In this post, I document three examples on how we can interface with other applications via command line in C#.<\/p>\n
Start a web browser to display a webpage from C#<\/h3>\n
Let's start off with a minimal example. Let's assume that I wish to show my website from my C# program.<\/p>\n
That would be a similar to typing That is actually an example of command line execution. We are actually requesting the operating system to start a process<\/strong> to run The following code segment is how we could do that in C#:<\/p>\n This code segment began with creating an instance of the The name of the application (iexplore) to start on command line is then set via the When the relevant start up information<\/strong> is provided via the When we get our Unless our C# program is able to serve HTTP requests<\/a> and we point internet explorer to its url, we are not interacting with the internet explorer process anymore in our previous code example.<\/p>\n However, there are times when we want to read the standard output of an application that we started from command line. <\/p>\n The following code segment demonstrates how we can read from the standard output of the ipconfig<\/a> command:<\/p>\n In this case, we are getting our C# program to execute As with the internet explorer example, the above program first creates an instance of In addition to that, two other properties are being set - We set When start information about the process had been provided to the Finally, we get a Sometimes, our C# program will need to interact with command line applications that collect input from the user through a command line interface. To interact with such application, we need to write to the standard input of the command line application.<\/p>\n Let's assume we have the following command line application, And right now, we want to interface with it from another C# program. The following code demonstrates how we can do so by writing to the standard input and reading from the standard output of Similar to the first two examples, the program begins with creating an instance of the Four pieces of start information are then supplied to the The process is then started with a call to the After the process had started, we first get an instance of We then use the StreamReader instance to read the prompt for name input from Greeter.exe, write Robot to its Standard Input and read its response, which is the string \"Hello Robot. Nice to meet you!\". <\/p>\n As with most programming languages, C# has the facilities to start other applications via command line. Such facilities may not be of much interest to the ardent C# programmer, who will want to fulfill every business logic with purely C# codes in his\/her program. However, there are times when it is necessary to interface with applications that other people had already built for us.<\/p>\n","protected":false},"author":1,"featured_media":1189,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"footnotes":""},"categories":[375],"tags":[20,99,84,97],"jetpack_featured_media_url":"https:\/\/www.techcoil.com\/blog\/wp-content\/uploads\/C-Sharp-Logo.gif","jetpack_shortlink":"https:\/\/wp.me\/p245TQ-2J","jetpack-related-posts":[],"jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/posts\/169"}],"collection":[{"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/comments?post=169"}],"version-history":[{"count":0,"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/posts\/169\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/media\/1189"}],"wp:attachment":[{"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/media?parent=169"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/categories?post=169"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.techcoil.com\/blog\/wp-json\/wp\/v2\/tags?post=169"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}iexplore http:\/\/www.techcoil.com<\/code> in the command prompt to start internet explorer to show the home page of my website.<\/p>\nWhat happens when we do that?<\/h4>\n
iexplore<\/code> (the executable for Internet Explorer), giving it http:\/\/www.techcoil.com<\/code> as a command line argument<\/strong>.<\/p>\n\r\nusing System;\r\nusing System.Diagnostics;\r\nusing System.Text;\r\npublic class LaunchInternetExplorer\r\n{\r\n public static void Main(string[] args)\r\n {\r\n Process ieProcess = new Process();\r\n \/\/ Set the application that our Process is\r\n \/\/ going to start.\r\n ieProcess.StartInfo.FileName = "iexplore";\r\n \/\/ Pass in the url that iexplore will visit upon\r\n \/\/ starting as a command line argument.\r\n ieProcess.StartInfo.Arguments = "http:\/\/www.techcoil.com";\r\n \/\/ Start the command line execution\r\n ieProcess.Start();\r\n } \/\/ public static void Main(string[] args)\r\n} \/\/ end public class LaunchInternetExplorer\r\n<\/pre>\nSystem.Diagnostic.Process<\/code><\/a> class.<\/p>\nieProcess.StartInfo.FileName<\/code> property. After that, the url to techcoil is provided as a command line argument via the ieProcess.StartInfo.Arguments<\/code> property.<\/p>\nieProcess.StartInfo<\/code> property, we start the process to launch internet explorer by calling ieProcess.Start()<\/code>.<\/p>\nSo what is
