker.ErrOperation {
      fmt.Printf("%v finished with error %v", status.Cmd, status.Exit)
    } else if _, ok := err.(*cmdWorker.InterruptedError); ok {
      fmt.printf("%v interrupted")
    }
}

Do a file downloading using curl with progress processing

readStdout := func(status cmdWorker.OutputStatus) bool {
        //regexp to parse the curl progress line (we need the second number)
		progressRegexp := regexp.MustCompile(`^\d+\s+(\d+)`)
		
		if len(status.newStderrLines) == 0 {
			return true
		}
		//get the last line from the output removing leading \r
		l := strings.TrimPrefix(status.newStderrLines[len(status.newStderrLines)-1], "\r")
		matches := progressRegexp.FindStringSubmatchIndex(l)
		if len(matches) > 0 {
			s := string(progressRegexp.ExpandString(nil, "$1", l, matches))
			fmt.Printf("Downloaded %v bytes\n", s)
		}
		return true
	}

//download the www.google.com index page using curl with a speed limit of 2kb/s to demonstrate long time stdout parsing
cw := cmdWorker.NewCmdWorker("curl", []string{"www.google.com", "--limit-rate", "2000", "-o", "/dev/null"}, readStdout)
status, err := cw.Run(nil)

if err != nil {
    if err == cmdWorker.ErrOperation {
        fmt.Printf("%v finished with error %v", status.Cmd, status.Exit)
    } else if _, ok := err.(*InterruptedError); ok {
        fmt.Printf("%v interrupted", status.Cmd)
    }
}

fmt.Printf("%v finished", status.Cmd)