env: support string args by "-S", "-vS" or "--split-strings"

.vscode/cspell.dictionaries/shell.wordlist.txt

@@ -25,6 +25,7 @@ sudoedit
 tcsh
 tzselect
 urandom
+VARNAME
 wtmp
 zsh
 

Cargo.lock

@@ -547,7 +547,7 @@ dependencies = [
  "lazy_static",
  "proc-macro2",
  "regex",
- "syn 2.0.23",
+ "syn 2.0.32",
  "unicode-xid",
 ]
 
@@ -559,7 +559,7 @@ checksum = "3e1a2532e4ed4ea13031c13bc7bc0dbca4aae32df48e9d77f0d1e743179f2ea1"
 dependencies = [
  "lazy_static",
  "proc-macro2",
- "syn 2.0.23",
+ "syn 2.0.32",
 ]
 
 [[package]]
@@ -574,7 +574,7 @@ dependencies = [
  "lazy_static",
  "proc-macro2",
  "quote",
- "syn 2.0.23",
+ "syn 2.0.32",
 ]
 
 [[package]]
@@ -942,7 +942,7 @@ checksum = "89ca545a94061b6365f2c7355b4b32bd20df3ff95f02da9329b34ccc3bd6ee72"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.23",
+ "syn 2.0.32",
 ]
 
 [[package]]
@@ -1791,7 +1791,7 @@ dependencies = [
  "regex",
  "relative-path",
  "rustc_version",
- "syn 2.0.23",
+ "syn 2.0.32",
  "unicode-ident",
 ]
 
@@ -1902,9 +1902,23 @@ checksum = "e25dfac463d778e353db5be2449d1cce89bd6fd23c9f1ea21310ce6e5a1b29c4"
 
 [[package]]
 name = "serde"
-version = "1.0.147"
+version = "1.0.193"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d193d69bae983fc11a79df82342761dfbf28a99fc8d203dca4c3c1b590948965"
+checksum = "25dd9975e68d0cb5aa1120c288333fc98731bd1dd12f561e468ea4728c042b89"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.193"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43576ca501357b9b071ac53cdc7da8ef0cbd9493d8df094cd821777ea6e894d3"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.32",
+]
 
 [[package]]
 name = "sha1"
@@ -2039,9 +2053,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.23"
+version = "2.0.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "59fb7d6d8281a51045d62b8eb3a7d1ce347b76f312af50cd3dc0af39c87c1737"
+checksum = "239814284fd6f1a4ffe4ca893952cdd93c224b6a1571c9a9eadd670295c0c9e2"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -3296,7 +3310,7 @@ dependencies = [
  "once_cell",
  "proc-macro2",
  "quote",
- "syn 2.0.23",
+ "syn 2.0.32",
  "wasm-bindgen-shared",
 ]
 
@@ -3318,7 +3332,7 @@ checksum = "54681b18a46765f095758388f2d0cf16eb8d4169b639ab575a8f5693af210c7b"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.23",
+ "syn 2.0.32",
  "wasm-bindgen-backend",
  "wasm-bindgen-shared",
 ]

