I want to call some cmd prompt commands from a .net C# application. However before the command is run I need to set up a varaibles within a batch file. Is there a way to maintain the variables to subsequent calls to the command prompt?
I provide an example below of the problem.
Say I have a simple batch file C:\setEnv.bat containing
set notepad=C:\windows\system32\notepad.exe
Then if I have C# code like thus:
var proc1 = new ProcessStartInfo();
string cmd1 = #"CALL C:\setEnv.bat";
string cmd2 = #"ECHO notepad=%notepad%>C:\test.txt";
proc1.UseShellExecute = true;
var process = new Process();
var startInfo = new ProcessStartInfo();
startInfo.WindowStyle = ProcessWindowStyle.Hidden;
startInfo.FileName = "cmd.exe";
startInfo.Arguments = "/C " +cmd1;
process.StartInfo = startInfo;
process.Start();
process.WaitForExit();
startInfo.Arguments = "/C " + cmd2;
process.Start();
process.WaitForExit();
Now I'm guessing that the /C is terminating the command prompt thus losing my variables but if I don't have it then the cmd prompt doesn't return after finishing the command.
I thought I could double the cmd1 & cmd2 to a single call but then I would need to do that for every call to the cmd prompt and feels a little redundant calling C:\setenv.bat again and again.
You may use way in this question
For example, use command "set" in cmd1:
string cmd1 = "\" CALL C:\\setEnv.bat && set \"";
startInfo.RedirectStandardOutput = true;
startInfo.UseShellExecute = false;
//...
process.Start();
string variables = process.StandardOutput.ReadToEnd();
// next parse variables string
And before start second process set parsed variables in "startInfo.EnvironmentVariables"
A few issues/ideas:
1) How many values to you need to track from one execution to the next? Primarily, can you just use the errorlevel return value or do you need more details?
2) Can you pipe the results of the first directly into the second as one call?
3) Can you output the values from the first call to a file and in the 2nd call, pipe that as input into the 2nd cmd?
4) I assume that you have some processing that is done after the first cmd is run, but before the 2nd cmd is called. Could you create an .exe that can be called by the 1st batch file (after the other code) that does that processing. That way, you have 3 cmds all of which can be run in the same environment and your variables stick around.
Related
I'm trying to read all system information on a windows pc, using C#. Here is my code :
public static string GetSystemInfo()
{
String command = "systeminfo";
ProcessStartInfo cmdsi = new ProcessStartInfo("cmd.exe");
cmdsi.Arguments = command;
Process cmd = Process.Start(cmdsi);
cmd.WaitForExit();
return cmd.StandardOutput.ReadToEnd();
}
But it just opens a console, doesn't execute systeminfo command.
How this can be solved?
The following snippet will work
public static string GetSystemInfo()
{
var command = "/c systeminfo";
var cmdsi = new ProcessStartInfo("cmd.exe");
cmdsi.Arguments = command;
cmdsi.RedirectStandardOutput = true;
cmdsi.UseShellExecute = false;
var cmd = Process.Start(cmdsi);
var output = cmd.StandardOutput.ReadToEnd();
cmd.WaitForExit();
return output;
}
You should set RedirectStandardOutput to true and read output before calling WaitForExit, otherwise you can get a deadlock, per MSDN
The example avoids a deadlock condition by calling
p.StandardOutput.ReadToEnd before p.WaitForExit. A deadlock condition
can result if the parent process calls p.WaitForExit before
p.StandardOutput.ReadToEnd and the child process writes enough text to
fill the redirected stream. The parent process would wait indefinitely
for the child process to exit.
/c means terminating command line after execution
You need to prepend "/c" to the command
String command = "/c systeminfo";
/c indicates that you want to execute a command that follows
Update
ProcessStartInfo.RedirectStandardOutput needs to be set to true as mentioned in Pavel's Answer.
I'm having some difficulty doing this without using a batch file. What I want to do is when a button is clicked, run the command line with a simple argument that I specify.
Here's my code so far:
ProcessStartInfo startInfo = new ProcessStartInfo("cmd.exe");
startInfo.WindowStyle = ProcessWindowStyle.Normal;
startInfo.UseShellExecute = true;
startInfo.Arguments = "dir";
Process.Start(startInfo);
string output = Process.StandardOutput.ReadToEnd();
txtblkOutput.Text = output;
However, this just opens a cmd window and nothing happens. The text box remains blank.
