From 117ab372be230570a36c5d65e75a6689e2190943 Mon Sep 17 00:00:00 2001
From: Joey Gibson <joey@joeygibson.com>
Date: Sat, 23 Jan 2021 00:32:45 -0500
Subject: [PATCH] made head and tail mutually exclusive

---
 README.md | 2 +-
 main.go   | 9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index c32f2df..c93cc6e 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ A tool to count the rows, and take rows from  [Vertica native binary files](http
 ## Usage
 
 ```bash
-Usage: verticat [-cfHv] [-h value] [-o value] [-t value] [parameters ...]
+Usage: verticat [-cfHv] [-h value] [-o value] [-t value] <file>
  -c, --count       count rows
  -f, --force       force overwrite of output file
  -h, --head=value  take the first n rows
diff --git a/main.go b/main.go
index 27f11d1..f26324f 100644
--- a/main.go
+++ b/main.go
@@ -25,6 +25,7 @@ func main() {
 
 	getopt.SetParameters("<file>")
 	getopt.Parse()
+
 	args := getopt.Args()
 
 	if *helpFlag {
@@ -46,7 +47,13 @@ func main() {
 	}
 
 	if len(args) == 0 {
-		_, _ = fmt.Fprintln(os.Stderr, "no file given")
+		_, _ = fmt.Fprintf(os.Stderr, "Error: no file given\n\n")
+		getopt.PrintUsage(os.Stderr)
+		os.Exit(1)
+	}
+
+	if *headRows > 0 && *tailRows > 0 {
+		fmt.Fprintf(os.Stderr, "Error: --head and --tail are mutually exclusive\n\n")
 		getopt.PrintUsage(os.Stderr)
 		os.Exit(1)
 	}