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, 2 insertions, 2 deletions

diff --git a/bin/grun b/bin/grun
index 74d8819..e9cfebe 100755
--- a/bin/grun
+++ b/bin/grun
@@ -72,7 +72,7 @@ done
 shift $((OPTIND - 1))
 
 FILENAME="${1:-}"
-eval "$(assert-arg "$FILENAME" 'FILENAME')"
+eval "$(assert-arg -- "$FILENAME" 'FILENAME')"
 shift
 
 if [ "${1:-}" != '--' ]; then
@@ -82,7 +82,7 @@ if [ "${1:-}" != '--' ]; then
 fi
 shift
 
-eval "$(assert-arg "${1:-}" 'COMMAND')"
+eval "$(assert-arg -- "${1:-}" 'COMMAND')"
 
 
 if [ ! -e "$FILENAME" ]; then