add help flag to commands

Display command usage using the '--help' flag.

1 files changed, 9 insertions, 2 deletions

diff --git a/cmd/installpkg/main.go b/cmd/installpkg/main.go
index 5cc4955..009a2e7 100644
--- a/cmd/installpkg/main.go
+++ b/cmd/installpkg/main.go
@@ -44,6 +44,10 @@ import (
 //                    the previous package's files, and this will catch the few
 //                    corner cases without generating unnecessary writes.
 
+func usage() {
+	getopt.PrintUsage(os.Stdout)
+}
+
 func ParseFlags() *pkgtools.InstallPkgFlags {
 	flags := pkgtools.DefaultInstallPkgFlags
 	flags.SetEnvValues()
@@ -56,9 +60,12 @@ func ParseFlags() *pkgtools.InstallPkgFlags {
 }
 
 func main() {
+	getopt.SetParameters("package_filename ...")
+	help := getopt.BoolLong("help", 0, "display help")
+
 	flags := ParseFlags()
-	if len(getopt.Args()) == 0 {
-		getopt.PrintUsage(os.Stdout)
+	if len(getopt.Args()) == 0 || *help {
+		usage()
 		return
 	}