feat: add GNU ls compatibility mode

README.md

@@ -25,6 +25,7 @@ with time! 😁
 - [Usage](#usage)
   - [Fuzzy Time](#fuzzy-time)
   - [Icons](#icons)
+  - [Compatibility Mode](#compatibility-mode)
   - [Configuration File](#configuration-file)
   - [Aliases](#aliases)
 - [Development](#development)
@@ -139,6 +140,44 @@ a Pull Request implementing it! 😁
 
 You can disable the icons by using the `--no-icons` option.
 
+### Compatibility Mode
+
+`lsp` has two CLI modes:
+
+- `native` - the default `lsplus` command-line interface
+- `gnu` - a GNU `ls` compatibility mode intended for aliases and scripts
+
+You can enable GNU compatibility mode in either of these ways:
+
+```toml
+compat_mode = "gnu"
+```
+
+or:
+
+```sh
+LSP_COMPAT_MODE=gnu lsp
+```
+
+The `LSP_COMPAT_MODE` environment variable takes precedence over the config
+file.
+
+At the moment, compatibility mode only changes the CLI surface and help output.
+It does not yet implement the missing GNU meanings for the conflicting short
+flags `-D`, `-I`, `-N`, and `-Z`; those flags are reserved in `gnu` mode and
+will error until their GNU behavior is implemented.
+
+The current `lsplus` features behind those four native short flags are still
+available in `gnu` mode through their long forms only:
+
+- `--group-directories-first` (replaces the original `--sort-dirs`)
+- `--gitignore`
+- `--no-color`
+- `--fuzzy-time`
+
+In `gnu` mode, `-p` uses the GNU-style long form `--indicator-style=slash`
+instead of the native `--slash-dirs`.
+
 ### Configuration File
 
 You can set options using the configuration file so they will apply to every run
@@ -154,6 +193,10 @@ The `lsp` command can be aliased to `ls` by adding the following line to your
 alias ls='lsp'
 ```
 
+If you want that alias to behave more like GNU `ls`, enable `gnu`
+compatibility mode in your config file or set `LSP_COMPAT_MODE=gnu` in your
+shell environment.
+
 You will need to restart your shell or source your configuration file for the
 alias to take effect.
 

TODO.md

@@ -9,6 +9,12 @@
 - [ ] using the config file, allow extending the existing file and folder
       mapping, or deleting specific maps.
 - [ ] add a -R flag to recursively list files in a directory.
+- [ ] Rework short-mode file indicators so symlinks use `@` independently of
+      `-p`, and implement the remaining GNU-style indicator modes together,
+      including their preferred GNU short forms where they exist
+      (`--indicator-style=file-type` / `--file-type`,
+      `--indicator-style=classify` / `-F`, and
+      `--indicator-style=none`).
 - [ ] When adding recursion or tree-style output, revisit whether directory
       traversal should move over to the `ignore` crate instead of the current
       custom walker.

docs/src/config.md

@@ -10,11 +10,27 @@ location:
 The configuration file is optional and if it is not found, `lsplus` will use the
 default settings.
 
+`lsplus` also supports an `LSP_COMPAT_MODE` environment variable. When set, it
+overrides the `compat_mode` value from the config file.
+
 ## Available Options
 
 The following options are available in the configuration file and correspond to
 the relevant command line options:
 
+### compat_mode
+
+- Permitted values: `"native"` or `"gnu"`
+- Default value: `"native"`
+
+This option selects which command-line interface `lsp` uses at startup.
+`native` keeps the standard `lsplus` CLI, while `gnu` enables the GNU `ls`
+compatibility surface intended for aliases and scripts.
+
+At the moment, `gnu` mode changes the CLI surface and help output only. The
+conflicting GNU short flags `-D`, `-I`, `-N`, and `-Z` are reserved in that
+mode and will error until their GNU behavior is implemented.
+
 ### show_all
 
 - Permitted values: `true` or `false`
@@ -38,14 +54,18 @@ will display all files and directories if set to `true`, except for `.` and
 - Default value: `false`
 
 This option corresponds to the `-p` or `--slash-dirs` command line option and
-will append a slash to directories if set to `true`.
+will append a slash to directories if set to `true`. In `gnu` compatibility
+mode, the equivalent long option is `--indicator-style=slash`.
 
 ### dirs_first
 
 - Permitted values: `true` or `false`
 - Default value: `false`
 
-This option corresponds to the `--sort-dirs` command line option and will
+This option corresponds to the `--sort-dirs` command line option and will sort
+directories before files when set to `true`. In `gnu` compatibility mode, the
+equivalent long option is `--group-directories-first` (replacing the original
+`--sort-dirs`).
 
 ### long_format
 
@@ -103,6 +123,7 @@ The following is an example configuration file that sets several options. Any
 options that are not set will use the default values:
 
