Customizable error message prefix

command.go

@@ -181,6 +181,9 @@ type Command struct {
 	// versionTemplate is the version template defined by user.
 	versionTemplate string
 
+	// errPrefix is the error message prefix defined by user.
+	errPrefix string
+
 	// inReader is a reader defined by the user that replaces stdin
 	inReader io.Reader
 	// outWriter is a writer defined by the user that replaces stdout
@@ -346,6 +349,11 @@ func (c *Command) SetVersionTemplate(s string) {
 	c.versionTemplate = s
 }
 
+// SetErrPrefix sets error message prefix to be used. Application can use it to set custom prefix.
+func (c *Command) SetErrPrefix(s string) {
+	c.errPrefix = s
+}
+
 // SetGlobalNormalizationFunc sets a normalization function to all flag sets and also to child commands.
 // The user should not have a cyclic dependency on commands.
 func (c *Command) SetGlobalNormalizationFunc(n func(f *flag.FlagSet, name string) flag.NormalizedName) {
@@ -1050,7 +1058,7 @@ func (c *Command) ExecuteC() (cmd *Command, err error) {
 			c = cmd
 		}
 		if !c.SilenceErrors {
-			c.PrintErrln("Error:", err.Error())
+			c.PrintErrln(c.errPrefix, err.Error())
 			c.PrintErrf("Run '%v --help' for usage.\n", c.CommandPath())
 		}
 		return c, err
@@ -1079,7 +1087,7 @@ func (c *Command) ExecuteC() (cmd *Command, err error) {
 		// If root command has SilenceErrors flagged,
 		// all subcommands should respect it
 		if !cmd.SilenceErrors && !c.SilenceErrors {
-			c.PrintErrln("Error:", err.Error())
+			c.PrintErrln(c.errPrefix, err.Error())
 		}
 
 		// If root command has SilenceUsage flagged,