bzgl. deinem FIXME. Man kann sowas hier machen:

#!/nix/store/a4yw1svqqk4d8lhwinn9xp847zz9gfma-bash-4.4-p23/bin/bash -e
echo "*/upgrade -yes /nix/store/8dacn2cnqm4f5jm0cmc0fhb70yfzp59f-weechat-bin-env-3.2/bin/weechat" > /var/lib/weechat/weechat_fifo

Wenn du /upgrade verwenden willst für weechat kann ich folgenden Patch empfehlen:

diff --git a/src/core/wee-command.c b/src/core/wee-command.c
index 7e12712a8..1fc9c0519 100644
--- a/src/core/wee-command.c
+++ b/src/core/wee-command.c
@@ -6209,6 +6209,19 @@ COMMAND_CALLBACK(upgrade)
                     free (ptr_binary);
                     return WEECHAT_RC_OK;
                 }
+               if (weechat_argv0 == NULL) {
+                       gui_chat_printf(NULL,
+                                       "%sNixOS: weechat_argv0 is NULL",
+                                       gui_chat_prefix[GUI_CHAT_PREFIX_ERROR]);
+               }
+               if (weechat_argv0 && strcmp(ptr_binary, weechat_argv0) == 0) {
+                   gui_chat_printf (NULL,
+                                    "%sNixOS: Not upgrading. The binary is the same: \"%s\"",
+                                    gui_chat_prefix[GUI_CHAT_PREFIX_ERROR],
+                                    ptr_binary);
+                   free (ptr_binary);
+                   return WEECHAT_RC_OK;
+               }
             }
         }
     }

Damit kannst du mit nixos rebuilds weechat in-place upgraden ohne downtime

In reply to @andir:nixos.dev
Jörg Thalheim: hat es funktioniert?