How to use command lines in vb.net

Imports System
Imports System.IO
Imports System.Diagnostics.Process
Imports System.Diagnostics.ProcessStartInfo

Public Class EDCS

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim dlgrslt As DialogResult = OpenFileDialog1.ShowDialog()
        Dim fnames As String() = OpenFileDialog1.FileNames
        Dim txtfnames As String

        For i = 0 To fnames.Length - 1
            If TextBox1.Text = "" Then
                TextBox1.Text = fnames(i)
            Else
                TextBox1.Text = TextBox1.Text + " / " + fnames(i)
            End If
            txtfnames = fnames(i).Replace(".pdf", ".txt")
            File.Create(txtfnames).Dispose()

            Dim convertcommand As String = "textextract """ & fnames(i) & """ /to """ & txtfnames & """"
            
            '/c will exit cmd and /k will keep it open
            'Shell("cmd.exe /c textextract "C:\Users\user\Desktop\ Part 1.pdf" /to " C:\Users\user\Desktop\ Part 1.txt"")

            'SendKeys.Send(convertcommand)
            'SendKeys.Send("{ENTER}")
            
            Dim p As New Process
            p.StartInfo.FileName = "cmd.exe"
            'p.StartInfo.WorkingDirectory = "C:\Program Files (x86)\Two Pilots\PDF2Text Pilot"
            p.StartInfo.Arguments = "textextract "C:\Users\user\Desktop\ Part 1.pdf" /to " C:\Users\user\Desktop\ Part 1.txt""
            p.StartInfo.UseShellExecute() = False
            p.StartInfo.RedirectStandardInput = True
            p.StartInfo.RedirectStandardOutput = True
            p.Start()
            

            'Dim process As New Process()
            'process.StartInfo.FileName = "cmd.exe "
            'process.StartInfo.Verb = "runas"
            'process.StartInfo.UseShellExecute = False
            'process.StartInfo.RedirectStandardInput = True
            'process.StartInfo.RedirectStandardOutput = True
            'process.Start()

            'process.StandardInput.WriteLine("textextract "C:\Users\user\Desktop\ Part 1.pdf" /to " C:\Users\user\Desktop\ Part 1.txt"")
            'process.StandardInput.WriteLine("exit")
            'process.Close()

                  Next
    End Sub
End Class