"nvim -es": disable shada #21723

Problem:
`nvim -es` (and `nvim -Es`) is the recommended way to non-interactively
run commands/vimscript. But it enables shada by default, which is
usually not wanted.

Solution:
- Disable shada by default for `nvim -es/-Es`. This can be overridden by
  `-i foo` if needed.
- Do NOT change the 'loadplugins' default.
  - User config + packages _should_ be enabled by default, for both `nvim
    -es` and `nvim -l`. Else any Lua packages you have can't be accessed
    without `-u path/to/config`, which is clumsy.
      - Use-cases:
        ```
        nvim --headless "+Lazy! sync" +qa
            would become: nvim -es "+Lazy! sync"
        nvim --headless +PlugInstall +qall
            would become: nvim -es +PlugInstall
        ```
  - Opt-out (`--clean` or `-u NONE`) is much easier than opt-in (`-u
    path/to/config`).
  -  User config/packages are analogous to pip packages, which are
     expected when doing `python -c ...`.

related: 7c94bcd2d77e2e54b8836ab8325460a367b79eae
related: ddd0eb6f5120a09b97867d2561ea61309038ccd2

7 files changed, 58 insertions, 25 deletions

diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt
index b7c5a50443..6547a76f56 100644
--- a/runtime/doc/lua.txt
+++ b/runtime/doc/lua.txt
@@ -618,20 +618,20 @@ Example: TCP echo-server                                          *tcp-server*
 Multithreading                                            *lua-loop-threading*
 
 Plugins can perform work in separate (os-level) threads using the threading
-APIs in luv, for instance `vim.uv.new_thread`. Note that every thread
-gets its own separate Lua interpreter state, with no access to Lua globals
-in the main thread. Neither can the state of the editor (buffers, windows,
-etc) be directly accessed from threads.
+APIs in luv, for instance `vim.uv.new_thread`. Each thread has its own
+separate Lua interpreter state, with no access to Lua globals on the main
+thread. Neither can the editor state (buffers, windows, etc) be directly
+accessed from threads.
 
-A subset of the `vim.*` API is available in threads. This includes:
+A subset of the `vim.*` stdlib is available in threads, including:
 
 - `vim.uv` with a separate event loop per thread.
 - `vim.mpack` and `vim.json` (useful for serializing messages between threads)
 - `require` in threads can use Lua packages from the global |package.path|
 - `print()` and `vim.inspect`
 - `vim.diff`
-- most utility functions in `vim.*` for working with pure Lua values
-  like `vim.split`, `vim.tbl_*`, `vim.list_*`, and so on.
+- Most utility functions in `vim.*` that work with pure Lua values, like
+  `vim.split`, `vim.tbl_*`, `vim.list_*`, etc.
 - `vim.is_thread()` returns true from a non-main thread.
 
 
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index d573b01baa..b7606e65f5 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -295,6 +295,7 @@ PLUGINS
 
 STARTUP
 
+• |-es| ("script mode") disables shada by default.
 • Nvim will fail if the |--listen| or |$NVIM_LISTEN_ADDRESS| address is
   invalid, instead of silently skipping an invalid address.
 
diff --git a/runtime/doc/starting.txt b/runtime/doc/starting.txt
index 3b0fa2b371..0bfbea75fb 100644
--- a/runtime/doc/starting.txt
+++ b/runtime/doc/starting.txt
@@ -207,12 +207,12 @@ argument.
 			:print
 			:set
 		With |:verbose| or 'verbose', other commands display on stderr: >
-			nvim -es +":verbose echo 'foo'"
-			nvim -V1 -es +foo
-
-<		User |config| is skipped unless |-u| was given.
-		Swap file is skipped (like |-n|).
-		User |shada| is loaded (unless "-i NONE" is given).
+			nvim -es +"verbose echo 'foo'"
+			nvim -V1 -es +"echo 'foo'"
+<
+		Skips user |config| unless |-u| was given.
+		Disables |shada| unless |-i| was given.
+		Disables swapfile (like |-n|).
 
 							*-l*
 -l {script} [args]
@@ -235,6 +235,11 @@ argument.
 			nvim +q -l foo.lua
 <		This loads Lua module "bar" before executing "foo.lua": >
 			nvim +"lua require('bar')" -l foo.lua
+<								    *lua-shebang*
+		You can set the "shebang" of the script so that Nvim executes
+		the script when called with "./" from a shell (remember to
+		"chmod u+x"): >
+			#!/usr/bin/env -S nvim -l
 <
 		Skips user |config| unless |-u| was given.
 		Disables plugins unless 'loadplugins' was set.
@@ -243,7 +248,7 @@ argument.
 
 							*-ll*
 -ll {script} [args]
-		Execute a Lua script, similarly to |-l|, but the editor is not
+		Executes a Lua script, similarly to |-l|, but the editor is not
 		initialized. This gives a Lua environment similar to a worker
 		thread. See |lua-loop-threading|.
 
