Better documentation

1 files changed, 13 insertions, 4 deletions

diff --git a/hi.go b/hi.go
index ec927b3..7d3370a 100644
--- a/hi.go
+++ b/hi.go
@@ -90,16 +90,16 @@ func (c *colorFlag) String() string {
 func run() error {
 	args := flag.Args()
 	if len(args) == 0 {
-		fmt.Fprintf(os.Stderr, "missing regexp to highlight\n")
+		fmt.Fprintf(os.Stderr, "hi: missing regexp to highlight\n")
 		flag.Usage()
 	}
 	if len(args) > 2 {
-		fmt.Fprintf(os.Stderr, "too many positional arguments\n")
+		fmt.Fprintf(os.Stderr, "hi: too many positional arguments\n")
 		flag.Usage()
 	}
 	highlightRE, err := regexp.CompilePOSIX(args[0])
 	if err != nil {
-		return fmt.Errorf("invalid highlight regexp: %s", err)
+		return fmt.Errorf("invalid highlight regexp: %s\n", err)
 	}
 	foregroundColor := highlightColor.Foreground()
 	backgroundColor := background.Background()
@@ -119,8 +119,17 @@ func run() error {
 
 func main() {
 	flag.Usage = func() {
-		fmt.Fprintf(os.Stderr, "Usage: hi [OPTIONS] REGEXP\n")
+		fmt.Fprintf(os.Stderr, `Usage: hi [OPTION]... REGEXP
+Highlight lines from standard input using the given regexp.
+
+`)
 		flag.PrintDefaults()
+		fmt.Fprintf(os.Stderr, `
+Examples:
+  echo 1\n2\n3 | hi ^2
+
+  journalctl | hi -bg cyan (E|e)rror | less
+`)
 		os.Exit(2)
 	}
 	flag.Parse()