However I can do this:
var process = new Process();
process.StartInfo.FileName = "C:/Users/user/Documents/SUB-20 Tool/commands.bat";
process.StartInfo.UseShellExecute = false;
process.StartInfo.RedirectStandardOutput = true;
process.Start();
string output = process.StandardOutput.ReadToEnd();
txtblkOutput.Text = output;
Inside the batch file it just says dir. And this works, I get the output sent to my textbox.
Why does this work only with a batch file? Can I do this without it, with just using the argument property?
This is the excepted behaviour. When you execute cmd.exe with the argument dir, it does not execute the command.
As an exemple, see the screenshot below :
The correct way to execute a command in the arguments is the following :
cmd.exe /C <command>
Here is my code:
try
{
ProcessStartInfo procStartInfo = new ProcessStartInfo(
"cmd.exe",
"/c " + command);
procStartInfo.UseShellExecute = true;
procStartInfo.CreateNoWindow = true;
procStartInfo.Verb = "runas";
procStartInfo.Arguments = "/env /user:" + "Administrator" + " cmd" + command;
///command contains the command to be executed in cmd
System.Diagnostics.Process proc = new System.Diagnostics.Process();
proc.StartInfo = procStartInfo;
proc.Start();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
I want to keep
procStartInfo.UseShellExecute = true
procStartInfo.RedirectStandardInput = false;
Is it possible to execute the command without using process.standardinput?
I try to execute command I've passed in argument but the command does not executes.
As #mtijn said you've got a lot going on that you're also overriding later. You also need to make sure that you're escaping things correctly.
Let's say that you want to run the following command elevated:
dir c:\
First, if you just ran this command through Process.Start() a window would pop open and close right away because there's nothing to keep the window open. It processes the command and exits. To keep the window open we can wrap the command in separate command window and use the /K switch to keep it running:
cmd /K "dir c:\"
To run that command elevated we can use runas.exe just as you were except that we need to escape things a little more. Per the help docs (runas /?) any quotes in the command that we pass to runas need to be escaped with a backslash. Unfortunately doing that with the above command gives us a double backslash that confused the cmd parser so that needs to be escaped, too. So the above command will end up being:
cmd /K \"dir c:\\\"
Finally, using the syntax that you provided we can wrap everything up into a runas command and enclose our above command in a further set of quotes:
runas /env /user:Administrator "cmd /K \"dir c:\\\""
Run the above command from a command prompt to make sure that its working as expected.
Given all that the final code becomes easier to assemble:
//Assuming that we want to run the following command:
//dir c:\
//The command that we want to run
string subCommand = #"dir";
//The arguments to the command that we want to run
string subCommandArgs = #"c:\";
//I am wrapping everything in a CMD /K command so that I can see the output and so that it stays up after executing
//Note: arguments in the sub command need to have their backslashes escaped which is taken care of below
string subCommandFinal = #"cmd /K \""" + subCommand.Replace(#"\", #"\\") + " " + subCommandArgs.Replace(#"\", #"\\") + #"\""";
//Run the runas command directly
ProcessStartInfo procStartInfo = new ProcessStartInfo("runas.exe");
procStartInfo.UseShellExecute = true;
procStartInfo.CreateNoWindow = true;
//Create our arguments
string finalArgs = #"/env /user:Administrator """ + subCommandFinal + #"""";
procStartInfo.Arguments = finalArgs;
//command contains the command to be executed in cmd
using (System.Diagnostics.Process proc = new System.Diagnostics.Process())
{
proc.StartInfo = procStartInfo;
proc.Start();
}
why are you initializing the process object with arguments and then later on override those Arguments? and btw: the last bit where you set Arguments you concatenate 'command' right upto 'cmd', that doesn't make much sense and might be where it fails (looks like you're missing a space).
Also, you are currently using the standard command line, you might want to look into using the runas tool instead. you can also call runas from command line.
Also, why are you running 'command' from the command line? why not start it directly from Process.Start with admin privileges supplied then and there? here's a bit of pseudocode:
Process p = Process.Start(new ProcessStartInfo()
{
FileName = <your executable>,
Arguments = <any arguments>,
UserName = "Administrator",
Password = <password>,
UseShellExecute = false,
WorkingDirectory = <directory of your executable>
});
I am new to C# so please sorry if i make no sense in my question. In my application which is C# DLL need to open command prompt, give a plink command for Linux system to get a system related string and set that string as environment variable. I am able to do this when i create C# console application, using plink command to get the string on command prompt and use to set it environment variable using process class in C# to open plink as separate console process. But, in C# DLL i have to open cmd.exe 1st and then give this command which i don't know how can i achieve? I tried through opening cmd.exe as process and then trying to redirect input and output to process and give command and get string reply, but no luck. Please let me know any other way to solve this.