src/uu/env/src/native_int_str.rs

@@ -0,0 +1,325 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+// This module contains classes and functions for dealing with the differences
+// between operating systems regarding the lossless processing of OsStr/OsString.
+// In contrast to existing crates with similar purpose, this module does not use any
+// `unsafe` features or functions.
+// Due to a suboptimal design aspect of OsStr/OsString on windows, we need to
+// encode/decode to wide chars on windows operating system.
+// This prevents borrowing from OsStr on windows. Anyway, if optimally used,#
+// this conversion needs to be done only once in the beginning and at the end.
+
+use std::ffi::OsString;
+#[cfg(not(target_os = "windows"))]
+use std::os::unix::ffi::{OsStrExt, OsStringExt};
+#[cfg(target_os = "windows")]
+use std::os::windows::prelude::*;
+use std::{borrow::Cow, ffi::OsStr};
+
+#[cfg(target_os = "windows")]
+use u16 as NativeIntCharU;
+#[cfg(not(target_os = "windows"))]
+use u8 as NativeIntCharU;
+
+pub type NativeCharInt = NativeIntCharU;
+pub type NativeIntStr = [NativeCharInt];
+pub type NativeIntString = Vec<NativeCharInt>;
+
+pub struct NCvt;
+
+pub trait Convert<From, To> {
+    fn convert(f: From) -> To;
+}
+
+// ================ str/String =================
+
+impl<'a> Convert<&'a str, Cow<'a, NativeIntStr>> for NCvt {
+    fn convert(f: &'a str) -> Cow<'a, NativeIntStr> {
+        #[cfg(target_os = "windows")]
+        {
+            Cow::Owned(f.encode_utf16().collect())
+        }
+
+        #[cfg(not(target_os = "windows"))]
+        {
+            Cow::Borrowed(f.as_bytes())
+        }
+    }
+}
+
+impl<'a> Convert<&'a String, Cow<'a, NativeIntStr>> for NCvt {
+    fn convert(f: &'a String) -> Cow<'a, NativeIntStr> {
+        #[cfg(target_os = "windows")]
+        {
+            Cow::Owned(f.encode_utf16().collect())
+        }
+
+        #[cfg(not(target_os = "windows"))]
+        {
+            Cow::Borrowed(f.as_bytes())
+        }
+    }
+}
+
+impl<'a> Convert<String, Cow<'a, NativeIntStr>> for NCvt {
+    fn convert(f: String) -> Cow<'a, NativeIntStr> {
+        #[cfg(target_os = "windows")]
+        {
+            Cow::Owned(f.encode_utf16().collect())
+        }
+
+        #[cfg(not(target_os = "windows"))]
+        {
+            Cow::Owned(f.into_bytes())
+        }
+    }
+}
+
+// ================ OsStr/OsString =================
+
+impl<'a> Convert<&'a OsStr, Cow<'a, NativeIntStr>> for NCvt {
+    fn convert(f: &'a OsStr) -> Cow<'a, NativeIntStr> {
+        to_native_int_representation(f)
+    }
+}
+
+impl<'a> Convert<&'a OsString, Cow<'a, NativeIntStr>> for NCvt {
+    fn convert(f: &'a OsString) -> Cow<'a, NativeIntStr> {
+        to_native_int_representation(f)
+    }
+}
+
+impl<'a> Convert<OsString, Cow<'a, NativeIntStr>> for NCvt {
+    fn convert(f: OsString) -> Cow<'a, NativeIntStr> {
+        #[cfg(target_os = "windows")]
+        {
+            Cow::Owned(f.encode_wide().collect())
+        }
+
+        #[cfg(not(target_os = "windows"))]
+        {
+            Cow::Owned(f.into_vec())
+        }
+    }
+}
+
+// ================ Vec<Str/String> =================
+
+impl<'a> Convert<&'a Vec<&'a str>, Vec<Cow<'a, NativeIntStr>>> for NCvt {
+    fn convert(f: &'a Vec<&'a str>) -> Vec<Cow<'a, NativeIntStr>> {
+        f.iter().map(|x| Self::convert(*x)).collect()
+    }
+}
+
+impl<'a> Convert<Vec<&'a str>, Vec<Cow<'a, NativeIntStr>>> for NCvt {
+    fn convert(f: Vec<&'a str>) -> Vec<Cow<'a, NativeIntStr>> {
+        f.iter().map(|x| Self::convert(*x)).collect()
+    }
+}
+
+impl<'a> Convert<&'a Vec<String>, Vec<Cow<'a, NativeIntStr>>> for NCvt {
+    fn convert(f: &'a Vec<String>) -> Vec<Cow<'a, NativeIntStr>> {
+        f.iter().map(Self::convert).collect()
+    }
+}
+
+impl<'a> Convert<Vec<String>, Vec<Cow<'a, NativeIntStr>>> for NCvt {
+    fn convert(f: Vec<String>) -> Vec<Cow<'a, NativeIntStr>> {
+        f.into_iter().map(Self::convert).collect()
+    }
+}
+
+pub fn to_native_int_representation(input: &OsStr) -> Cow<'_, NativeIntStr> {
+    #[cfg(target_os = "windows")]
+    {
+        Cow::Owned(input.encode_wide().collect())
+    }
+
+    #[cfg(not(target_os = "windows"))]
+    {
+        Cow::Borrowed(input.as_bytes())
+    }
+}
+
+#[allow(clippy::needless_pass_by_value)] // needed on windows
+pub fn from_native_int_representation(input: Cow<'_, NativeIntStr>) -> Cow<'_, OsStr> {
+    #[cfg(target_os = "windows")]
+    {
+        Cow::Owned(OsString::from_wide(&input))
+    }
+
+    #[cfg(not(target_os = "windows"))]
+    {
+        match input {
+            Cow::Borrowed(borrow) => Cow::Borrowed(OsStr::from_bytes(borrow)),
+            Cow::Owned(own) => Cow::Owned(OsString::from_vec(own)),
+        }
+    }
+}
+
+#[allow(clippy::needless_pass_by_value)] // needed on windows
+pub fn from_native_int_representation_owned(input: NativeIntString) -> OsString {
+    #[cfg(target_os = "windows")]
+    {
+        OsString::from_wide(&input)
+    }
+
+    #[cfg(not(target_os = "windows"))]
+    {
+        OsString::from_vec(input)
+    }
+}
+
+pub fn get_single_native_int_value(c: &char) -> Option<NativeCharInt> {
+    #[cfg(target_os = "windows")]
+    {
+        let mut buf = [0u16, 0];
+        let s = c.encode_utf16(&mut buf);
+        if s.len() == 1 {
+            Some(buf[0])
+        } else {
+            None
+        }
+    }
+
+    #[cfg(not(target_os = "windows"))]
+    {
+        let mut buf = [0u8, 0, 0, 0];
+        let s = c.encode_utf8(&mut buf);
+        if s.len() == 1 {
+            Some(buf[0])
+        } else {
+            None
+        }
+    }
+}
+
+pub fn get_char_from_native_int(ni: NativeCharInt) -> Option<(char, NativeCharInt)> {
+    let c_opt;
+    #[cfg(target_os = "windows")]
+    {
+        c_opt = char::decode_utf16([ni; 1]).next().unwrap().ok();
+    };
+
+    #[cfg(not(target_os = "windows"))]
+    {
+        c_opt = std::str::from_utf8(&[ni; 1])
+            .ok()
+            .map(|x| x.chars().next().unwrap());
+    };
+
+    if let Some(c) = c_opt {
+        return Some((c, ni));
+    }
+
+    None
+}
+
+pub struct NativeStr<'a> {
+    native: Cow<'a, NativeIntStr>,
+}
+
+impl<'a> NativeStr<'a> {
+    pub fn new(str: &'a OsStr) -> Self {
+        Self {
+            native: to_native_int_representation(str),
+        }
+    }
+
+    pub fn native(&self) -> Cow<'a, NativeIntStr> {
+        self.native.clone()
+    }
+
+    pub fn into_native(self) -> Cow<'a, NativeIntStr> {
+        self.native
+    }
+
+    pub fn contains(&self, x: &char) -> Option<bool> {
+        let n_c = get_single_native_int_value(x)?;
+        Some(self.native.contains(&n_c))
+    }
+
+    pub fn slice(&self, from: usize, to: usize) -> Cow<'a, OsStr> {
+        let result = self.match_cow(|b| Ok::<_, ()>(&b[from..to]), |o| Ok(o[from..to].to_vec()));
+        result.unwrap()
+    }
+
+    pub fn split_once(&self, pred: &char) -> Option<(Cow<'a, OsStr>, Cow<'a, OsStr>)> {
+        let n_c = get_single_native_int_value(pred)?;
+        let p = self.native.iter().position(|&x| x == n_c)?;
+        let before = self.slice(0, p);
+        let after = self.slice(p + 1, self.native.len());
+        Some((before, after))
+    }
+
+    pub fn split_at(&self, pos: usize) -> (Cow<'a, OsStr>, Cow<'a, OsStr>) {
+        let before = self.slice(0, pos);
+        let after = self.slice(pos, self.native.len());
+        (before, after)
+    }
+
+    pub fn strip_prefix(&self, prefix: &OsStr) -> Option<Cow<'a, OsStr>> {
+        let n_prefix = to_native_int_representation(prefix);
+        let result = self.match_cow(
+            |b| b.strip_prefix(&*n_prefix).ok_or(()),
+            |o| o.strip_prefix(&*n_prefix).map(|x| x.to_vec()).ok_or(()),
+        );
+        result.ok()
+    }
+
+    pub fn strip_prefix_native(&self, prefix: &OsStr) -> Option<Cow<'a, NativeIntStr>> {
+        let n_prefix = to_native_int_representation(prefix);
+        let result = self.match_cow_native(
+            |b| b.strip_prefix(&*n_prefix).ok_or(()),
+            |o| o.strip_prefix(&*n_prefix).map(|x| x.to_vec()).ok_or(()),
+        );
+        result.ok()
+    }
+
+    fn match_cow<FnBorrow, FnOwned, Err>(
+        &self,
+        f_borrow: FnBorrow,
+        f_owned: FnOwned,
+    ) -> Result<Cow<'a, OsStr>, Err>
+    where
+        FnBorrow: FnOnce(&'a [NativeCharInt]) -> Result<&'a [NativeCharInt], Err>,
+        FnOwned: FnOnce(&Vec<NativeCharInt>) -> Result<Vec<NativeCharInt>, Err>,
+    {
+        match &self.native {
+            Cow::Borrowed(b) => {
+                let slice = f_borrow(b);
+                let os_str = slice.map(|x| from_native_int_representation(Cow::Borrowed(x)));
+                os_str
+            }
+            Cow::Owned(o) => {
+                let slice = f_owned(o);
+                let os_str = slice.map(from_native_int_representation_owned);
+                os_str.map(Cow::Owned)
+            }
+        }
+    }
+
+    fn match_cow_native<FnBorrow, FnOwned, Err>(
+        &self,
+        f_borrow: FnBorrow,
+        f_owned: FnOwned,
+    ) -> Result<Cow<'a, NativeIntStr>, Err>
+    where
+        FnBorrow: FnOnce(&'a [NativeCharInt]) -> Result<&'a [NativeCharInt], Err>,
+        FnOwned: FnOnce(&Vec<NativeCharInt>) -> Result<Vec<NativeCharInt>, Err>,
+    {
+        match &self.native {
+            Cow::Borrowed(b) => {
+                let slice = f_borrow(b);
+                slice.map(Cow::Borrowed)
+            }
+            Cow::Owned(o) => {
+                let slice = f_owned(o);
+                slice.map(Cow::Owned)
+            }
+        }
+    }
+}