ieProcess.StartInfo<\/code>?<\/h4>\nProcess<\/code> instance, we also get an instance of the System.Diagnostics.ProcessStartInfo<\/code><\/a>, which contains startup information for the process when it starts running. This ProcessStartInfo<\/code> instance is accessible via the StartInfo<\/code><\/a> property of our Process instance.<\/p>\nReading from standard output of command line application in C#<\/h3>\n
\r\nusing System;\r\nusing System.Diagnostics;\r\nusing System.IO;\r\nusing System.Text;\r\npublic class ReadFromStandardOutput\r\n{\r\n public static void Main(string[] args)\r\n {\r\n Process ipconfigProcess = new Process();\r\n \/\/ Indicate that we want to execute ipconfig\r\n ipconfigProcess.StartInfo.FileName = "ipconfig";\r\n ipconfigProcess.StartInfo.Arguments = "\/all";\r\n \/\/ Indicate that we want to read the command line output\r\n ipconfigProcess.StartInfo.RedirectStandardOutput = true;\r\n ipconfigProcess.StartInfo.UseShellExecute = false;\r\n \/\/ Start the process to execute ipconfig\r\n ipconfigProcess.Start();\r\n \/\/ Get a StreamReader to read from the standard output of\r\n \/\/ the ipconfig process\r\n StreamReader reader = ipconfigProcess.StandardOutput;\r\n \/\/ Perform reading and writing of standard output to Console\r\n String line;\r\n while((line = reader.ReadLine()) != null) {\r\n Console.WriteLine(line);\r\n } \/\/ end while\r\n } \/\/ end public static void Main(string[] args)\r\n} \/\/ end public class ReadFromStandardOutput\r\n<\/pre>\nipconfig \/all<\/code>, which will display current TCP\/IP network configurations for all adapters in our windows machine.<\/p>\nProcess<\/code> and then supplies it with the application name to run and a command line argument string.<\/p>\nStartInfo.RedirectStandardOutput<\/code><\/a> and StartInfo.UseShellExecute<\/code><\/a>.<\/p>\nRedirectStandardOutput<\/code> to true because we want to be able to read from standard output; set UseShellExecute<\/code> to false because we cannot use<\/strong> the operating system shell to execute the command line application if we want to get its standard output.<\/p>\nProcess<\/code> instance, we start the process to execute ipconfig \/all<\/code> via command line.<\/p>\nSystem.IO.StreamReader<\/code><\/a> instance from the StandardOutput property and use it to read the standard output, just like how we would read text from file<\/a>.<\/p>\nWriting to standard input of command line application in C#<\/h3>\n
Greeter.exe<\/code>, that greets the user after asking for his\/her name:<\/p>\n\r\npublic class Greeter\r\n{\r\n public static void Main(string[] args)\r\n {\r\n Console.WriteLine("What's your name? ");\r\n String name = Console.ReadLine();\r\n Console.WriteLine("Hello " + name + ". Nice to meet you!");\r\n } \/\/ end public static void Main(string[] args)\r\n} \/\/ end public class Greeter\r\n<\/pre>\nGreeter.exe<\/code>.<\/p>\n\r\npublic class WriteToStandardInputOfGreeter\r\n{\r\n public static void Main(string[] args)\r\n {\r\n Process greeterProcess = new Process();\r\n greeterProcess.StartInfo.FileName = "Greeter.exe";\r\n \/\/ Indicate that we want to read from standard output\r\n \/\/ of process\r\n greeterProcess.StartInfo.RedirectStandardInput = true;\r\n \/\/ Indicate that we want to write to standard input of\r\n \/\/ process\r\n greeterProcess.StartInfo.RedirectStandardOutput = true;\r\n greeterProcess.StartInfo.UseShellExecute = false;\r\n greeterProcess.Start();\r\n \/\/ Get a StreamWriter to write to the standard input of\r\n \/\/ Greeter.exe\r\n StreamWriter writer = greeterProcess.StandardInput;\r\n \/\/ Get a StreamReader to read from standard output of\r\n \/\/ Greeter.exe\r\n StreamReader reader = greeterProcess.StandardOutput;\r\n \/\/ Get the question from greeter\r\n Console.WriteLine("Question from greeter: ");\r\n Console.WriteLine(reader.ReadLine());\r\n \/\/ Answer Greeter with Robot\r\n writer.WriteLine("Robot");\r\n Console.WriteLine("Response from greeter: ");\r\n Console.WriteLine(reader.ReadLine());\r\n } \/\/ end public static void Main(string[] args)\r\n} \/\/ end public class WriteToStandardInputOfGreeter\r\n<\/pre>\nProcess<\/code> class.<\/p>\nProcess<\/code> instance:<\/p>\n\n
StartInfo.FileName<\/code> property.<\/li>\nStartInfo.RedirectInputOutput<\/code> property.<\/li>\nStartInfo.RedirectStandardOutput<\/code> property.<\/li>\nStartInfo.UseShellExecute<\/code> property, so that our C# program can read from the standard output and write to the standard input of Greeter.exe<\/code>.<\/li>\n<\/ol>\ngreeterProcess.Start<\/code>.<\/p>\nStreamReader<\/code> via the greeterProcess.StandardOutput<\/code> property and an instance of System.IO.StreamWriter<\/code><\/a> via the greeterProcess.StandardInput<\/code> property.<\/p>\nPosts that may interest you<\/h3>\n
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