wall initial implementation - #578

src/uu/wall/Cargo.toml:19

• The nix dependency enables a feature named "feature", which doesn’t appear to be used elsewhere in this workspace and is likely not a valid nix crate feature; this can cause Cargo feature resolution failures.

chrono = { workspace = true }
clap.workspace = true
nix = { workspace = true, features = ["feature", "fs", "hostname", "term"] }
thiserror.workspace = true

src/uu/wall/src/wall.rs:40

• WallError::Stdin is used via #[from] io::Error, so file-open/read errors also get reported as "cannot read stdin". Consider using a more general message so file input failures aren’t mislabeled.

enum WallError {
    #[error("wall: cannot read stdin")]
    Stdin(#[from] io::Error),
    #[error("wall: encoding error")]

src/uu/wall/src/wall.rs:58

• handle_clap_result(...).map_err(|e| USimpleError::new(1, ...)) forces exit code 1 for clap’s help/version output and other parsing errors. Other utilities in this repo rely on try_get_matches_from(args)? so clap/help uses the expected exit codes.

pub fn uumain(args: impl uucore::Args) -> UResult<()> {
    let matches = uucore::clap_localization::handle_clap_result(uu_app(), args)
        .map_err(|e| USimpleError::new(1, e.to_string()))?; // Clap would have return 101
    // Might be considered wrong for --help and --version
    let message = get_message(matches.get_many(STRING).unwrap_or_default())?;

src/uu/wall/src/wall.rs:122

• Same as the Linux cfg: prefer Command::new(uucore::util_name()) to follow the established pattern across utilities and keep the displayed name consistent.

pub fn uu_app() -> Command {
    Command::new("wall")
        .version(uucore::crate_version!())

src/uu/wall/src/wall.rs:101

• Typo in user-facing help text: "branner" → "banner".

                .required(false)
                .action(ArgAction::SetTrue)
                .help("Suppress the intro branner of the broadcast"),
        )

src/uu/wall/src/wall.rs:133

• Same user-facing help text issue here (ungrammatical).

                .value_name("GROUP")
                .help("Send restrict to only users in the group(s)")
                .num_args(1)

src/uu/wall/src/wall.rs:218

• On macOS the broadcast header format string is missing the closing ")" after the datetime, which makes the output inconsistent with Linux and likely incorrect.

        "\r\nBroadcast message from {}@{} ({tty}) at ({datetime} \r\n\r\n",

tests/by-util/test_wall.rs:24

• This test doesn’t assert anything, so it may not actually execute the command (unlike the other tests in this directory which call .succeeds()/.fails()). Add an explicit expectation so the test verifies behavior on Linux.

fn test_invalid_file() {
    new_ucmd!().arg("not_existing_file.not_existing_extension"); // Should print non-file name as broadcast
}