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
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
boost::process::v2::process_stdio — The initializer for the stdio of a subprocess.
// In header: <boost/process/v2/stdio.hpp> struct process_stdio { // public member functions error_code on_exec_setup(posix::default_launcher &, const filesystem::path &, const char *const *); // public data members unspecified in; unspecified out; unspecified err; };
The subprocess initializer has three members:
in for stdin
out for stdout
err for stderr
If the initializer is present all three will be set for the subprocess. By default they will inherit the stdio handles from the parent process. This means that this will forward stdio to the subprocess:
asio::io_context ctx; v2::process proc(ctx, "/bin/bash", {}, v2::process_stdio{});
No constructors are provided in order to support designated initializers in later version of C++.
asio::io_context ctx; v2::process proc17(ctx, "/bin/bash", {}, v2::process_stdio{.stderr=nullptr}); v2::process proc17(ctx, "/bin/bash", {}, v2::process_stdio{ {}, {}, nullptr}); stdin ^ ^ stderr
Valid initializers for any stdio are:
std::nullptr_t assigning a null-device
FILE* any open file, including stdin, stdout and stderr
a filesystem::path, which will open a readable or writable depending on the direction of the stream
native_handle any native file handle (HANDLE on windows) or file descriptor (int on posix)
any io-object with a .native_handle() function that is compatible with the above. E.g. a asio::ip::tcp::socket
an asio::basic_writeable_pipe for stdin or asio::basic_readable_pipe for stderr/stdout.