feat: add cli option to dump default config

Closes: https://github.com/aristocratos/btop/issues/1394

README.md

@@ -1296,7 +1296,7 @@ Config and log files stored in `$XDG_CONFIG_HOME/btop` or `$HOME/.config/btop` f
 #### btop.conf: (auto generated if not found)
 
 ```bash
-#? Config file for btop v. 1.2.2
+#? Config file for btop v.1.4.5
 
 #* Name of a btop++/bpytop/bashtop formatted ".theme" file, "Default" and "TTY" for builtin themes.
 #* Themes should be placed in "../share/btop/themes" relative to binary or "$HOME/.config/btop/themes"
@@ -1325,6 +1325,9 @@ vim_keys = False
 #* Rounded corners on boxes, is ignored if TTY mode is ON.
 rounded_corners = True
 
+#* Use terminal synchronized output sequences to reduce flickering on supported terminals.
+terminal_sync = True
+
 #* Default symbols to use for graph creation, "braille", "block" or "tty".
 #* "braille" offers the highest resolution but might not be included in all fonts.
 #* "block" has half the resolution of braille but uses more common characters.
@@ -1345,10 +1348,10 @@ graph_symbol_net = "default"
 graph_symbol_proc = "default"
 
 #* Manually set which boxes to show. Available values are "cpu mem net proc" and "gpu0" through "gpu5", separate values with whitespace.
-shown_boxes = "proc cpu mem net"
+shown_boxes = "cpu mem net proc"
 
 #* Update time in milliseconds, recommended 2000 ms or above for better sample times for graphs.
-update_ms = 1500
+update_ms = 2000
 
 #* Processes sorting, "pid" "program" "arguments" "threads" "user" "memory" "cpu lazy" "cpu direct",
 #* "cpu lazy" sorts top process over time (easier to follow), "cpu direct" updates top process directly.
@@ -1367,13 +1370,13 @@ proc_colors = True
 proc_gradient = True
 
 #* If process cpu usage should be of the core it's running on or usage of the total available cpu power.
-proc_per_core = True
+proc_per_core = False
 
 #* Show process memory as bytes instead of percent.
 proc_mem_bytes = True
 
-#* Choose to preserve last cpu and memory usage of dead processes for when paused.
-keep_dead_proc_usage = False
+#* Show cpu graph for each process.
+proc_cpu_graphs = True
 
 #* Use /proc/[pid]/smaps for memory information in the process info box (very slow but more accurate)
 proc_info_smaps = False
@@ -1381,13 +1384,22 @@ proc_info_smaps = False
 #* Show proc box on left side of screen instead of right.
 proc_left = False
 
+#* (Linux) Filter processes tied to the Linux kernel(similar behavior to htop).
+proc_filter_kernel = False
+
+#* In tree-view, always accumulate child process resources in the parent process.
+proc_aggregate = False
+
+#* Should cpu and memory usage display be preserved for dead processes when paused.
+keep_dead_proc_usage = False
+
 #* Sets the CPU stat shown in upper half of the CPU graph, "total" is always available.
 #* Select from a list of detected attributes from the options menu.
-cpu_graph_upper = "total"
+cpu_graph_upper = "Auto"
 
 #* Sets the CPU stat shown in lower half of the CPU graph, "total" is always available.
 #* Select from a list of detected attributes from the options menu.
-cpu_graph_lower = "total"
+cpu_graph_lower = "Auto"
 
 #* Toggles if the lower CPU graph should be inverted.
 cpu_invert_lower = True
@@ -1433,7 +1445,7 @@ freq_mode = "first"
 
 #* Draw a clock at top of screen, formatting according to strftime, empty string to disable.
 #* Special formatting: /host = hostname | /user = username | /uptime = system uptime
-clock_format = "%H:%M"
+clock_format = "%X"
 
 #* Update main ui in background when menus are showing, set this to false if the menus is flickering too much for comfort.
 background_update = True
@@ -1442,8 +1454,8 @@ background_update = True
 custom_cpu_name = ""
 
 #* Optional filter for shown disks, should be full path of a mountpoint, separate multiple values with whitespace " ".
-#* Begin line with "exclude=" to change to exclude filter, otherwise defaults to "most include" filter. Example: disks_filter="exclude=/boot /home/user".
-disks_filter = "exclude=/boot"
+#* Only disks matching the filter will be shown. Prepend exclude= to only show disks not matching the filter. Examples: disk_filter="/boot /home/user", disks_filter="exclude=/boot /home/user"
+disks_filter = ""
 
 #* Show graphs instead of meters for memory values.
 mem_graphs = True
@@ -1467,7 +1479,10 @@ show_disks = True
 only_physical = True
 
 #* Read disks list from /etc/fstab. This also disables only_physical.
-use_fstab = False
+use_fstab = True
+
+#* Setting this to True will hide all datasets, and only show ZFS pools. (IO stats will be calculated per-pool)
+zfs_hide_datasets = False
 
 #* Set to true to show available disk space for privileged users.
 disk_free_priv = False
@@ -1494,10 +1509,13 @@ net_upload = 100
 net_auto = True
 
 #* Sync the auto scaling for download and upload to whichever currently has the highest scale.
