On Mon, 30 Oct 2023 15:36:50 -0500 Yihui Xie <x...@yihui.name> wrote:
> I have read about "system() not using a shell on Windows" on the help > page many times before but never understood what it means technically. This means resolving the path to the executable, then calling CreateProcess() to launch that executable with the given parameters and other settings: https://github.com/wch/r-source/blob/635a672151a18a0e475986af592fab59e7479a9b/src/gnuwin32/run.c#L378-L386 https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessa As far as I know, CreateProcess() is the most direct officially supported way to launch a process on Windows. The alternative would be assembling the command line and giving it to cmd.exe to interpret and launch, as done by shell(). This can be more convenient in certain cases, as the shell can expand environment variables from %STRINGS% or launch multiple commands separated by &, but it also requires extreme care: quoting rules are subtle and have to be understood on both the cmd.exe level *and* the C runtime level (on Windows, the C runtime is responsible for parsing the string returned from GetCommandLine() and creating the `argv` command line argument array from it). Working with shell command lines is like using string operations on deparse() output instead of directly operating on language objects: less complicated than rocket surgery, but better avoided if alternatives exist. -- Best regards, Ivan ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
