Godot: OS.execute trouble with shell evaluation ("export PATH=test && echo $PATH" doesn't work)

[QiuleiWang]

Godot version:
3.2.1

OS/device including version:
macos

Issue description:
OS.execute("/bin/bash", ['-c',"export PATH=test && echo $PATH"], true, output,true)
print(output)
print result
[/usr/bin:/bin:/usr/sbin:/sbin
]
don't work

Steps to reproduce:

Minimal reproduction project:

[akien-mga]

It also doesn't work in Bash...

$ /bin/bash -c "export PATH=test && echo $PATH"
/home/akien/Projects/godot/emscripten/emsdk:/home/akien/Projects/godot/emscripten/emsdk/upstream/emscripten:/home/akien/Projects/godot/emscripten/emsdk/node/12.9.1_64bit/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/usr/lib64/qt5/bin:/usr/lib64/qt4/bin:/home/akien/.cargo/bin:/home/akien/.local/bin:/home/akien/bin:/home/akien/.cargo/bin

[akien-mga]

Actually it works when using single quotes to prevent shell expansion:

$ /bin/bash -c 'export PATH=test; echo $PATH'
test

[akien-mga]

The problem is that we use double quotes to enclose arguments passed to the executable (here /bin/bash), which means that shell variables get expanded. That's likely what most users would expect, but in this case it makes things tricky.

https://github.com/godotengine/godot/blob/5fede4a81c67961c6fb2309b9b0ceb753d143566/drivers/unix/os_unix.cpp#L283-L296

You can work it around by closing the double-quoted string and concatenating with a single-quote enclosed string:

OS.execute("/bin/bash", ['-c', "\"'export PATH=test && echo $PATH'\""], true, output, true)

I'm not sure what we can do to improve this. One solution would be to switch to using single quotes by default (no shell expansion), and then add a boolean parameter to toggle shell expansion (thus using double quotes as delimiter instead of single quotes).

[QiuleiWang]

/bin/bash -c 'export PATH=test; echo $PATH'
gdscript don't work
OS.execute("/bin/bash", ['-c','export PATH=test && echo $PATH'], true, output,true)

[/usr/bin:/bin:/usr/sbin:/sbin
]

[QiuleiWang]

The problem is that we use double quotes to enclose arguments passed to the executable (here /bin/bash), which means that shell variables get expanded. That's likely what most users would expect, but in this case it makes things tricky.

https://github.com/godotengine/godot/blob/5fede4a81c67961c6fb2309b9b0ceb753d143566/drivers/unix/os_unix.cpp#L283-L296

You can work it around by closing the double-quoted string and concatenating with a single-quote enclosed string:

OS.execute("/bin/bash", ['-c', "\"'export PATH=test && echo $PATH'\""], true, output, true)

I'm not sure what we can do to improve this. One solution would be to switch to using single quotes by default (no shell expansion), and then add a boolean parameter to toggle shell expansion (thus using double quotes as delimiter instead of single quotes).

OS.execute("/bin/bash", ['-c', "\"'export PATH=test && echo $PATH'\""], true, output, true)
That's right.

[akien-mga]

I'll keep it open for now as we might want to change the method, or at least improve the documentation to mention this caveat.

[blinry]

So @bleeptrack and I just stumbled over this problem – we definitely had expected that OS.execute would pass the arguments to the command literally, without any modification. A more stable implementation (using C's execv?) would sure be nice!

@akien-mga, your workaround was helpful and worked, thanks! To preserve single quotes inside the command, we ended up replacing all of them by '"'"', like this:

var command = "echo \"hello 'world'\""
command = '"\''+command.replace("'", "'\"'\"'")+'\'"'
OS.execute("/bin/bash, ["-c",  command])