bin/: Use explicit "--" separator for assert-arg usages

In order to prevent legitimate cases to fail as errors, such as:

  NUM='-10'
  eval "$(assert-arg "$NUM" '-n NUM')"

To prevent assert-arg(1) from treating "-10" as the options "-1 and -0,
they need to be put after the "--" separator.

This way, all usages of assert-arg(1) that had its first argument as a
variable were adapted, and the usage and examples of assert-arg itself
were updated to encourage this best practice.

1 files changed, 3 insertions, 3 deletions

diff --git a/bin/vm b/bin/vm
index bfd182a..2296f72 100755
--- a/bin/vm
+++ b/bin/vm
@@ -214,7 +214,7 @@ write_ssh_config
 ACTION="${1:-}"
 OS="${2:-}"
 
-eval "$(assert-arg "$ACTION" 'ACTION')"
+eval "$(assert-arg -- "$ACTION" 'ACTION')"
 shift
 
 
@@ -247,7 +247,7 @@ case "$ACTION" in
 		done
 		;;
 	up)
-		eval "$(assert-arg "$OS" 'OS')"
+		eval "$(assert-arg -- "$OS" 'OS')"
 		shift
 		if [ "${1:-}" = '--' ]; then
 			shift
@@ -301,7 +301,7 @@ case "$ACTION" in
 		write_ssh_config
 		;;
 	down)
-		eval "$(assert-arg "$OS" 'OS')"
+		eval "$(assert-arg -- "$OS" 'OS')"
 		shift
 		if [ "${1:-}" = '--' ]; then
 			shift