made head and tail mutually exclusive

joeygibson · Jan 23, 2021 · 117ab37 · 117ab37
1 parent 7a55640
commit 117ab37
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Showing 2 changed files with 9 additions and 2 deletions.
diff --git 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
@@ -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)
 	}