fix path. add notes to help install protoc

main.go

@@ -6,6 +6,7 @@ package main
 import (
 	"errors"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/alexflint/go-arg"
@@ -51,8 +52,10 @@ func main() {
 		os.Exit(-1)
 	}
 
+	// todo, look for go.work files
 	if argv.GoSrc == "" {
-		argv.GoSrc = "/home/jcarr/go/src"
+		homeDir, _ := os.UserHomeDir()
+		argv.GoSrc = filepath.Join(homeDir, "go/src")
 	}
 
 	if argv.GoPath == "" {

protoc.go

@@ -4,10 +4,12 @@ package main
 
 import (
 	"errors"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
 
+	"github.com/go-cmd/cmd"
 	"go.wit.com/lib/gui/shell"
 	"go.wit.com/log"
 )
@@ -88,6 +90,33 @@ func protocBuild(names map[string]string) error {
 	for i, s := range cmd {
 		log.Info("\t", i, s)
 	}
-	shell.PathRun(argv.GoSrc, cmd)
+	return runprotoc(argv.GoSrc, cmd)
+}
+
+func runprotoc(pwd string, mycmd []string) error {
+	result := shell.PathRun(argv.GoSrc, mycmd)
+	if result.Error != nil {
+		return userNotes(result)
+	}
+	if result.Exit != 0 {
+		return userNotes(result)
+	}
 	return nil
 }
+
+func userNotes(result cmd.Status) error {
+	log.Info("protoc failed", result.Cmd, "with", result.Exit)
+	for _, line := range result.Stdout {
+		log.Info("STDOUT:", line)
+	}
+	for _, line := range result.Stderr {
+		log.Info("STDERR:", line)
+	}
+	log.Info("This is likely because you don't have protoc and protoc-gen-go installed")
+	log.Info("")
+	log.Info("On debian, you can:")
+	log.Info("   apt install protobuf-compiler   # for protoc")
+	log.Info("   apt install protoc-gen-go       # for protoc-gen-go")
+	log.Info("")
+	return fmt.Errorf("protoc failed with %d %v", result.Exit, result.Error)
+}