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, 1 insertions, 1 deletions

diff --git a/bin/lines b/bin/lines
index 2f0bf46..6cda6f0 100755
--- a/bin/lines
+++ b/bin/lines
@@ -76,6 +76,6 @@ else
 	END=$(($2 - START + 1))
 fi
 
-eval "$(assert-arg "$START" 'START')"
+eval "$(assert-arg -- "$START" 'START')"
 
 tail -n +"$START" | head -n "$END"