Go: os/exec: Cannot execute command with space in the name on Windows, when there are parameters

[calmh]

Go 1.7.1 on windows-amd64, Windows 10 latest.

Consider a test project:

src/github.com/calmh/wincmdtest/
    main.go
    folder name/
        test.bat

main.go contents:

package main

import (
    "fmt"
    "os/exec"
    "strings"
)

func main() {
    execCmd("./folder name/test.bat")
    execCmd("./folder name/test.bat", "one param")
}

func execCmd(path string, args ...string) {
    fmt.Printf("Running: %q %q\n", path, strings.Join(args, " "))
    cmd := exec.Command(path, args...)
    bs, err := cmd.CombinedOutput()
    fmt.Printf("Output: %s", bs)
    fmt.Printf("Error: %v\n\n", err)
}

folder name/test.bat contents:

@echo off
echo Success

Expected output is two runs with "Success" in them.

Actual:

C:\Users\jb\Go\src\github.com\calmh\wincmdtest>go run main.go
Running: "./folder name/test.bat" ""
Output: Success
Error: <nil>

Running: "./folder name/test.bat" "one param"
Output: '.' is not recognized as an internal or external command,
operable program or batch file.
Error: exit status 1

It appears that having params on a command, where the command contains a space, breaks the parsing of it. I haven't been able to work around this by experimenting with various ways of quoting the command, using backslashes or slashes, etc.

[calmh]

I started following this down through syscall.StartProcess, but not really being a Windows programmer I ran into unacceptable levels of nope almost immediately so probably won't try to fix this myself, sorry. :(

[alexbrainman]

It appears that having params on a command, where the command contains a space, breaks the parsing of it.

Go encodes child process parameters in a way that is understood by most programs. Go uses rules similar to what CommandLineToArgvW implements.

Unfortunately, your child process is cmd.exe (cmd.exe is called to execute the batch file you've requested). And cmd.exe parses its input parameters differently.

You can read this very long post http://daviddeley.com/autohotkey/parameters/parameters.htm#WIN about it all.

I haven't been able to work around this by experimenting with various ways of quoting the command, using backslashes or slashes, etc.

You should stop using exec.Command to build your child process command line, and build it yourself (as per rules described in the doco I mentioned). Then you can pass raw command line to your child process by setting exec.Cmd.SysProcAttr to syscall.SysProcAttr with CmdLine set appropriately.

Maybe we could fix this problem by changing Go encoding algorithm to use cmd.exe rules every time we execute batch file.

There is more of the same discussion on issue #15566.

Alex

[mattn]

I guess this should be fixed by small change.

diff --git a/src/syscall/exec_windows.go b/src/syscall/exec_windows.go
index cafce1e..a0e1f56 100644
--- a/src/syscall/exec_windows.go
+++ b/src/syscall/exec_windows.go
@@ -91,6 +91,9 @@ func makeCmdLine(args []string) string {
        }
        s += EscapeArg(v)
    }
+   if s != "" && s[0] == '"' && len(args) > 1 {
+       s = `"` + s + `"`
+   }
    return s
 }

If the first argument contain spaces, and it have arguments (no matter if the argument not contains spaces), whole of string should be quoted.

c:\dev\go-sandbox\space>go run main.go
Running: ".\\folder name\\test.bat" ""
Output: Success
Error: <nil>

Running: ".\\folder name\\test.bat" "one param"
Output: Success
Error: <nil>

[gopherbot]

CL https://golang.org/cl/32490 mentions this issue.

[rsc]

Postponing decisions about this to Go 1.9.

[basepack]

+1 This is still an issue here, also see: https://github.com/docker/machine/issues/3152

[alexbrainman]

@cannect docker/machine#3152 title mentions "powershell", but this issue is about running batch files. How do you know that if we make running batch file work, that it will fix docker/machine#3152 ?
Is there a simple way to reproduce docker/machine#3152 ?

Alex

[basepack]

As you can see here: https://github.com/docker/machine/issues/3152#issuecomment-261811531 there is some confidence we think it is related with this issue.

[alexbrainman]

@cannect do you know of a simple way to reproduce docker/machine#3152 ?
How did you personally discovered docker/machine#3152 ? Did you encountered that problem yourself?