 ```toml
+# compat_mode = "native"  # or "gnu" for GNU ls compatibility
 show_all = true
 append_slash = true
 dirs_first = true

docs/src/usage.md

@@ -39,6 +39,33 @@ When `-I` is enabled, `lsp` checks the same ignore sources Git normally uses:
 merged `.gitignore` files in the worktree, `.git/info/exclude`, and the
 configured global Git excludes file.
 
+## Compatibility Mode
+
+`lsp` has two CLI modes:
+
+- `native` - the default `lsplus` command-line interface
+- `gnu` - a GNU `ls` compatibility mode intended for aliases and scripts
+
+You can enable GNU compatibility mode by setting `compat_mode = "gnu"` in the
+config file or by setting `LSP_COMPAT_MODE=gnu` in the environment. The
+environment variable takes precedence over the config file.
+
+At the moment, `gnu` mode changes the CLI surface and help output only. It does
+not yet implement the missing GNU meanings for the conflicting short flags
+`-D`, `-I`, `-N`, and `-Z`; those flags are reserved in `gnu` mode and will
+error until their GNU behavior is implemented.
+
+The current `lsplus` features behind those four native short flags are still
+available in `gnu` mode through their long forms only:
+
+- `--group-directories-first` (replaces the original `--sort-dirs`)
+- `--gitignore`
+- `--no-color`
+- `--fuzzy-time`
+
+In `gnu` mode, `-p` uses the GNU-style long form `--indicator-style=slash`
+instead of the native `--slash-dirs`.
+
 ## Fuzzy Time
 
 The `-Z` option will show a fuzzy time for file modification times. This will
@@ -64,6 +91,10 @@ The `lsp` command can be aliased to `ls` by adding the following line to your
 alias ls='lsp'
 ```
 
+If you want that alias to behave more like GNU `ls`, enable `gnu`
+compatibility mode in your config file or set `LSP_COMPAT_MODE=gnu` in your
+shell environment.
+
 You will need to restart your shell or source your configuration file for the
 alias to take effect.
 
@@ -80,6 +111,7 @@ You can also use the configuration file to set the default options you want.
 
 ![lsp output](./images/screenshot.png)
 
-If you add the '-D' option to the command, directories will be sorted first:
+If you add the `-D` option to the command (native mode only; use
+`--group-directories-first` in gnu mode), directories will be sorted first:
 
 ![lsp output](./images/screenshot2.png)

src/app.rs

@@ -8,9 +8,21 @@ use crate::settings;
 use crate::utils;
 use crate::utils::file::collect_file_info;
 
+/// Run `lsplus` using parsed CLI flags and config loaded from disk.
 pub fn run_with_flags(args: cli::Flags) -> io::Result<()> {
     let config = settings::load_config();
-    let params = Params::merge(&args, &config);
+    run_with_flags_and_config(args, &config)
+}
+
+/// Run `lsplus` using parsed CLI flags and an explicit config value.
+///
+/// This is primarily useful in tests and library-style entry points that want
+/// to inject config without relying on filesystem state.
+pub fn run_with_flags_and_config(
+    args: cli::Flags,
+    config: &Params,
+) -> io::Result<()> {
+    let params = Params::merge(&args, config);
     utils::color::configure_color_output(&params);
     let patterns = patterns_from_args(args.paths);