-is unset, or if the history file is unwritable, the history is not saved.
-After saving the history, the history file is truncated
-to contain no more than @env{$HISTFILESIZE} lines.
-If @env{HISTFILESIZE} is unset, or set to null, a non-numeric value, or
-a numeric value less than zero, the history file is not truncated.
+is unset, or if the history file is unwritable, the history is
+not saved. After saving the history, the history file is truncated
+to contain no more than @env{$HISTFILESIZE}
+lines. If @env{HISTFILESIZE} is not set, no truncation is performed.