src/uu/env/src/parse_error.rs

@@ -0,0 +1,55 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use std::fmt;
+
+use crate::string_parser;
+
+/// An error returned when string arg splitting fails.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum ParseError {
+    MissingClosingQuote {
+        pos: usize,
+        c: char,
+    },
+    InvalidBackslashAtEndOfStringInMinusS {
+        pos: usize,
+        quoting: String,
+    },
+    BackslashCNotAllowedInDoubleQuotes {
+        pos: usize,
+    },
+    InvalidSequenceBackslashXInMinusS {
+        pos: usize,
+        c: char,
+    },
+    ParsingOfVariableNameFailed {
+        pos: usize,
+        msg: String,
+    },
+    InternalError {
+        pos: usize,
+        sub_err: string_parser::Error,
+    },
+    ReachedEnd,
+    ContinueWithDelimiter,
+}
+
+impl fmt::Display for ParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(format!("{:?}", self).as_str())
+    }
+}
+
+impl std::error::Error for ParseError {}
+
+impl From<string_parser::Error> for ParseError {
+    fn from(value: string_parser::Error) -> Self {
+        Self::InternalError {
+            pos: value.peek_position,
+            sub_err: value,
+        }
+    }
+}

src/uu/env/src/split_iterator.rs

@@ -0,0 +1,375 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+//
+// This file is based on work from Tomasz Miąsko who published it as "shell_words" crate,
+// licensed under the Apache License, Version 2.0 <LICENSE-APACHE>
+// or the MIT license <LICENSE-MIT>, at your option.
+//
+//! Process command line according to parsing rules of original GNU env.
+//! Even though it looks quite like a POSIX syntax, the original
+//! "shell_words" implementation had to be adapted significantly.
+//!
+//! Apart from the grammar differences, there is a new feature integrated: $VARIABLE expansion.
+//!
+//! [GNU env] <https://www.gnu.org/software/coreutils/manual/html_node/env-invocation.html#g_t_002dS_002f_002d_002dsplit_002dstring-syntax>
+// spell-checker:ignore (words) Tomasz Miąsko rntfv FFFD varname
+
+#![forbid(unsafe_code)]
+
+use std::borrow::Cow;
+
+use crate::native_int_str::from_native_int_representation;
+use crate::native_int_str::NativeCharInt;
+use crate::native_int_str::NativeIntStr;
+use crate::native_int_str::NativeIntString;
+use crate::parse_error::ParseError;
+use crate::string_expander::StringExpander;
+use crate::string_parser::StringParser;
+use crate::variable_parser::VariableParser;
+
+const BACKSLASH: char = '\\';
+const DOUBLE_QUOTES: char = '\"';
+const SINGLE_QUOTES: char = '\'';
+const NEW_LINE: char = '\n';
+const DOLLAR: char = '$';
+
+const REPLACEMENTS: [(char, char); 9] = [
+    ('r', '\r'),
+    ('n', '\n'),
+    ('t', '\t'),
+    ('f', '\x0C'),
+    ('v', '\x0B'),
+    ('_', ' '),
+    ('#', '#'),
+    ('$', '$'),
+    ('"', '"'),
+];
+
+const ASCII_WHITESPACE_CHARS: [char; 6] = [' ', '\t', '\r', '\n', '\x0B', '\x0C'];
+
+pub struct SplitIterator<'a> {
+    expander: StringExpander<'a>,
+    words: Vec<Vec<NativeCharInt>>,
+}
+
+impl<'a> SplitIterator<'a> {
+    pub fn new(s: &'a NativeIntStr) -> Self {
+        Self {
+            expander: StringExpander::new(s),
+            words: Vec::new(),
+        }
+    }
+
+    fn skip_one(&mut self) -> Result<(), ParseError> {
+        self.expander
+            .get_parser_mut()
+            .consume_one_ascii_or_all_non_ascii()?;
+        Ok(())
+    }
+
+    fn take_one(&mut self) -> Result<(), ParseError> {
+        Ok(self.expander.take_one()?)
+    }
+
+    fn get_current_char(&self) -> Option<char> {
+        self.expander.peek().ok()
+    }
+
+    fn push_char_to_word(&mut self, c: char) {
+        self.expander.put_one_char(c);
+    }
+
+    fn push_word_to_words(&mut self) {
+        let word = self.expander.take_collected_output();
+        self.words.push(word);
+    }
+
+    fn get_parser(&self) -> &StringParser<'a> {
+        self.expander.get_parser()
+    }
+
+    fn get_parser_mut(&mut self) -> &mut StringParser<'a> {
+        self.expander.get_parser_mut()
+    }
+
+    fn substitute_variable<'x>(&'x mut self) -> Result<(), ParseError> {
+        let mut var_parse = VariableParser::<'a, '_> {
+            parser: self.get_parser_mut(),
+        };
+
+        let (name, default) = var_parse.parse_variable()?;
+
+        let varname_os_str_cow = from_native_int_representation(Cow::Borrowed(name));
+        let value = std::env::var_os(varname_os_str_cow);
+        match (&value, default) {
+            (None, None) => {} // do nothing, just replace it with ""
+            (Some(value), _) => {
+                self.expander.put_string(value);
+            }
+            (None, Some(default)) => {
+                self.expander.put_native_string(default);
+            }
+        };
+
+        Ok(())
+    }
+
+    fn check_and_replace_ascii_escape_code(&mut self, c: char) -> Result<bool, ParseError> {
+        if let Some(replace) = REPLACEMENTS.iter().find(|&x| x.0 == c) {
+            self.skip_one()?;
+            self.push_char_to_word(replace.1);
+            return Ok(true);
+        }
+
+        Ok(false)
+    }
+
+    fn make_invalid_sequence_backslash_xin_minus_s(&self, c: char) -> ParseError {
+        ParseError::InvalidSequenceBackslashXInMinusS {
+            pos: self.expander.get_parser().get_peek_position(),
+            c,
+        }
+    }
+
+    fn state_root(&mut self) -> Result<(), ParseError> {
+        loop {
+            match self.state_delimiter() {
+                Err(ParseError::ContinueWithDelimiter) => {}
+                Err(ParseError::ReachedEnd) => return Ok(()),
+                result => return result,
+            }
+        }
+    }
+
+    fn state_delimiter(&mut self) -> Result<(), ParseError> {
+        loop {
+            match self.get_current_char() {
+                None => return Ok(()),
+                Some('#') => {
+                    self.skip_one()?;
+                    self.state_comment()?;
+                }
+                Some(BACKSLASH) => {
+                    self.skip_one()?;
+                    self.state_delimiter_backslash()?;
+                }
+                Some(c) if ASCII_WHITESPACE_CHARS.contains(&c) => {
+                    self.skip_one()?;
+                }
+                Some(_) => {
+                    // Don't consume char. Will be done in unquoted state.
+                    self.state_unquoted()?;
+                }
+            }
+        }
+    }
+
+    fn state_delimiter_backslash(&mut self) -> Result<(), ParseError> {
+        match self.get_current_char() {
+            None => Err(ParseError::InvalidBackslashAtEndOfStringInMinusS {
+                pos: self.get_parser().get_peek_position(),
+                quoting: "Delimiter".into(),
+            }),
+            Some('_') | Some(NEW_LINE) => {
+                self.skip_one()?;
+                Ok(())
+            }
+            Some(DOLLAR) | Some(BACKSLASH) | Some('#') | Some(SINGLE_QUOTES)
+            | Some(DOUBLE_QUOTES) => {
