nologin: Add tool

src/uu/nologin/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "uu_nologin"
+version = "0.0.1"
+edition = "2021"
+
+[lib]
+path = "src/nologin.rs"
+
+[[bin]]
+name = "nologin"
+path = "src/main.rs"
+
+[dependencies]
+uucore = { workspace = true }
+clap = { workspace = true }

src/uu/nologin/nologin.md

@@ -0,0 +1,7 @@
+# nologin
+
+```
+nologin [options]
+```
+
+Politely refuse a login.

src/uu/nologin/src/main.rs

@@ -0,0 +1 @@
+uucore::bin!(uu_nologin);

src/uu/nologin/src/nologin.rs

@@ -0,0 +1,91 @@
+// This file is part of the uutils util-linux package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use clap::{crate_version, Arg, ArgAction, Command};
+use std::fs;
+use uucore::{error::UResult, format_usage, help_about, help_usage};
+
+const ABOUT: &str = help_about!("nologin.md");
+const USAGE: &str = help_usage!("nologin.md");
+
+#[uucore::main]
+pub fn uumain(args: impl uucore::Args) -> UResult<()> {
+    let _matches = uu_app().try_get_matches_from(args)?;
+
+    // Try to read custom message from /etc/nologin.txt
+    let message = match fs::read_to_string("/etc/nologin.txt") {
+        Ok(content) => content.trim().to_string(),
+        Err(_) => "This account is currently not available.".to_string(),
+    };
+
+    println!("{}", message);
+    std::process::exit(1);
+}
+
+pub fn uu_app() -> Command {
+    Command::new(uucore::util_name())
+        .version(crate_version!())
+        .about(ABOUT)
+        .override_usage(format_usage(USAGE))
+        .infer_long_args(true)
+        .arg(
+            Arg::new("command")
+                .short('c')
+                .long("command")
+                .value_name("command")
+                .help("does nothing (for compatibility)"),
+        )
+        .arg(
+            Arg::new("init-file")
+                .long("init-file")
+                .value_name("file")
+                .help("does nothing (for compatibility)"),
+        )
+        .arg(
+            Arg::new("interactive")
+                .short('i')
+                .long("interactive")
+                .help("does nothing (for compatibility)")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("login")
+                .short('l')
+                .long("login")
+                .help("does nothing (for compatibility)")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("noprofile")
+                .long("noprofile")
+                .help("does nothing (for compatibility)")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("norc")
+                .long("norc")
+                .help("does nothing (for compatibility)")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("posix")
+                .long("posix")
+                .help("does nothing (for compatibility)")
+                .action(ArgAction::SetTrue),
+        )
+        .arg(
+            Arg::new("rcfile")
+                .long("rcfile")
+                .value_name("file")
+                .help("does nothing (for compatibility)"),
+        )
+        .arg(
+            Arg::new("restricted")
+                .short('r')
+                .long("restricted")
+                .help("does nothing (for compatibility)")
+                .action(ArgAction::SetTrue),
+        )
+}