Alex

[basepack]

Hi @alexbrainman ,

I had exact the same issues as described in the first post of docker/machine#3152.
I do not have the knowledge to reproduce that issue in Go. But I can tell you my steps:

• WIndows 10 Pro
• Docker for Windows
• Started two docker machines in Windows 10 bash, listed as active in docker-machine ls
• Looked those docker machines up with: docker-machine ls in Powershell, machines not active. (but they were active of course but not listed as such in Powershell)

Unfortunately I have no experience whatsoever with Go.

[alexbrainman]

@cannect thank you very much for these steps. But I have never used Docker for Windows. How do I install it and use it?

Docker for Windows

How do I install it? What are the steps?

Looked those docker machines up with: docker-machine ls in Powershell, machines not active. (but they were active of course but not listed as such in Powershell)

What are the commands I should run to reproduce this? What did you do? What did you expect to see? What did you see instead?

Thank you

Alex

[rsc]

I agree with https://github.com/golang/go/issues/17149#issuecomment-257518448 that the answer here should be to rewrite the path for argv[0] from using slash to backslash. We should try to fix this early in the Go 1.12 cycle.

[benlye]

Any progress on this issue?

I'd like to add that it only seems to be a problem when both the command and the parameter contain spaces. If only one or the other has a space then everything works. I've expanded on @calmh's example to demonstrate:

main.go:

package main

import (
    "fmt"
    "os/exec"
    "strings"
)

func main() {
    execCmd("C:/Users/blye/Go/src/github.com/benlye/cmdtest/folder name/test.bat")
    execCmd("C:/Users/blye/Go/src/github.com/benlye/cmdtest/folder name/test.bat", "oneparam")
    execCmd("C:/Users/blye/Go/src/github.com/benlye/cmdtest/folder name/test.bat", "one param")

    execCmd("C:/Users/blye/Go/src/github.com/benlye/cmdtest/foldername/test.bat")
    execCmd("C:/Users/blye/Go/src/github.com/benlye/cmdtest/foldername/test.bat", "oneparam")
    execCmd("C:/Users/blye/Go/src/github.com/benlye/cmdtest/foldername/test.bat", "one param")
    }

func execCmd(path string, args ...string) {
    fmt.Printf("Running: %q %q\n", path, strings.Join(args, " "))
    cmd := exec.Command(path, args...)
    bs, err := cmd.CombinedOutput()
    fmt.Printf("Output: %s", bs)
    fmt.Printf("Error: %v\n\n", err)
}

Produces only one failure (the 3rd test):

C:\Users\blye\Go\src\github.com\benlye\cmdtest>go run main.go
Running: "C:/Users/blye/Go/src/github.com/benlye/cmdtest/folder name/test.bat" ""
Output: Success
Error: <nil>

Running: "C:/Users/blye/Go/src/github.com/benlye/cmdtest/folder name/test.bat" "oneparam"
Output: Success
Error: <nil>

Running: "C:/Users/blye/Go/src/github.com/benlye/cmdtest/folder name/test.bat" "one param"
Output: 'C:/Users/blye/Go/src/github.com/benlye/cmdtest/folder' is not recognized as an internal or external command,
operable program or batch file.
Error: exit status 1

Running: "C:/Users/blye/Go/src/github.com/benlye/cmdtest/foldername/test.bat" ""
Output: Success
Error: <nil>

Running: "C:/Users/blye/Go/src/github.com/benlye/cmdtest/foldername/test.bat" "oneparam"
Output: Success
Error: <nil>

Running: "C:/Users/blye/Go/src/github.com/benlye/cmdtest/foldername/test.bat" "one param"
Output: Success
Error: <nil>

[alexbrainman]

Any progress on this issue?

I don't believe anyone working on this.

I'd like to add that it only seems to be a problem when both the command and the parameter contain spaces. ...

I am pretty sure we know what the problem is (see https://github.com/golang/go/issues/17149#issuecomment-248822918 for details). We just have not decided how to fix it.

Alex

[someblue]

For those stuck by this bug:

As https://github.com/golang/go/issues/17149#issuecomment-473976818 mentioned, this problem happened only when both binary path and arguments have space. So you can write a .bat file wrapping all arguments, and then run this .bat directly.

[kot0]

Why not fixed?

[bjg2]

Wow. What a bug. XD