Fix broken crontab installation

cmd/persist-user-crontab-reboot/main.go

@@ -33,13 +33,13 @@ func main() {
 		log.Fatalf("copy: %v", err)
 	}
 
-	install := fmt.Sprintf(`(crontab -l | egrep -v "%s"); echo @reboot "%s") | crontab)`, dest, dest)
+	install := fmt.Sprintf(`( crontab -l | egrep -v "%s"; echo @reboot "%s" ) | crontab`, dest, dest)
 	if err := iexec.WithTimeout(10*time.Second, "sh", "-c", install); err != nil {
 		log.Fatalf("crontab install failed: %v", err)
 	}
 
 	defer func() {
-		remove := fmt.Sprintf(`(crontab -l | egrep -v "%s") | crontab)`, dest)
+		remove := fmt.Sprintf(`crontab -l | egrep -v "%s" | crontab`, dest)
 		if err := iexec.WithTimeout(10*time.Second, "sh", "-c", remove); err != nil {
 			log.Fatalf("crontab remove failed: %v", err)
 		}

pkg/iexec/iexec.go

@@ -3,6 +3,7 @@ package iexec
 import (
 	"context"
 	"errors"
+	"fmt"
 	"log"
 	"os"
 	"os/exec"
@@ -21,7 +22,7 @@ func WithTimeout(timeout time.Duration, program string, args ...string) error {
 			log.Printf("hit my %s time limit, have a wonderful day! ...", timeout)
 			return nil
 		}
-		return err
+		return fmt.Errorf("cmd: %v\n%s", err, bs)
 	}
 
 	log.Printf("output: %s", bs)