+                self.take_one()?;
+                self.state_unquoted()
+            }
+            Some('c') => Err(ParseError::ReachedEnd),
+            Some(c) if self.check_and_replace_ascii_escape_code(c)? => self.state_unquoted(),
+            Some(c) => Err(self.make_invalid_sequence_backslash_xin_minus_s(c)),
+        }
+    }
+
+    fn state_unquoted(&mut self) -> Result<(), ParseError> {
+        loop {
+            match self.get_current_char() {
+                None => {
+                    self.push_word_to_words();
+                    return Err(ParseError::ReachedEnd);
+                }
+                Some(DOLLAR) => {
+                    self.substitute_variable()?;
+                }
+                Some(SINGLE_QUOTES) => {
+                    self.skip_one()?;
+                    self.state_single_quoted()?;
+                }
+                Some(DOUBLE_QUOTES) => {
+                    self.skip_one()?;
+                    self.state_double_quoted()?;
+                }
+                Some(BACKSLASH) => {
+                    self.skip_one()?;
+                    self.state_unquoted_backslash()?;
+                }
+                Some(c) if ASCII_WHITESPACE_CHARS.contains(&c) => {
+                    self.push_word_to_words();
+                    self.skip_one()?;
+                    return Ok(());
+                }
+                Some(_) => {
+                    self.take_one()?;
+                }
+            }
+        }
+    }
+
+    fn state_unquoted_backslash(&mut self) -> Result<(), ParseError> {
+        match self.get_current_char() {
+            None => Err(ParseError::InvalidBackslashAtEndOfStringInMinusS {
+                pos: self.get_parser().get_peek_position(),
+                quoting: "Unquoted".into(),
+            }),
+            Some(NEW_LINE) => {
+                self.skip_one()?;
+                Ok(())
+            }
+            Some('_') => {
+                self.skip_one()?;
+                self.push_word_to_words();
+                Err(ParseError::ContinueWithDelimiter)
+            }
+            Some('c') => {
+                self.push_word_to_words();
+                Err(ParseError::ReachedEnd)
+            }
+            Some(DOLLAR) | Some(BACKSLASH) | Some(SINGLE_QUOTES) | Some(DOUBLE_QUOTES) => {
+                self.take_one()?;
+                Ok(())
+            }
+            Some(c) if self.check_and_replace_ascii_escape_code(c)? => Ok(()),
+            Some(c) => Err(self.make_invalid_sequence_backslash_xin_minus_s(c)),
+        }
+    }
+
+    fn state_single_quoted(&mut self) -> Result<(), ParseError> {
+        loop {
+            match self.get_current_char() {
+                None => {
+                    return Err(ParseError::MissingClosingQuote {
+                        pos: self.get_parser().get_peek_position(),
+                        c: '\'',
+                    })
+                }
+                Some(SINGLE_QUOTES) => {
+                    self.skip_one()?;
+                    return Ok(());
+                }
+                Some(BACKSLASH) => {
+                    self.skip_one()?;
+                    self.split_single_quoted_backslash()?;
+                }
+                Some(_) => {
+                    self.take_one()?;
+                }
+            }
+        }
+    }
+
+    fn split_single_quoted_backslash(&mut self) -> Result<(), ParseError> {
+        match self.get_current_char() {
+            None => Err(ParseError::MissingClosingQuote {
+                pos: self.get_parser().get_peek_position(),
+                c: '\'',
+            }),
+            Some(NEW_LINE) => {
+                self.skip_one()?;
+                Ok(())
+            }
+            Some(SINGLE_QUOTES) | Some(BACKSLASH) => {
+                self.take_one()?;
+                Ok(())
+            }
+            Some(c) if REPLACEMENTS.iter().any(|&x| x.0 == c) => {
+                // See GNU test-suite e11: In single quotes, \t remains as it is.
+                // Comparing with GNU behavior: \a is not accepted and issues an error.
+                // So apparently only known sequences are allowed, even though they are not expanded.... bug of GNU?
+                self.push_char_to_word(BACKSLASH);
+                self.take_one()?;
+                Ok(())
+            }
+            Some(c) => Err(self.make_invalid_sequence_backslash_xin_minus_s(c)),
+        }
+    }
+
+    fn state_double_quoted(&mut self) -> Result<(), ParseError> {
+        loop {
+            match self.get_current_char() {
+                None => {
+                    return Err(ParseError::MissingClosingQuote {
+                        pos: self.get_parser().get_peek_position(),
+                        c: '"',
+                    })
+                }
+                Some(DOLLAR) => {
+                    self.substitute_variable()?;
+                }
+                Some(DOUBLE_QUOTES) => {
+                    self.skip_one()?;
+                    return Ok(());
+                }
+                Some(BACKSLASH) => {
+                    self.skip_one()?;
+                    self.state_double_quoted_backslash()?;
+                }
+                Some(_) => {
+                    self.take_one()?;
+                }
+            }
+        }
+    }
+
+    fn state_double_quoted_backslash(&mut self) -> Result<(), ParseError> {
+        match self.get_current_char() {
+            None => Err(ParseError::MissingClosingQuote {
+                pos: self.get_parser().get_peek_position(),
+                c: '"',
+            }),
+            Some(NEW_LINE) => {
+                self.skip_one()?;
+                Ok(())
+            }
+            Some(DOUBLE_QUOTES) | Some(DOLLAR) | Some(BACKSLASH) => {
+                self.take_one()?;
+                Ok(())
+            }
+            Some('c') => Err(ParseError::BackslashCNotAllowedInDoubleQuotes {
+                pos: self.get_parser().get_peek_position(),
+            }),
+            Some(c) if self.check_and_replace_ascii_escape_code(c)? => Ok(()),
+            Some(c) => Err(self.make_invalid_sequence_backslash_xin_minus_s(c)),
+        }
+    }
+
+    fn state_comment(&mut self) -> Result<(), ParseError> {
+        loop {
+            match self.get_current_char() {
+                None => return Err(ParseError::ReachedEnd),
+                Some(NEW_LINE) => {
+                    self.skip_one()?;
+                    return Ok(());
+                }
+                Some(_) => {
+                    self.get_parser_mut().skip_until_char_or_end(NEW_LINE);
+                }
+            }
+        }
+    }
+
+    pub fn split(mut self) -> Result<Vec<NativeIntString>, ParseError> {
+        self.state_root()?;
+        Ok(self.words)
+    }
+}
+
+pub fn split(s: &NativeIntStr) -> Result<Vec<NativeIntString>, ParseError> {
+    let splitted_args = SplitIterator::new(s).split()?;
+    Ok(splitted_args)
+}

