shell: empty HISTFILE disables history saving, just as unset one did

The rationale here is that unsetting HISTFILE in /etc/profile
does not "stick": if it's unset, the default one is set later
(after /etc/profile is executed) by the shell.
But setting (and exporting, so it is inherited by all
(grand)child shells) an empty one works.

function                                             old     new   delta
save_history                                         296     316     +20

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 18344767a..1a85eec71 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -14540,7 +14540,7 @@ exitshell(void)
                 /* HISTFILE: "If unset, the command history is not saved when a shell exits." */
                 hp = lookupvar("HISTFILE");
                 line_input_state->hist_file = hp;
-                save_history(line_input_state); /* no-op if hist_file is NULL */
+                save_history(line_input_state); /* no-op if hist_file is NULL or "" */
         }
 #endif
 
diff --git a/shell/hush.c b/shell/hush.c
index 68aca53a3..0b2bc01f5 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2120,7 +2120,7 @@ static void hush_exit(int exitcode)
                 /* HISTFILE: "If unset, the command history is not saved when a shell exits." */
                 hp = get_local_var_value("HISTFILE");
                 G.line_input_state->hist_file = hp;
-                save_history(G.line_input_state); /* no-op if hist_file is NULL */
+                save_history(G.line_input_state); /* no-op if hist_file is NULL or "" */
         }
 #endif