-net_sync = False
+net_sync = True
 
 #* Starts with the Network Interface specified here.
-net_iface = "br0"
+net_iface = ""
+
+#* "True" shows bitrates in base 10 (Kbps, Mbps). "False" shows bitrates in binary sizes (Kibps, Mibps, etc.). "Auto" uses base_10_sizes.
+base_10_bitrate = "Auto"
 
 #* Show battery stats in top right if battery is present.
 show_battery = True
@@ -1505,9 +1523,13 @@ show_battery = True
 #* Which battery to use if multiple are present. "Auto" for auto detection.
 selected_battery = "Auto"
 
+#* Show power stats of battery next to charge indicator.
+show_battery_watts = True
+
 #* Set loglevel for "~/.config/btop/btop.log" levels are: "ERROR" "WARNING" "INFO" "DEBUG".
 #* The level set includes all lower levels, i.e. "DEBUG" will show all logging info.
-log_level = "DEBUG"
+log_level = "WARNING"
+
 ```
 
 #### Command line options
@@ -1525,6 +1547,7 @@ Options:
   -t, --tty               Force tty mode with ANSI graph symbols and 16 colors only
       --no-tty            Force disable tty mode
   -u, --update <ms>       Set an initial update rate in milliseconds
+      --default-config    Print default config to standard output
   -h, --help              Show this help message and exit
   -V, --version           Show a version message and exit (more with --version)
 ```

manpage.md

@@ -10,7 +10,7 @@ btop - Resource monitor that shows usage and stats for processor, memory, disks,
 
 **btop** [**-c**] [**-d**] [**-l**] [**-t**] [**-p** _id_] [**-u** _ms_] [**\-\-force-utf**] [**\-\-themes-dir** _dir_]
 
-**btop** [{**-h** | **\-\-help**} | {**-V** | **\-\-version**}]
+**btop** [**\-\-default-config** | {**-h** | **\-\-help**} | {**-V** | **\-\-version**}]
 
 # DESCRIPTION
 
@@ -51,6 +51,9 @@ starting with two dashes ('-'). A summary of options is included below.
 **-u**, **\-\-update _ms_**
 :   Set an initial update rate in milliseconds.
 
+**\-\-default-config**
+:   Print default config to standard output.
+
 **-h**, **\-\-help**
 :   Show summary of options.
 

src/btop_cli.cpp

@@ -5,15 +5,20 @@
 #include <algorithm>
 #include <expected>
 #include <filesystem>
+#include <iterator>
 #include <optional>
+#include <ranges>
 #include <span>
 #include <stdexcept>
 #include <string>
 #include <string_view>
 
+#include <unistd.h>
+
 #include <fmt/base.h>
 #include <fmt/format.h>
 
+#include "btop_config.hpp"
 #include "btop_shared.hpp"
 #include "config.h"
 
@@ -22,6 +27,9 @@ using namespace std::string_view_literals;
 static constexpr auto BOLD = "\033[1m"sv;
 static constexpr auto BOLD_UNDERLINE = "\033[1;4m"sv;
 static constexpr auto BOLD_RED = "\033[1;31m"sv;
+static constexpr auto BOLD_GREEN = "\033[1;32m"sv;
+static constexpr auto BOLD_YELLOW = "\033[1;33m"sv;
+static constexpr auto BOLD_BRIGHT_BLACK = "\033[1;90m"sv;
 static constexpr auto YELLOW = "\033[33m"sv;
 static constexpr auto RESET = "\033[0m"sv;
 
@@ -49,6 +57,9 @@ namespace Cli {
 		for (auto it = args.begin(); it != args.end(); ++it) {
 			auto arg = *it;
 
+			if (arg == "--default-config") {
+				return default_config();
+			}
 			if (arg == "-h" || arg == "--help") {
 				usage();
 				help();
@@ -187,6 +198,50 @@ namespace Cli {
 		return cli;
 	}
 
+	auto default_config() noexcept -> Result {
+		// The idea of using `current_config` is that the CLI parser is run before loading the actual config and thus
+		// provides default values.
+		auto config = Config::current_config();
+		
+		if (isatty(STDOUT_FILENO)) {
+			std::string buffer {};
+			// The config buffer ends in `\n`. `std::views::split` will then create an empty element after the last
+			// newline, which we would write as an additional empty line at the very end.