src/uu/env/src/string_expander.rs

@@ -0,0 +1,92 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use std::{
+    ffi::{OsStr, OsString},
+    mem,
+    ops::Deref,
+};
+
+use crate::{
+    native_int_str::{to_native_int_representation, NativeCharInt, NativeIntStr},
+    string_parser::{Chunk, Error, StringParser},
+};
+
+/// This class makes parsing and word collection more convenient.
+///
+/// It manages an "output" buffer that is automatically filled.
+/// It provides "skip_one" and "take_one" that focus on
+/// working with ASCII separators. Thus they will skip or take
+/// all consecutive non-ascii char sequences at once.
+pub struct StringExpander<'a> {
+    parser: StringParser<'a>,
+    output: Vec<NativeCharInt>,
+}
+
+impl<'a> StringExpander<'a> {
+    pub fn new(input: &'a NativeIntStr) -> Self {
+        Self {
+            parser: StringParser::new(input),
+            output: Vec::default(),
+        }
+    }
+
+    pub fn new_at(input: &'a NativeIntStr, pos: usize) -> Self {
+        Self {
+            parser: StringParser::new_at(input, pos),
+            output: Vec::default(),
+        }
+    }
+
+    pub fn get_parser(&self) -> &StringParser<'a> {
+        &self.parser
+    }
+
+    pub fn get_parser_mut(&mut self) -> &mut StringParser<'a> {
+        &mut self.parser
+    }
+
+    pub fn peek(&self) -> Result<char, Error> {
+        self.parser.peek()
+    }
+
+    pub fn skip_one(&mut self) -> Result<(), Error> {
+        self.get_parser_mut().consume_one_ascii_or_all_non_ascii()?;
+        Ok(())
+    }
+
+    pub fn get_peek_position(&self) -> usize {
+        self.get_parser().get_peek_position()
+    }
+
+    pub fn take_one(&mut self) -> Result<(), Error> {
+        let chunks = self.parser.consume_one_ascii_or_all_non_ascii()?;
+        for chunk in chunks {
+            match chunk {
+                Chunk::InvalidEncoding(invalid) => self.output.extend(invalid),
+                Chunk::ValidSingleIntChar((_c, ni)) => self.output.push(ni),
+            }
+        }
+        Ok(())
+    }
+
+    pub fn put_one_char(&mut self, c: char) {
+        let os_str = OsString::from(c.to_string());
+        self.put_string(os_str);
+    }
+
+    pub fn put_string<S: AsRef<OsStr>>(&mut self, os_str: S) {
+        let native = to_native_int_representation(os_str.as_ref());
+        self.output.extend(native.deref());
+    }
+
+    pub fn put_native_string(&mut self, n_str: &NativeIntStr) {
+        self.output.extend(n_str);
+    }
+
+    pub fn take_collected_output(&mut self) -> Vec<NativeCharInt> {
+        mem::take(&mut self.output)
+    }
+}

