create-process-rust is a command line utility for Microsoft Windows to explore the strange behaviour of command lines on Windows compared to UNIX.
On Windows, if a process asks the operating system for it's command line, it doesn't get an array of arguments, but only one UTF-16 string.
The parsing into individual arguments is normally done with this algorithm: https://learn.microsoft.com/en-us/cpp/c-language/parsing-c-command-line-arguments?view=msvc-170 .
This is the algorithm of the Microsoft C-Runtime. (It can also be implemented in other languages.)
But many programs including cmd.exe and msbuild.exe do it differently.
When working in a shell or command prompt, one has to think about the how the shell processes the input of the user and how it construct the command line, that it passes to CreateProcessW().
CreateProcessW() is the low level function to create processes on Windows.
For example the projects “git for Windows”, MSYS2 and Cygwin port the shell Bash to windows. This ported bash works like this (simplified):
- The user enters a command line
- The command line is split into an array of arguments, respecting the special characters of bash, for example:
',",$, ... - UNIX paths are converted to Windows paths (forward slash to backslash)
- A new command line is put together acording to the Microsoft CRT algorithm.
CreateProcessW()is called with that command line.
By the way: PowerShell has very crazy rules how the final command line is created, and they are different between versions. See for example:
- PSNativeCommandArgumentPassing
- Issue on GitHub: PowerShell/PowerShell#14747
On Linux, if a process asks the operating system for it's command line, it gets an array of arguments directly from the OS. These arguments do not have an encoding, but cannot contain a null byte. The encoding used to decode these arguments is typlically UTF-8. But some programs look into environment variables to figure out, which arguments to use. I assume, that those programs asume, that the environments variables (their names and their values) are encoded in ASCII.
Use --help to get the up-to-date usage description:
create-process-rust.exe --help
Here is an example. If we enter this commandline in git-bash:
target/debug/create-process-rust.exe --print-args-only 'Alice asks: "How are you?"' 'Bob answers: "I'\''m fine!"' --some-path /c/Program\ Files/GitWe get for example this output:
The command line was converted losslessly.
The command line is put in quotes (»«). If those quotes are inside the command line, they are not escaped. The command line is:
»C:\Users\j0le\prog\create-process-rust\target\debug\create-process-rust.exe --print-args-only "Alice asks: \"How are you?\"" "Bob answers: \"I'm fine!\"" --some-path "C:/Program Files/Git"«
Argument 0, 0 .. 75, lossless: »C:\Users\j0le\prog\create-process-rust\target\debug\create-process-rust.exe«, raw: »C:\Users\j0le\prog\create-process-rust\target\debug\create-process-rust.exe«
Argument 1, 76 .. 93, lossless: »--print-args-only«, raw: »--print-args-only«
Argument 2, 94 .. 124, lossless: »Alice asks: "How are you?"«, raw: »"Alice asks: \"How are you?\""«
Argument 3, 125 .. 153, lossless: »Bob answers: "I'm fine!"«, raw: »"Bob answers: \"I'm fine!\""«
Argument 4, 154 .. 165, lossless: »--some-path«, raw: »--some-path«
Argument 5, 166 .. 188, lossless: »C:/Program Files/Git«, raw: »"C:/Program Files/Git"«
If we enter the following into cmd.exe:
target\debug\create-process-rust.exe --print-args-only "Alice asks: \"How are you?\"" "Bob answers: \"I'm fine!\"" --some-path "C:/Program Files/Git"
We get:
The command line was converted losslessly.
The command line is put in quotes (»«). If those quotes are inside the command line, they are not escaped. The command line is:
»target\debug\create-process-rust.exe --print-args-only "Alice asks: \"How are you?\"" "Bob answers: \"I'm fine!\"" --some-path "C:/Program Files/Git"«
Argument 0, 0 .. 36, lossless: »target\debug\create-process-rust.exe«, raw: »target\debug\create-process-rust.exe«
Argument 1, 38 .. 55, lossless: »--print-args-only«, raw: »--print-args-only«
Argument 2, 56 .. 86, lossless: »Alice asks: "How are you?"«, raw: »"Alice asks: \"How are you?\""«
Argument 3, 92 .. 120, lossless: »Bob answers: "I'm fine!"«, raw: »"Bob answers: \"I'm fine!\""«
Argument 4, 121 .. 132, lossless: »--some-path«, raw: »--some-path«
Argument 5, 133 .. 155, lossless: »C:/Program Files/Git«, raw: »"C:/Program Files/Git"«
As you can see, cmd.exe preserves spaces between arguments, and git-bash does not. But somehow an extra spaces apears after argument zero.
Set the environement variable MSYS_NO_PATHCONV to 1 to disable path conversion; for example:
MSYS_NO_PATHCONV=1 ./create-process-rust.exe --program "$(cygpath -wa "$(which cmd.exe)" )" --cmd-line-in-arg '/c (echo hello world)'Install git, by taking one of these links:
Install the rust toolchain with rustup by following these instructions: https://www.rust-lang.org/tools/install
Clone this repository:
cd some/nice/directory
git clone https://github.com/j0le/create-process-rust.git
Replace some/nice/directory with the path to some nice directory.
Change your current working directory to the directory, where the repository is:
cd create-process-rust
If you use cmd.exe as your shell, execute this:
"%USERPROFILE%\.cargo\bin\cargo.exe" build
If you use git-bash, execute this:
~/.cargo/bin/cargo build
To execute the program, use this command.
cargo run -- --help
Replace cargo with the path to the cargo executable.
by me:
- https://github.com/j0le/process-starter
- https://github.com/j0le/get-command-line
- https://github.com/j0le/cpwd – cpwd – Copy the path of the current working directory/folder to the clipboard
by others:
- https://github.com/mklement0/Native
- https://github.com/gerardog/gsudo
- https://github.com/yozhgoor/CreateProcessW (didn’t tested that yet)
- https://github.com/clap-rs/clap
For lincense information see the file LICENSE.txt.