Thanks for answers,
Ashutosh
Thanks for your quick replys. It was my mistake in writing code sequence. Now few changes and the code is working like charm. Here is code,
string strOutput;
//Starting Information for process like its path, use system shell i.e. control process by system etc.
ProcessStartInfo psi = new ProcessStartInfo(#"C:\WINDOWS\system32\cmd.exe");
// its states that system shell will not be used to control the process instead program will handle the process
psi.UseShellExecute = false;
psi.ErrorDialog = false;
// Do not show command prompt window separately
psi.CreateNoWindow = true;
psi.WindowStyle = ProcessWindowStyle.Hidden;
//redirect all standard inout to program
psi.RedirectStandardError = true;
psi.RedirectStandardInput = true;
psi.RedirectStandardOutput = true;
//create the process with above infor and start it
Process plinkProcess = new Process();
plinkProcess.StartInfo = psi;
plinkProcess.Start();
//link the streams to standard inout of process
StreamWriter inputWriter = plinkProcess.StandardInput;
StreamReader outputReader = plinkProcess.StandardOutput;
StreamReader errorReader = plinkProcess.StandardError;
//send command to cmd prompt and wait for command to execute with thread sleep
inputWriter.WriteLine("C:\\PLINK -ssh root#susehost -pw opensuselinux echo $SHELL\r\n");
Thread.Sleep(2000);
// flush the input stream before sending exit command to end process for any unwanted characters
inputWriter.Flush();
inputWriter.WriteLine("exit\r\n");
// read till end the stream into string
strOutput = outputReader.ReadToEnd();
//remove the part of string which is not needed
int val = strOutput.IndexOf("-type\r\n");
strOutput = strOutput.Substring(val + 7);
val = strOutput.IndexOf("\r\n");
strOutput = strOutput.Substring(0, val);
MessageBox.Show(strOutput);
I explained the code so far..., thanks a lot
System.Diagnostics.Process proc0 = new System.Diagnostics.Process();
proc0.StartInfo.FileName = "cmd";
proc0.StartInfo.WorkingDirectory = Path.Combine(curpath, "snd");
proc0.StartInfo.Arguments = omgwut;
And now for some background...
string curpath = System.IO.Path.GetDirectoryName(Application.ExecutablePath);
omgwut is something like this:
copy /b a.wav + b.wav + ... + y.wav + z.wav output.wav
And nothing happens at all. So obviously something's wrong. I also tried "copy" as the executable, but that doesn't work.
Try the prefixing your arguments to cmd with /C, effectively saying cmd /C copy /b t.wav ...
According to cmd.exe /? using
/C <command>
Carries out the command specified by
string and then terminates
For your code, it might look something like
// ..
proc0.StartInfo.Arguments = "/C " + omgwut;
Notes:
A good way to test whether your command is going to work is to actually try it from a command prompt. If you try to do cmd.exe copy ... you'll see that the copy doesn't occur.
There are limits to the length of the arguments you can pass as arguments. From MSDN: "The maximum string length is 2,003 characters in .NET Framework applications and 488 characters in .NET Compact Framework applications."
You can bypass the shelling out to command by using the System.IO classes to open the files and manually concatenate them.
Try this it might help you.. Its working with my code.
System.Diagnostics.ProcessStartInfo procStartInfo =
new System.Diagnostics.ProcessStartInfo("cmd", "/c " + command);
// The following commands are needed to redirect the standard output.
// This means that it will be redirected to the Process.StandardOutput StreamReader.
procStartInfo.RedirectStandardOutput = true;
procStartInfo.UseShellExecute = false;
// Do not create the black window.
procStartInfo.CreateNoWindow = true;
// Now we create a process, assign its ProcessStartInfo and start it
System.Diagnostics.Process proc = new System.Diagnostics.Process();
proc.StartInfo = procStartInfo;
proc.Start();
// Get the output into a string
string result = proc.StandardOutput.ReadToEnd();
// Display the command output.
Console.WriteLine(result);
}
catch (Exception objException)
{
// Log the exception
}
Even you can try this.. this is even better.
System.Diagnostics.Process proc = new System.Diagnostics.Process();
proc.EnableRaisingEvents=false;
proc.StartInfo.FileName="iexplore";
proc.StartInfo.Arguments="http://www.microsoft.com";
proc.Start();
proc.WaitForExit();
MessageBox.Show("You have just visited " + proc.StartInfo.Arguments);
Daniels cmd /c idea will work. Keep in mind there is a limit to the length of a command line probably 8k in your case see this for details.
Since you are in a .Net app anyway, File.Copy may be quite a bit easier/cleaner than this approach.