Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for a snapshot of the develop branch, built from commit b8adfe0e57.

Struct shell

boost::process::v2::shell — Utility to parse commands.

Synopsis

// In header: <boost/process/v2/shell.hpp>


struct shell {
  // types
  typedef char          char_type;
  typedef const char ** args_type;

  // construct/copy/destruct
  shell() = default;
  template<typename Char, typename Traits> 
    shell(basic_string_view< Char, Traits >);
  shell(basic_cstring_ref< char_type >);
  shell(basic_string_view< typename std::conditional< std::is_same< char_type, char >::value, wchar_t, char >::type >);
  shell(const shell &) = delete;
  shell(shell &&) noexcept;
  shell & operator=(const shell &) = delete;
  shell & operator=(shell &&) noexcept;
  ~shell();

  // public member functions
  int argc() const;
  char_type ** argv() const;
  char_type ** begin() const;
  char_type ** end() const;
  bool empty() const;
  std::size_t size() const;
  args_type args() const;
  template<typename Environment = environment::current_view> 
    filesystem::path exe(Environment && = environment::current()) const;

  // private member functions
  void parse_();
};

Description

This utility class parses command lines into tokens and allows users to executed based on textual inputs.

In v1, this was possible directly when starting a process, but has been removed based on the security risks associated with this.

By making the shell parsing explicitly, it encourages a user to run a sanity check on the executable before launching it.

Example.

asio::io_context ctx;

auto cmd = shell("my-app --help");
auto exe = cmd.exe();
check_if_malicious(exe);

process proc{ctx, exe, cmd.args()};

`shell` public construct/copy/destruct

```
shell() = default;
```

template<typename Char, typename Traits> 
  shell(basic_string_view< Char, Traits > input);

shell(basic_cstring_ref< char_type > input);

shell(basic_string_view< typename std::conditional< std::is_same< char_type, char >::value, wchar_t, char >::type > input);

```
shell(const shell &) = delete;
```
```
shell(shell && lhs) noexcept;
```

shell & operator=(const shell &) = delete;

shell & operator=(shell && lhs) noexcept;

```
~shell();
```

`shell` public member functions

```
int argc() const;
```
```
char_type ** argv() const;
```
```
char_type ** begin() const;
```
```
char_type ** end() const;
```
```
bool empty() const;
```
```
std::size_t size() const;
```
```
args_type args() const;
```
Native representation of the arguments to be used - excluding the executable.

template<typename Environment = environment::current_view> 
  filesystem::path exe(Environment && env = environment::current()) const;

`shell` private member functions

```
void parse_();
```