add JSON error parsing and highlighting

README.md

@@ -22,7 +22,6 @@ installed and a config exists, simply run
 watchmod
 ```
 
-
 For system wide install with Go:
 
 ```sh
@@ -89,6 +88,30 @@ will result in it's exclusion.
               exit, instead of running in daemon mode and listening for changes.   
 
 
+# JSON Errors
+If command output is JSON, watchmod print the error if the JSON has the field
+"success" with the bool false and/or the field "error" with a not nil value. (If
+command output is not JSON it is not parsed.)
+
+Command output that includes JSON of
+
+```JSON
+{"success":false} 
+
+```
+Or
+```JSON
+{"error":"call had an error"}
+```
+
+Results in a log like the following:
+
+```sh
+2023/05/23 13:58:52 ⚠️ watchmod command error: test/echo_error_test.sh
+{"success":false,"foo":"bar",...}
+```
+
+
 # Notes
 - Expands environmental vars in flags and config file.  
 - Config support JSON5 for comments and trailing commas.  Alternatively, config

test/echo_error_test.sh

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+echo '{"success":false}'

watchmod.go

@@ -25,7 +25,7 @@ type flags struct {
 	Daemon     bool
 }
 
-type Config struct { // Config options setable by config file.
+type Config struct { // Config options settable by config file.
 	WatchCommand   map[string]string
 	ExcludeFiles   []string
 	ExcludeStrings []string
@@ -141,18 +141,38 @@ func Watch(dir, cmd string) {
 	<-done
 }
 
+// jError is for parsing errors from JSON.  If JSON, check for error by looking
+// for `"success":false` and field "error" not nil.  i.e.
+//
+// {"success":false,"msg":"call had an error","path":"/admin/job/minPage"} Or
+// {"error":"call had an error","path":"/admin/job/minPage"}
+type jError struct {
+	Success bool            `json:"success,omitempty" `
+	Err     json.RawMessage `json:"error,omitempty" `
+}
+
 func runCmd(cmd string) {
 	log.Printf("Start run %q\n", cmd)
 	start := time.Now()
 
 	commandOut := exec.Command(cmd)
 	stdoutStderr, err := commandOut.CombinedOutput()
 	if err != nil {
-		log.Printf("watchmod error: %s; On cmd: %s; Error: \n%s\n", err, cmd, stdoutStderr)
+		// See "fatih/color" for color codes: https://github.com/fatih/color/blob/f4c431696a22e834b83444f720bd144b2dbbccff/color.go#L64
+		log.Printf("\x1b[31m⚠️ watchmod error:\x1b[0m  %s; On cmd: %s; Error: \n%s\n", err, cmd, stdoutStderr)
 	} else if C.PrintStdOut && len(stdoutStderr) != 0 {
 		log.Printf("%s", stdoutStderr)
 	}
 
+	// Check for JSON errors.
+	je := new(jError)
+	err = json.Unmarshal(stdoutStderr, je)
+	if err == nil { // Ignore errors assuming command output is not JSON.
+		if je.Success == false || len(je.Err) != 0 {
+			log.Printf("\x1b[31m⚠️ watchmod command error:\x1b[0m %s\n%s\n\n", cmd, stdoutStderr)
+		}
+	}
+
 	elapsed := time.Since(start)
 	log.Printf("End   run %q in %s\n", cmd, elapsed)
 }

watchmod.json5

@@ -1,11 +1,12 @@
 // This is a test watch config.  
 // Do testing with: 
-// `go run watchmod.go`
+// `go test`
 
 {
 	"WatchCommand":{
-	"$WATCHMOD":"$WATCHMOD/example.sh",
-	"$WATCHMOD/test":"$WATCHMOD/example.sh",
+	"$WATCHMOD":"$WATCHMOD/test/example.sh",
+	"$WATCHMOD/test":"$WATCHMOD/test/example.sh",
+	"$WATCHMOD":"$WATCHMOD/test/echo_error_test.sh",
 	},
 	"ExcludeFiles":[
 		"app.min.js",