runtime: Problem parsing on single quotes in argument for Process.Start (dotnet Core, Linux console)

(2019-07-21: rewrote this issues to simplify)

I’m executing console programs in Linux using

I’m executing programs on Linux with Process.Start. Sometimes I need to provide single quotes in the arguments but I’ve not been able to succeed no matter how I escape the character. A simplified example:

using System;
using System.Diagnostics;

namespace Execute_test
{
    class Program
    {
        static void Main(string[] args)
        {
            Process proc = new System.Diagnostics.Process();
            ProcessStartInfo pi = new ProcessStartInfo("ls");
            pi.Arguments = "-l '/tmp/'";
            proc.StartInfo = pi;
            proc.Start();
            do { System.Threading.Thread.Sleep(50); } while (proc.HasExited == false);
            Environment.Exit(0);
        }
    }
}

I do know I don’t have to surround /tmp/ in single quote, but it’s just to make a simple example (please don’t suggest alternatives, that’s not the issue!) The err.out from this example is ls: cannot access "'/tmp/'": No such file or directory

I’ve tried to run this code in .net Core 2.2 and the newest .net Core 3.0.100-preview6-012264 in both C# and VB.

I also tried to use the ProcessStartInfo.ArgumentList it doesn’t parse single quotes any better.

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 29 (10 by maintainers)

Most upvoted comments

OMG!!! ProcessStartInfo pi = new ProcessStartInfo("ls"){ ArgumentList = {"'","/tmp/","'"} }; Pure beauty, thaaaaanks

MrM40 on Jul 23, 2019

@jnm2 I’m confused, shouldn’t it be

ArgumentList = { "-W", "-f= ${db:Status-Status} ", "mariadb*" }

and

ArgumentList = { "qemu-agent-command", "SRV01", "{\"execute\":\"guest-ping\"}" }?

If you execute dpkg-query -W -f=' ${db:Status-Status} ' mariadb* in bash, the ' are not passed to the executable, as you can easily test by putting printf '%s\n' before the commands. Running printf '%s\n' dpkg-query -W -f=' ${db:Status-Status} ' mariadb* in bash gives

dpkg-query
-W
-f= ${db:Status-Status}
mariadb*

as output, so ' is not contained in the arguments, if dpkg-query -W -f=' ${db:Status-Status} ' mariadb* is executed in bash.

TSlivede on Jul 23, 2019

@MrM40 ~~Why aren’t you doing ArgumentList = { "-W", "-f=' ${db:Status-Status} '", "mariadb*" }?~~

~~And ArgumentList = { "qemu-agent-command", "SRV01", "'{\"execute\":\"guest-ping\"}'" }?~~

jnm2 on Jul 23, 2019

    class Program
    {
        static void Main(string[] args)
        {
            Process proc = new System.Diagnostics.Process();
            ProcessStartInfo pi = new ProcessStartInfo("sh"){
                ArgumentList = {
                    "-c",
                    "ls '/tmp/'" 
                }
            };
            proc.StartInfo = pi;
            proc.Start();
            do { System.Threading.Thread.Sleep(50); } while (proc.HasExited == false);
            Environment.Exit(0);
        }
    }

works fine for me. If you want ' to be considered a quote, you need some executable, that considers it a quote - for example sh or bash.

TSlivede on Jul 23, 2019

You want to start the application from .NET Core which you start on the command line as:

$ /bin/bash -c 'ls -l /etc/ > /tmp/list.txt'

Let’s first figure out how many arguments are involved when starting the application. We’ll use strace and trace for the execve call:

$ strace -e execve -qq /bin/bash -c 'ls -l /etc/ > /tmp/list.txt'
execve("/bin/bash", ["/bin/bash", "-c", "ls -l /etc/ > /tmp/list.txt"], 0x7ffe1e57c978 /* 71 vars */) = 0

As we can see in the output, two arguments are passed to bash: -c and ls -l /etc/ > /tmp/list.txt.

We need a way of passing the second argument so it gets treated as a whole (that is, not split at the spaces).

For bash, there are a number of options. One is to use single quotes, like /bin/bash -c 'ls -l /etc/ > /tmp/list.txt'.

For ProcessStartInfo.Arguments, we need to use double quotes.

static void Main(string[] args)
{
    Process.Start(
        new ProcessStartInfo
        {
            FileName = "/bin/bash",
            Arguments = "-c \"ls -l /etc/ > /tmp/list.txt\""
        }
    ).WaitForExit();

    if (File.Exists("/tmp/list.txt"))
    {
        System.Console.WriteLine("The file exists!");
    }
}

prints out:

The file exists!

tmds on Mar 26, 2019

ProcessStartInfo pi = new ProcessStartInfo("ls"){ ArgumentList = {"/tmp/"} }; is enough - you don’t need a ' in that case.

If you execute ls -l '/tmp/' '/path/with space/' in bash or sh, then ls never sees any ' - they are removed by the calling shell. ls just gets an array of

ls
-l
/tmp/
/path/with space/

TSlivede on Jul 23, 2019

No no no! This is equivalent of executing ls "'" "/tmp/" "'" in bash. It works, but does not do what you want. It lists the files of a folder named ' (twice) and lists the contents of /tmp/.

Please delete (or edit) your comment https://github.com/dotnet/corefx/issues/23592#issuecomment-514241549 as it could heavily confuse newcomers.

TSlivede on Jul 23, 2019

.NET Core added an ArgumentsList on ProcessStartInfo. You don’t need to deal with escaping if you are using that. You can Add the ‘-c’ and ‘ls -l /etc/ > /tmp/list.txt’ to the ArgumentsList.

tmds on Feb 21, 2019