config: add "initial-command" config, "-e" sets that

Fixes #2601

It is more expected behavior that `-e` affects only the first window. By
introducing a dedicated configuration we avoid making `-e` too magical:
its simply syntax sugar for setting the "initial-command" configuration.

src/App.zig

@@ -66,6 +66,11 @@ font_grid_set: font.SharedGridSet,
 last_notification_time: ?std.time.Instant = null,
 last_notification_digest: u64 = 0,
 
+/// Set to false once we've created at least one surface. This
+/// never goes true again. This can be used by surfaces to determine
+/// if they are the first surface.
+first: bool = true,
+
 pub const CreateError = Allocator.Error || font.SharedGridSet.InitError;
 
 /// Initialize the main app instance. This creates the main window, sets

src/Surface.zig

@@ -474,13 +474,19 @@ pub fn init(
         .config = derived_config,
     };
 
+    // The command we're going to execute
+    const command: ?[]const u8 = if (app.first)
+        config.@"initial-command" orelse config.command
+    else
+        config.command;
+
     // Start our IO implementation
     // This separate block ({}) is important because our errdefers must
     // be scoped here to be valid.
     {
         // Initialize our IO backend
         var io_exec = try termio.Exec.init(alloc, .{
-            .command = config.command,
+            .command = command,
             .shell_integration = config.@"shell-integration",
             .shell_integration_features = config.@"shell-integration-features",
             .working_directory = config.@"working-directory",
@@ -618,9 +624,9 @@ pub fn init(
         // For xdg-terminal-exec execution we special-case and set the window
         // title to the command being executed. This allows window managers
         // to set custom styling based on the command being executed.
-        const command = config.command orelse break :xdg;
-        if (command.len > 0) {
-            const title = alloc.dupeZ(u8, command) catch |err| {
+        const v = command orelse break :xdg;
+        if (v.len > 0) {
+            const title = alloc.dupeZ(u8, v) catch |err| {
                 log.warn(
                     "error copying command for title, title will not be set err={}",
                     .{err},
@@ -635,6 +641,9 @@ pub fn init(
             );
         }
     }
+
+    // We are no longer the first surface
+    app.first = false;
 }
 
 pub fn deinit(self: *Surface) void {

src/config/Config.zig

@@ -513,7 +513,26 @@ palette: Palette = .{},
 /// arguments are provided, the command will be executed using `/bin/sh -c`.
 /// Ghostty does not do any shell command parsing.
 ///
-/// If you're using the `ghostty` CLI there is also a shortcut to run a command
+/// This command will be used for all new terminal surfaces, i.e. new windows,
+/// tabs, etc. If you want to run a command only for the first terminal surface
+/// created when Ghostty starts, use the `initial-command` configuration.
+///
+/// Ghostty supports the common `-e` flag for executing a command with
+/// arguments. For example, `ghostty -e fish --with --custom --args`.
+/// This flag sets the `initial-command` configuration, see that for more
+/// information.
+command: ?[]const u8 = null,
+
+/// This is the same as "command", but only applies to the first terminal
+/// surface created when Ghostty starts. Subsequent terminal surfaces will use
+/// the `command` configuration.
+///
+/// After the first terminal surface is created (or closed), there is no
+/// way to run this initial command again automatically. As such, setting
+/// this at runtime works but will only affect the next terminal surface
+/// if it is the first one ever created.
+///
+/// If you're using the `ghostty` CLI there is also a shortcut to set this
 /// with arguments directly: you can use the `-e` flag. For example: `ghostty -e
 /// fish --with --custom --args`. The `-e` flag automatically forces some
 /// other behaviors as well:
@@ -525,7 +544,7 @@ palette: Palette = .{},
 ///     process will exit when the command exits. Additionally, the
 ///     `quit-after-last-window-closed-delay` is unset.
 ///
-command: ?[]const u8 = null,
+@"initial-command": ?[]const u8 = null,
 
 /// If true, keep the terminal open after the command exits. Normally, the
 /// terminal window closes when the running command (such as a shell) exits.
@@ -2356,7 +2375,7 @@ pub fn loadCliArgs(self: *Config, alloc_gpa: Allocator) !void {
             }
 
             self.@"_xdg-terminal-exec" = true;
-            self.command = command.items[0 .. command.items.len - 1];
+            self.@"initial-command" = command.items[0 .. command.items.len - 1];
             return;
         }
     }
@@ -2755,7 +2774,7 @@ pub fn parseManuallyHook(
             return false;
         }
 
-        self.command = command.items[0 .. command.items.len - 1];
+        self.@"initial-command" = command.items[0 .. command.items.len - 1];
 
         // See "command" docs for the implied configurations and why.
         self.@"gtk-single-instance" = .false;
@@ -2945,7 +2964,7 @@ test "parse e: command only" {
 
     var it: TestIterator = .{ .data = &.{"foo"} };
     try testing.expect(!try cfg.parseManuallyHook(alloc, "-e", &it));
-    try testing.expectEqualStrings("foo", cfg.command.?);
+    try testing.expectEqualStrings("foo", cfg.@"initial-command".?);
 }
 
 test "parse e: command and args" {
@@ -2956,7 +2975,7 @@ test "parse e: command and args" {
 
     var it: TestIterator = .{ .data = &.{ "echo", "foo", "bar baz" } };
     try testing.expect(!try cfg.parseManuallyHook(alloc, "-e", &it));
-    try testing.expectEqualStrings("echo foo bar baz", cfg.command.?);
+    try testing.expectEqualStrings("echo foo bar baz", cfg.@"initial-command".?);
 }
 
 test "clone default" {