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index 9f28b373ee..a92ddf33e6 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -409,6 +409,8 @@ Startup:
 - |-es| and |-Es| have improved behavior:
     - Quits automatically, don't need "-c qa!".
     - Skips swap-file dialog.
+    - Optimized for non-interactive scripts: disables swapfile, shada.
+- |-l| Executes Lua scripts non-interactively.
 - |-s| reads Normal commands from stdin if the script name is "-".
 - Reading text (instead of commands) from stdin |--|:
     - works by default: "-" file is optional
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 2b55a48c12..58d110e8b2 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -1228,6 +1228,9 @@ static void command_line_scan(mparm_T *parmp)
         if (exmode_active) {    // "-es" silent (batch) Ex-mode
           silent_mode = true;
           parmp->no_swap_file = true;
+          if (p_shadafile == NULL || *p_shadafile == NUL) {
+            set_option_value_give_err(kOptShadafile, STATIC_CSTR_AS_OPTVAL("NONE"), 0);
+          }
         } else {                // "-s {scriptin}" read from script file
           want_argument = true;
         }
@@ -2085,8 +2088,7 @@ static void source_startup_scripts(const mparm_T *const parmp)
 {
   // If -u given, use only the initializations from that file and nothing else.
   if (parmp->use_vimrc != NULL) {
-    if (strequal(parmp->use_vimrc, "NONE")
-        || strequal(parmp->use_vimrc, "NORC")) {
+    if (strequal(parmp->use_vimrc, "NONE") || strequal(parmp->use_vimrc, "NORC")) {
       // Do nothing.
     } else {
       if (do_source(parmp->use_vimrc, false, DOSO_NONE, NULL) != OK) {
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 661d0754d4..d45bc147cb 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -2719,7 +2719,7 @@ static msgchunk_T *disp_sb_line(int row, msgchunk_T *smp)
 }
 
 /// @return  true when messages should be printed to stdout/stderr:
-///          - "batch mode" ("silent mode", -es/-Es)
+///          - "batch mode" ("silent mode", -es/-Es/-l)
 ///          - no UI and not embedded
 int msg_use_printf(void)
 {
diff --git a/test/functional/core/startup_spec.lua b/test/functional/core/startup_spec.lua
index 642e2b0287..8ecd3dca97 100644
--- a/test/functional/core/startup_spec.lua
+++ b/test/functional/core/startup_spec.lua
@@ -136,7 +136,11 @@ describe('startup', function()
       vim.list_extend(args, { '-l', (script or 'test/functional/fixtures/startup.lua') })
       vim.list_extend(args, lua_args or {})
       local out = fn.system(args, input):gsub('\r\n', '\n')
-      return eq(dedent(expected), out)
+      if type(expected) == 'function' then
+        return expected(out)
+      else
+        return eq(dedent(expected), out)
+      end
     end
 
     it('failure modes', function()
@@ -172,6 +176,7 @@ describe('startup', function()
     it('Lua-error sets Nvim exitcode', function()
       local proc = n.spawn_wait('-l', 'test/functional/fixtures/startup-fail.lua')
       matches('E5113: .* my pearls!!', proc:output())
+      eq(0, proc.signal)
       eq(1, proc.status)
 
       eq(0, eval('v:shell_error'))
@@ -282,14 +287,30 @@ describe('startup', function()
       eq(0, eval('v:shell_error'))
     end)
 
-    it('disables swapfile/shada/config/plugins', function()
+    it('disables swapfile/shada/config/plugins unless overridden', function()
+      local script = [[print(('updatecount=%d shadafile=%s loadplugins=%s scripts=%d'):format(
+                       vim.o.updatecount, vim.o.shadafile, tostring(vim.o.loadplugins), math.max(1, #vim.fn.getscriptinfo())))]]
+      finally(function()
+        os.remove('Xtest_shada')
+      end)
+
       assert_l_out(
         'updatecount=0 shadafile=NONE loadplugins=false scripts=1\n',
         nil,
         nil,
         '-',
-        [[print(('updatecount=%d shadafile=%s loadplugins=%s scripts=%d'):format(
-          vim.o.updatecount, vim.o.shadafile, tostring(vim.o.loadplugins), math.max(1, #vim.fn.getscriptinfo())))]]
+        script
+      )
+
+      -- User can override.
+      assert_l_out(
+        function(out)
+          return matches('updatecount=99 shadafile=Xtest_shada loadplugins=true scripts=2%d\n', out)
+        end,
+        { '+set updatecount=99', '-i', 'Xtest_shada', '+set loadplugins', '-u', 'NORC' },
+        nil,
+        '-',
+        script
       )
     end)
   end)
@@ -572,19 +593,21 @@ describe('startup', function()
     eq('  encoding=utf-8\n', fn.system({ nvim_prog, '-n', '-es' }, { 'set encoding', '' }))
   end)
 
-  it('-es/-Es disables swapfile, user config #8540', function()
+  it('-es/-Es disables swapfile/shada/config #8540', function()
     for _, arg in ipairs({ '-es', '-Es' }) do
       local out = fn.system({
         nvim_prog,
         arg,
-        '+set swapfile? updatecount? shadafile?',
+        '+set updatecount? shadafile? loadplugins?',
         '+put =map(getscriptinfo(), {-> v:val.name})',
         '+%print',
       })
       local line1 = string.match(out, '^.-\n')
       -- updatecount=0 means swapfile was disabled.
-      eq('  swapfile  updatecount=0  shadafile=\n', line1)
-      -- Standard plugins were loaded, but not user config.
+      eq('  updatecount=0  shadafile=NONE  loadplugins\n', line1)
+      -- Standard plugins were loaded, but not user config. #31878
+      local nrlines = #vim.split(out, '\n')
+      ok(nrlines > 20, '>20', nrlines)
       ok(string.find(out, 'man.lua') ~= nil)
       ok(string.find(out, 'init.vim') == nil)
     end