Providing input to a child process

There are two methods you can use to provide input to a child process: set cmd.Stdin to a stream or use cmd.StdinPipe to obtain a writer to send the input to the child process.

How to do it...

1. Create the command:

   // Run grep and search for a word
   cmd := exec.Command("grep", word)

2. Provide the input to the process by setting the Stdin stream:

   // Open a file
   input, err := os.Open("input.txt")
   if err != nil {
     panic(err)
   }
   cmd.Stdin = input

3. Run the program and wait for it to end:

   if err = cmd.Start(); err != nil {
     panic(err)
   }
   if err = cmd.Wait(); err != nil {
     panic(err)
   }

   Alternatively, you can provide a streaming input using a pipe.

4. Create the command:

   // Run grep and search for a word
   cmd := exec.Command("grep", word)

5. Get the input pipe:

   input, err:=cmd.StdinPipe()
   if err!=nil {
     panic(err)
   }

6. Send the input to the program through the pipe. When done, close...