+			auto trimmed_config = config.substr(0, config.length() - 1);
+			for (const auto line : std::views::split(trimmed_config, '\n')) {
+				auto line_view = std::string_view { line };
+				if (line_view.starts_with("#")) {
+					fmt::format_to(
+						std::back_inserter(buffer), "{1}{0}{2}\n", line_view, BOLD_BRIGHT_BLACK, RESET
+					);
+				} else if (!line_view.empty()) {
+					auto pos = line_view.find("=");
+					if (pos == line_view.npos) {
+						error("invalid default config: '=' not found");
+						return std::unexpected { 1 };
+					}
+					auto name = line_view.substr(0, pos);
+					auto value = line_view.substr(pos + 1);
+					fmt::format_to(
+						std::back_inserter(buffer),
+						"{2}{0}{4}={3}{1}{4}\n",
+						name,
+						value,
+						BOLD_YELLOW,
+						BOLD_GREEN,
+						RESET
+					);
+				} else {
+					fmt::format_to(std::back_inserter(buffer), "\n");
+				}
+			}
+			fmt::print("{}", buffer);
+		} else {
+			fmt::print("{}", config);
+		}
+		return std::unexpected { 0 };
+	}
+
 	void usage() noexcept {
 		fmt::println("{0}Usage:{1} {2}btop{1} [OPTIONS]\n", BOLD_UNDERLINE, RESET, BOLD);
 	}
@@ -204,6 +259,7 @@ namespace Cli {
 			"  {2}    --themes-dir{1} <dir>  Path to a custom themes directory\n"
 			"  {2}    --no-tty{1}            Force disable tty mode\n"
 			"  {2}-u, --update{1} <ms>       Set an initial update rate in milliseconds\n"
+			"  {2}    --default-config{1}    Print default config to standard output\n"
 			"  {2}-h, --help{1}              Show this help message and exit\n"
 			"  {2}-V, --version{1}           Show a version message and exit (more with --version)\n",
 			BOLD_UNDERLINE, RESET, BOLD

src/btop_cli.hpp

@@ -39,6 +39,9 @@ namespace Cli {
 	// Parse the command line arguments
 	[[nodiscard]] auto parse(std::span<const std::string_view> args) noexcept -> Result;
 
+	// Print default config to standard output
+	[[nodiscard]] auto default_config() noexcept -> Result;
+
 	// Print a usage header
 	void usage() noexcept;
 

src/btop_config.cpp

@@ -20,12 +20,14 @@ tab-size = 4
 #include <atomic>
 #include <filesystem>
 #include <fstream>
+#include <iterator>
 #include <locale>
 #include <optional>
 #include <ranges>
 #include <string_view>
 #include <utility>
 
+#include <fmt/base.h>
 #include <fmt/core.h>
 #include <sys/statvfs.h>
 
@@ -782,20 +784,9 @@ namespace Config {
 		Logger::debug("Writing new config file");
 		if (geteuid() != Global::real_uid and seteuid(Global::real_uid) != 0) return;
 		std::ofstream cwrite(conf_file, std::ios::trunc);
-		cwrite.imbue(std::locale::classic());
+		// TODO: Report error when stream is in a bad state.
 		if (cwrite.good()) {
-			cwrite << "#? Config file for btop v. " << Global::Version << "\n";
-			for (const auto& [name, description] : descriptions) {
-				cwrite << "\n" << (description.empty() ? "" : description + "\n")
-						<< name << " = ";
-				if (strings.contains(name))
-					cwrite << "\"" << strings.at(name) << "\"";
-				else if (ints.contains(name))
-					cwrite << ints.at(name);
-				else if (bools.contains(name))
-					cwrite << (bools.at(name) ? "True" : "False");
-				cwrite << "\n";
-			}
+			cwrite << current_config();
 		}
 	}
 
@@ -828,4 +819,29 @@ namespace Config {
 	auto get_log_file() -> std::optional<fs::path> {
 		return get_xdg_state_dir().transform([](auto&& state_home) -> auto { return state_home / "btop.log"; });
 	}
+
+	auto current_config() -> std::string {
+		auto buffer = std::string {};
+		fmt::format_to(std::back_inserter(buffer), "#? Config file for btop v.{}\n", Global::Version);
+
+		for (const auto& [name, description] : descriptions) {
+			// Write a description comment if available.
+			fmt::format_to(std::back_inserter(buffer), "\n");
+			if (!description.empty()) {
+				fmt::format_to(std::back_inserter(buffer), "{}\n", description);
+			}
+
+			fmt::format_to(std::back_inserter(buffer), "{} = ", name);
+			// Lookup default value by name and write it out.
+			if (strings.contains(name)) {
+				fmt::format_to(std::back_inserter(buffer), R"("{}")", strings[name]);
+			} else if (ints.contains(name)) {
+				fmt::format_to(std::back_inserter(buffer), std::locale::classic(), "{:L}", ints[name]);
+			} else if (bools.contains(name)) {
+				fmt::format_to(std::back_inserter(buffer), "{}", bools[name] ? "True" : "False");
+			}
+			fmt::format_to(std::back_inserter(buffer), "\n");
+		}
+		return buffer;
+	}
 }

src/btop_config.hpp

@@ -132,4 +132,7 @@ namespace Config {
 	void write();
 
 	auto get_log_file() -> std::optional<std::filesystem::path>;
+
+	// Write default config to an in-memory buffer
+	[[nodiscard]] auto current_config() -> std::string;
 }