func Command(command string, args ...string) Filter {
	return FilterFunc(func(arg Arg) error {
		cmd := exec.Command(command, args...)
		input, err := cmd.StdinPipe()
		if err != nil {
			return err
		}
		output, err := cmd.StdoutPipe()
		if err != nil {
			return err
		}
		if err := cmd.Start(); err != nil {
			return err
		}
		var ierr error // Records error writing to command input
		var wg sync.WaitGroup
		wg.Add(1)
		go func() {
			defer wg.Done()
			for s := range arg.In {
				_, ierr = fmt.Fprintln(input, s)
				if ierr != nil {
					input.Close()
					return
				}
			}
			ierr = input.Close()
		}()
		if err := splitIntoLines(output, arg); err != nil {
			wg.Wait()
			cmd.Wait()
			return err
		}
		err = cmd.Wait()
		wg.Wait()
		if err != nil {
			return err
		}
		return ierr
	})
}
func Command(command string, args ...string) Filter {
	return FilterFunc(func(arg Arg) error {
		cmd := exec.Command(command, args...)
		input, err := cmd.StdinPipe()
		if err != nil {
			return err
		}
		output, err := cmd.StdoutPipe()
		if err != nil {
			return err
		}
		if err := cmd.Start(); err != nil {
			return err
		}
		var ierr error 
		var wg sync.WaitGroup
		wg.Add(1)
		go func() {
			defer wg.Done()
			for s := range arg.In {
				_, ierr = fmt.Fprintln(input, s)
				if ierr != nil {
					input.Close()
					return
				}
			}
			ierr = input.Close()
		}()
		if err := splitIntoLines(output, arg); err != nil {
			wg.Wait()
			cmd.Wait()
			return err
		}
		err = cmd.Wait()
		wg.Wait()
		if err != nil {
			return err
		}
		return ierr
	})
}
func Command ( command string , args ... string ) Filter { return FilterFunc ( func ( arg Arg ) error { cmd := exec . Command ( command , args ... ) input , err := cmd . StdinPipe ( ) if err != nil { return err } output , err := cmd . StdoutPipe ( ) if err != nil { return err } if err := cmd . Start ( ) ; err != nil { return err } var ierr error // Records error writing to command input var wg sync . WaitGroup wg . Add ( 1 ) go func ( ) { defer wg . Done ( ) for s := range arg . In { _ , ierr = fmt . Fprintln ( input , s ) if ierr != nil { input . Close ( ) return } } ierr = input . Close ( ) } ( ) if err := splitIntoLines ( output , arg ) ; err != nil { wg . Wait ( ) cmd . Wait ( ) return err } err = cmd . Wait ( ) wg . Wait ( ) if err != nil { return err } return ierr } ) }
// Command executes "command args...".
//
// The filter's input items are fed as standard input to the command,
// one line per input item. The standard output of the command is
// split into lines and the lines form the output of the filter (with
// trailing newlines removed).
Command executes command args ... . The filter s input items are fed as standard input to the command one line per input item . The standard output of the command is split into lines and the lines form the output of the filter ( with trailing newlines removed ) .