src/uu/env/src/string_parser.rs

@@ -0,0 +1,182 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+//
+// spell-checker:ignore (words) splitted FFFD
+#![forbid(unsafe_code)]
+
+use std::{borrow::Cow, ffi::OsStr};
+
+use crate::native_int_str::{
+    from_native_int_representation, get_char_from_native_int, get_single_native_int_value,
+    NativeCharInt, NativeIntStr,
+};
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Error {
+    pub peek_position: usize,
+    pub err_type: ErrorType,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum ErrorType {
+    EndOfInput,
+    InternalError,
+}
+
+/// Provides a valid char or a invalid sequence of bytes.
+///
+/// Invalid byte sequences can't be splitted in any meaningful way.
+/// Thus, they need to be consumed as one piece.
+pub enum Chunk<'a> {
+    InvalidEncoding(&'a NativeIntStr),
+    ValidSingleIntChar((char, NativeCharInt)),
+}
+
+/// This class makes parsing a OsString char by char more convenient.
+///
+/// It also allows to capturing of intermediate positions for later splitting.
+pub struct StringParser<'a> {
+    input: &'a NativeIntStr,
+    pointer: usize,
+    remaining: &'a NativeIntStr,
+}
+
+impl<'a> StringParser<'a> {
+    pub fn new(input: &'a NativeIntStr) -> Self {
+        let mut instance = Self {
+            input,
+            pointer: 0,
+            remaining: input,
+        };
+        instance.set_pointer(0);
+        instance
+    }
+
+    pub fn new_at(input: &'a NativeIntStr, pos: usize) -> Self {
+        let mut instance = Self::new(input);
+        instance.set_pointer(pos);
+        instance
+    }
+
+    pub fn get_input(&self) -> &'a NativeIntStr {
+        self.input
+    }
+
+    pub fn get_peek_position(&self) -> usize {
+        self.pointer
+    }
+
+    pub fn peek(&self) -> Result<char, Error> {
+        self.peek_char_at_pointer(self.pointer)
+    }
+
+    fn make_err(&self, err_type: ErrorType) -> Error {
+        Error {
+            peek_position: self.get_peek_position(),
+            err_type,
+        }
+    }
+
+    pub fn peek_char_at_pointer(&self, at_pointer: usize) -> Result<char, Error> {
+        let split = self.input.split_at(at_pointer).1;
+        if split.is_empty() {
+            return Err(self.make_err(ErrorType::EndOfInput));
+        }
+        if let Some((c, _ni)) = get_char_from_native_int(split[0]) {
+            Ok(c)
+        } else {
+            Ok('\u{FFFD}')
+        }
+    }
+
+    fn get_chunk_with_length_at(&self, pointer: usize) -> Result<(Chunk<'a>, usize), Error> {
+        let (_before, after) = self.input.split_at(pointer);
+        if after.is_empty() {
+            return Err(self.make_err(ErrorType::EndOfInput));
+        }
+
+        if let Some(c_ni) = get_char_from_native_int(after[0]) {
+            Ok((Chunk::ValidSingleIntChar(c_ni), 1))
+        } else {
+            let mut i = 1;
+            while i < after.len() {
+                if let Some(_c) = get_char_from_native_int(after[i]) {
+                    break;
+                }
+                i += 1;
+            }
+
+            let chunk = &after[0..i];
+            Ok((Chunk::InvalidEncoding(chunk), chunk.len()))
+        }
+    }
+
+    pub fn peek_chunk(&self) -> Option<Chunk<'a>> {
+        return self
+            .get_chunk_with_length_at(self.pointer)
+            .ok()
+            .map(|(chunk, _)| chunk);
+    }
+
+    pub fn consume_chunk(&mut self) -> Result<Chunk<'a>, Error> {
+        let (chunk, len) = self.get_chunk_with_length_at(self.pointer)?;
+        self.set_pointer(self.pointer + len);
+        Ok(chunk)
+    }
+
+    pub fn consume_one_ascii_or_all_non_ascii(&mut self) -> Result<Vec<Chunk<'a>>, Error> {
+        let mut result = Vec::<Chunk<'a>>::new();
+        loop {
+            let data = self.consume_chunk()?;
+            let was_ascii = if let Chunk::ValidSingleIntChar((c, _ni)) = &data {
+                c.is_ascii()
+            } else {
+                false
+            };
+            result.push(data);
+            if was_ascii {
+                return Ok(result);
+            }
+
+            match self.peek_chunk() {
+                Some(Chunk::ValidSingleIntChar((c, _ni))) if c.is_ascii() => return Ok(result),
+                None => return Ok(result),
+                _ => {}
+            }
+        }
+    }
+
+    pub fn skip_multiple(&mut self, skip_byte_count: usize) {
+        let end_ptr = self.pointer + skip_byte_count;
+        self.set_pointer(end_ptr);
+    }
+
+    pub fn skip_until_char_or_end(&mut self, c: char) {
+        let native_rep = get_single_native_int_value(&c).unwrap();
+        let pos = self.remaining.iter().position(|x| *x == native_rep);
+
+        if let Some(pos) = pos {
+            self.set_pointer(self.pointer + pos);
+        } else {
+            self.set_pointer(self.input.len());
+        }
+    }
+
+    pub fn substring(&self, range: &std::ops::Range<usize>) -> &'a NativeIntStr {
+        let (_before1, after1) = self.input.split_at(range.start);
+        let (middle, _after2) = after1.split_at(range.end - range.start);
+        middle
+    }
+
+    pub fn peek_remaining(&self) -> Cow<'a, OsStr> {
+        from_native_int_representation(Cow::Borrowed(self.remaining))
+    }
+
+    pub fn set_pointer(&mut self, new_pointer: usize) {
+        self.pointer = new_pointer;
+        let (_before, after) = self.input.split_at(self.pointer);
+        self.remaining = after;
+    }
+}

