When passing a directory or a non-executable file as the program to run to kitty open it with the shell, instead of just failing.

Allows using kitty as the program to open directories or shell scripts
from desktop environments.

docs/changelog.rst

@@ -42,6 +42,9 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 
 - Double clicking on empty tab bar area now opens a new tab (:iss:`3201`)
 
+- When passing a directory or a non-executable file as the program to run to
+  kitty open it with the shell, instead of just failing.
+
 - Linux: Fix rendering of emoji followed by the graphics variation selector not
   being colored with some fonts (:iss:`3211`)
 

kitty/tabs.py

@@ -2,6 +2,8 @@
 # vim:fileencoding=utf-8
 # License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 
+import os
+import stat
 import weakref
 from collections import deque
 from contextlib import suppress
@@ -15,7 +17,7 @@ from typing import (
 from .borders import Borders
 from .child import Child
 from .cli_stub import CLIOptions
-from .constants import appname
+from .constants import appname, kitty_exe
 from .fast_data_types import (
     add_tab, attach_window, detach_window, get_boss, mark_tab_bar_dirty,
     next_window_id, remove_tab, remove_window, ring_bell, set_active_tab,
@@ -277,11 +279,43 @@ class Tab:  # {{{
         env: Optional[Dict[str, str]] = None,
         allow_remote_control: bool = False
     ) -> Child:
+        check_for_suitability = True
         if cmd is None:
             if use_shell:
                 cmd = resolved_shell(self.opts)
+                check_for_suitability = False
             else:
+                if self.args.args:
+                    cmd = list(self.args.args)
+                else:
+                    cmd = resolved_shell(self.opts)
+                    check_for_suitability = False
                 cmd = self.args.args or resolved_shell(self.opts)
+        if check_for_suitability:
+            old_exe = cmd[0]
+            try:
+                is_executable = os.access(old_exe, os.X_OK)
+            except OSError:
+                pass
+            else:
+                try:
+                    st = os.stat(old_exe)
+                except OSError:
+                    pass
+                else:
+                    if stat.S_ISDIR(st.st_mode):
+                        cwd = old_exe
+                        cmd = resolved_shell(self.opts)
+                    elif not is_executable:
+                        import shlex
+                        with suppress(OSError):
+                            with open(old_exe) as f:
+                                cmd = [kitty_exe(), '+hold']
+                                if f.read(2) == '#!':
+                                    line = f.read(4096).splitlines()[0]
+                                    cmd += shlex.split(line) + [old_exe]
+                                else:
+                                    cmd += [resolved_shell(self.opts)[0], cmd[0]]
         fenv: Dict[str, str] = {}
         if env:
             fenv.update(env)