Pass more arguments to an already opened cmd prompt in C#

Question

I want to loop through all images in a folder, retrieve each image's name and pass an argument using the name. This is what I have:

foreach (string imageFile in Directory.EnumerateFiles(filePath))
{
    //Get image name and save it as string
    string args = "something"; //a line of argument with image name in it
    Process.Start("cmd", @"/c cd C:\Tesseract-OCR && " + args);
}

The problem with above code is that, for each image file, it will open up a new command prompt. Instead, I want something like:

Process.Start("cmd", @"/k cd C:\Tesseract-OCR");
foreach (string imageFile in Directory.EnumerateFiles(filePath))
{
    //For each imageFile I have, pass an argument to the opened cmd prompt
}

Answer 1

There are a few methods, but generally the simplest is to create a batch file with all of the commands you want to execute then pass that as a parameter to cmd .

Something like this:

string imageFolder = @"C:\Path\To\Images";
string batchFile = @"C:\Temp\cmds.cmd";
string outputFile = @"C:\Temp\cmds.log";

// substitute your own command here.  "{0}" will be substituted for filename 
string command = @"attrib ""{0}"" >> """ + outputFile + @"""";

// delete the batch file if it exists
if (File.Exists(batchFile))
    File.Delete(batchFile);

// create batch file from content of image folder
using (var writer = File.CreateText(batchFile))
{
    writer.WriteLine("@echo off");

    foreach (var file in Directory.EnumerateFiles(imageFolder, "*.jpg"))
        writer.WriteLine(command, file);
}

// Delete the output file if it exists
if (File.Exists(outputFile))
    File.Delete(outputFile);

// Execute the batch
var p = Process.Start("cmd", @"/c """ + batchFile + @"""");
p.WaitForExit();

After that completes you can grab the content of the output file and parse it for results. If you need a break between the outputs, just echo something distinctive between each one. Maybe something like:

// create batch file from content of image folder
using (var writer = File.CreateText(batchFile))
{
    writer.WriteLine("@echo off");

    foreach (var file in Directory.EnumerateFiles(imageFolder, "*.jpg"))
    {
        writer.WriteLine(@"echo -----Start: {0}>>""{1}""", file, outputFile);
        writer.WriteLine(command, file);
        writer.WriteLine(@"echo -----End: {0}>>""{1}""", file, outputFile);
    }
}

That way you get the filename in the output as well to help with parsing.

---

Another option is to use full stream redirection to streams that you can write commands to and read responses from. This would allow you to have a command prompt running somewhere in the background that you can issue commands to. Seems simple, but honestly it takes a lot of work to get just right. If you want to go this way I'd suggest redirecting all three standard streams.

Answer 2

为什么程序不创建包含所有要执行的文件/命令的批处理文件，然后使用Process.Start执行该批处理文件？

Answer 3

You can use Directory.GetFiles() to get a string array of all the files in a directory. Then use String.Join() to merge the array into one long string of file names separated by space. I would also wrap each item in quotes if your path or files contain spaces.

const string QUOTE = "\"";
const string SPACE = " ";
const string SEPARATOR = QUOTE + SPACE + QUOTE;

string[] files = Directory.GetFiles(filePath, "*.png");
string allFiles = QUOTE + String.Join(SEPARATOR, files) + QUOTE;
Console.WriteLine(@"cmd.exe /c cd C:\Tesseract-OCR && " + allFiles);