src/uu/env/src/variable_parser.rs

@@ -0,0 +1,158 @@
+// This file is part of the uutils coreutils package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+
+use std::ops::Range;
+
+use crate::{native_int_str::NativeIntStr, parse_error::ParseError, string_parser::StringParser};
+
+pub struct VariableParser<'a, 'b> {
+    pub parser: &'b mut StringParser<'a>,
+}
+
+impl<'a, 'b> VariableParser<'a, 'b> {
+    fn get_current_char(&self) -> Option<char> {
+        self.parser.peek().ok()
+    }
+
+    fn check_variable_name_start(&self) -> Result<(), ParseError> {
+        if let Some(c) = self.get_current_char() {
+            if c.is_ascii_digit() {
+                return Err(ParseError::ParsingOfVariableNameFailed {
+                    pos: self.parser.get_peek_position(),
+                    msg: format!("Unexpected character: '{}', expected variable name must not start with 0..9", c) });
+            }
+        }
+        Ok(())
+    }
+
+    fn skip_one(&mut self) -> Result<(), ParseError> {
+        self.parser.consume_chunk()?;
+        Ok(())
+    }
+
+    fn parse_braced_variable_name(
+        &mut self,
+    ) -> Result<(&'a NativeIntStr, Option<&'a NativeIntStr>), ParseError> {
+        let pos_start = self.parser.get_peek_position();
+
+        self.check_variable_name_start()?;
+
+        let (varname_end, default_end);
+        loop {
+            match self.get_current_char() {
+                None => {
+                    return Err(ParseError::ParsingOfVariableNameFailed {
+                        pos: self.parser.get_peek_position(), msg: "Missing closing brace".into() })
+                },
+                Some(c) if !c.is_ascii() || c.is_ascii_alphanumeric() || c == '_' => {
+                    self.skip_one()?;
+                }
+                Some(':') => {
+                    varname_end = self.parser.get_peek_position();
+                    loop {
+                        match self.get_current_char() {
+                            None => {
+                                return Err(ParseError::ParsingOfVariableNameFailed {
+                                    pos: self.parser.get_peek_position(),
+                                    msg: "Missing closing brace after default value".into() })
+                            },
+                            Some('}') => {
+                                default_end = Some(self.parser.get_peek_position());
+                                self.skip_one()?;
+                                break
+                            },
+                            Some(_) => {
+                                self.skip_one()?;
+                            },
+                        }
+                    }
+                    break;
+                },
+                Some('}') => {
+                    varname_end = self.parser.get_peek_position();
+                    default_end = None;
+                    self.skip_one()?;
+                    break;
+                },
+                Some(c) => {
+                    return Err(ParseError::ParsingOfVariableNameFailed {
+                        pos: self.parser.get_peek_position(),
+                        msg: format!("Unexpected character: '{}', expected a closing brace ('}}') or colon (':')", c)
+                    })
+                },
+            };
+        }
+
+        let default_opt = if let Some(default_end) = default_end {
+            Some(self.parser.substring(&Range {
+                start: varname_end + 1,
+                end: default_end,
+            }))
+        } else {
+            None
+        };
+
+        let varname = self.parser.substring(&Range {
+            start: pos_start,
+            end: varname_end,
+        });
+
+        Ok((varname, default_opt))
+    }
+
+    fn parse_unbraced_variable_name(&mut self) -> Result<&'a NativeIntStr, ParseError> {
+        let pos_start = self.parser.get_peek_position();
+
+        self.check_variable_name_start()?;
+
+        loop {
+            match self.get_current_char() {
+                None => break,
+                Some(c) if c.is_ascii_alphanumeric() || c == '_' => {
+                    self.skip_one()?;
+                }
+                Some(_) => break,
+            };
+        }
+
+        let pos_end = self.parser.get_peek_position();
+
+        if pos_end == pos_start {
+            return Err(ParseError::ParsingOfVariableNameFailed {
+                pos: pos_start,
+                msg: "Missing variable name".into(),
+            });
+        }
+
+        let varname = self.parser.substring(&Range {
+            start: pos_start,
+            end: pos_end,
+        });
+
+        Ok(varname)
+    }
+
+    pub fn parse_variable(
+        &mut self,
+    ) -> Result<(&'a NativeIntStr, Option<&'a NativeIntStr>), ParseError> {
+        self.skip_one()?;
+
+        let (name, default) = match self.get_current_char() {
+            None => {
+                return Err(ParseError::ParsingOfVariableNameFailed {
+                    pos: self.parser.get_peek_position(),
+                    msg: "missing variable name".into(),
+                })
+            }
+            Some('{') => {
+                self.skip_one()?;
+                self.parse_braced_variable_name()?
+            }
+            Some(_) => (self.parse_unbraced_variable_name()?, None),
+        };
+
+        Ok((name, default))
+    }
+}

tests/common/util.rs

@@ -15,7 +15,6 @@ use pretty_assertions::assert_eq;
 use rlimit::setrlimit;
 #[cfg(feature = "sleep")]
 use rstest::rstest;
-#[cfg(unix)]
 use std::borrow::Cow;
 use std::collections::VecDeque;
 #[cfg(not(windows))]
@@ -352,6 +351,11 @@ impl CmdResult {
         std::str::from_utf8(&self.stderr).unwrap()
     }
 
+    /// Returns the program's standard error as a string slice, automatically handling invalid utf8
+    pub fn stderr_str_lossy(&self) -> Cow<'_, str> {
+        String::from_utf8_lossy(&self.stderr)
+    }
+
     /// Returns the program's standard error as a string
     /// consumes self
     pub fn stderr_move_str(self) -> String {
@@ -372,6 +376,14 @@ impl CmdResult {
 
     #[track_caller]
     pub fn code_is(&self, expected_code: i32) -> &Self {
+        let fails = self.code() != expected_code;
+        if fails {
+            eprintln!(
+                "stdout:\n{}\nstderr:\n{}",
+                self.stdout_str(),
+                self.stderr_str()
+            );
+        }
         assert_eq!(self.code(), expected_code);
         self
     }
@@ -395,10 +407,8 @@ impl CmdResult {
     pub fn success(&self) -> &Self {
         assert!(
             self.succeeded(),
-            "Command was expected to succeed. Exit code: {}.\nstdout = {}\n stderr = {}",
-            self.exit_status()
-                .code()
-                .map_or("n/a".to_string(), |code| code.to_string()),
+            "Command was expected to succeed. code: {}\nstdout = {}\n stderr = {}",
+            self.code(),
             self.stdout_str(),
             self.stderr_str()
         );
@@ -2674,7 +2684,7 @@ pub fn expected_result(ts: &TestScenario, args: &[&str]) -> std::result::Result<
     let (stdout, stderr): (String, String) = if cfg!(target_os = "linux") {
         (
             result.stdout_str().to_string(),
-            result.stderr_str().to_string(),
+            result.stderr_str_lossy().to_string(),
         )
     } else {
         // `host_name_for` added prefix, strip 'g' prefix from results:
@@ -2682,7 +2692,7 @@ pub fn expected_result(ts: &TestScenario, args: &[&str]) -> std::result::Result<
         let to = &from[1..];
         (
             result.stdout_str().replace(&from, to),
-            result.stderr_str().replace(&from, to),
+            result.stderr_str_lossy().replace(&from, to),
         )
     };
 

tests/fixtures/env/runBat.bat

@@ -0,0 +1 @@
+echo Hello Windows World!

util/build-gnu.sh

@@ -221,6 +221,8 @@ grep -rlE '/usr/local/bin/\s?/usr/local/bin' init.cfg tests/* | xargs -r sed -Ei
 # we should not regress our project just to match what GNU is going.
 # So, do some changes on the fly
 
+patch -N -r - -d "$path_GNU" -p 1 -i "`realpath \"$path_UUTILS/util/gnu-patches/tests_env_env-S.pl.patch\"`" || true
+
 sed -i -e "s|rm: cannot remove 'e/slink'|rm: cannot remove 'e'|g" tests/rm/fail-eacces.sh
 
 sed -i -e "s|rm: cannot remove 'a/b'|rm: cannot remove 'a'|g" tests/rm/fail-2eperm.sh

util/gnu-patches/tests_env_env-S.pl.patch

@@ -0,0 +1,47 @@
+diff --git a/tests/env/env-S.pl b/tests/env/env-S.pl
+index 710ca82cf..af7cf6efa 100755
+--- a/tests/env/env-S.pl
++++ b/tests/env/env-S.pl
+@@ -209,27 +209,28 @@ my @Tests =
+       {ERR=>"$prog: no terminating quote in -S string\n"}],
+      ['err5', q[-S'A=B\\q'], {EXIT=>125},
+       {ERR=>"$prog: invalid sequence '\\q' in -S\n"}],
+-     ['err6', q[-S'A=$B'], {EXIT=>125},
+-      {ERR=>"$prog: only \${VARNAME} expansion is supported, error at: \$B\n"}],
++     ['err6', q[-S'A=$B echo hello'], {EXIT=>0},
++      {OUT=>"hello"}],
+      ['err7', q[-S'A=${B'], {EXIT=>125},
+-      {ERR=>"$prog: only \${VARNAME} expansion is supported, " .
+-           "error at: \${B\n"}],
++      {ERR=>"$prog" . qq[: variable name issue (at 5): Missing closing brace\n]}],
+      ['err8', q[-S'A=${B%B}'], {EXIT=>125},
+-      {ERR=>"$prog: only \${VARNAME} expansion is supported, " .
+-           "error at: \${B%B}\n"}],
++      {ERR=>"$prog" . qq[: variable name issue (at 5): Unexpected character: '%', expected a closing brace ('}') or colon (':')\n]}],
+      ['err9', q[-S'A=${9B}'], {EXIT=>125},
+-      {ERR=>"$prog: only \${VARNAME} expansion is supported, " .
+-           "error at: \${9B}\n"}],
++      {ERR=>"$prog" . qq[: variable name issue (at 4): Unexpected character: '9', expected variable name must not start with 0..9\n]}],
+ 
+      # Test incorrect shebang usage (extraneous whitespace).
+      ['err_sp2', q['-v -S cat -n'], {EXIT=>125},
+-      {ERR=>"env: invalid option -- ' '\n" .
+-            "env: use -[v]S to pass options in shebang lines\n" .
+-           "Try 'env --help' for more information.\n"}],
++      {ERR=>"$prog: error: unexpected argument '- ' found\n\n" .
++            "  tip: to pass '- ' as a value, use '-- - '\n\n" .
++            "Usage: $prog [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n\n" .
++            "For more information, try '--help'.\n" .
++            "$prog: use -[v]S to pass options in shebang lines\n"}],
+      ['err_sp3', q['-v	-S cat -n'], {EXIT=>125}, # embedded tab after -v
+-      {ERR=>"env: invalid option -- '\t'\n" .
+-            "env: use -[v]S to pass options in shebang lines\n" .
+-           "Try 'env --help' for more information.\n"}],
++      {ERR=>"$prog: error: unexpected argument '-\t' found\n\n" .
++            "  tip: to pass '-\t' as a value, use '-- -\t'\n\n" .
++            "Usage: $prog [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]\n\n" .
++            "For more information, try '--help'.\n" .
++            "$prog: use -[v]S to pass options in shebang lines\n"}],
+ 
+      # Also diagnose incorrect shebang usage when failing to exec.
+      # This typically happens with: