How to I read cmd output in VB.NET from cmd shell?

Question

I am using gnokii to send out SMSes.

My VB Codes:

Dim xCmd As String
xCmd = "cmd.exe /c echo msgcontent "| c:\gnokii\gnokii.exe --sendsms 12345678"
Shell(xCmd)

Points to note:

I did try to redirect the output to a .txt file but the .txt file appears to be empty. Besides, the program may have to send out multiple SMSes every second, so creating a .txt is not feasible.
Process.Start() is not feasible because I have to check if gnokii.exe is running.
I need the output to check if the SMS is sent successfully.

I tried using (codes below), but it didn't work either; no output was shown.

Function exe(ByVal fileName, ByVal args)

Dim p As Process = New Process
Dim output As String

With p
    .StartInfo.CreateNoWindow = True
    .StartInfo.UseShellExecute = False
    .StartInfo.RedirectStandardOutput = True
    .StartInfo.FileName = fileName
    .StartInfo.Arguments = args
    .Start()
    output = .StandardOutput.ReadToEnd
End With

Return output

End Function

If you change your xCMD to have a > c:\xxx.txt does the content of xxx.txt contain the output you wanted? — BugFinder, Jun 18 '11 at 16:56
Maybe [this link](http://stackoverflow.com/questions/2162078/pick-up-strings-from-cmd-command-process-startinfo) will help. — Ken White, Jun 18 '11 at 17:39
Okay, hi all, yesterday I found an answer on how to save the output into the .txt file. Simply change "... > xxx.txt" to "... 2> xxx.txt" Thanks for all the help that was given :) — Joyce, Jun 19 '11 at 23:48
Just click `Answer Your Question` at the bottom of this page. — aligray, Jun 20 '11 at 00:17
OK, 2 is error out, not std out, thats why it wasnt working with other methods. — BugFinder, Jun 20 '11 at 10:41
@BugFinder yes, I always thought 2> and > was the same thing, so I didn't thought that the number mattered. — Joyce, Jul 02 '11 at 12:53

aligray · Answer 1 · 2011-06-19T03:57:25.977

3

Try this:

    Dim p As Process = New Process
    Dim output As String

    With p
        .StartInfo.CreateNoWindow = True
        .StartInfo.RedirectStandardOutput = True
        .StartInfo.UseShellExecute = False
        .StartInfo.FileName = fileName
        .StartInfo.Arguments = args
        .Start()
        output = .StandardOutput.ReadToEnd
        .WaitForExit()
    End With

    Return output

edited Jun 19 '11 at 03:57

answered Jun 19 '11 at 03:40

aligray

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Um, isn't that what I quoted.. lol, but still, thanks for the help :) – Joyce Jun 19 '11 at 23:50
Just seen this comment now after 9 years lol, the difference was `.WaitForExit()`. – aligray Mar 26 '20 at 14:06

score 1 · Accepted Answer · answered Jun 20 '11 at 00:24

To send output to a .txt file, (the best solution I can find)

REPLACE

xCmd = "cmd.exe /c echo msgcontent "| c:\gnokii\gnokii.exe --sendsms 12345678 > file.txt"

WITH

xCmd = "cmd.exe /c echo msgcontent "| c:\gnokii\gnokii.exe --sendsms 12345678 2> file.txt"

score 0 · Answer 3 · edited Feb 22 '13 at 23:51

You can use this 100% works but it will only show you the results

How to show shell results in vb.net:

'create 1 textbox1
'create 1 button1
'create 1 richtextbox1
'in the start up directory of this program make a file could 123.text
'------------------------------------------------------------------------
Dim read As System.IO.StreamReader
read = File.OpenText(Application.StartupPath & "\123.text")

Shell("cmd.exe /c" & TextBox1.Text + ">123.text")
Do Until read.EndOfStream
    RichTextBox1.Text = read.ReadLine & vbCrLf
Loop
'--------------------------------------------------------------------------
'you can add on the top to create the file if it does not exists,   

If IO.File.Exists(Application.StartupPath & "\123.text") = False Then
    IO.File.Create(Application.StartupPath & "\123.text")
End If
'-------------------------------------------------------------------------

The code is also available at this link http://pastebin.com/iEhv61jG

score 0 · Answer 4 · answered Feb 25 '14 at 19:28

I might suggest something like this, myself. This is similar to what someone else posted, but it offers a little more functionality, I think.

Imports System.IO
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Shell("cmd.exe /c " & TextBox1.Text + " > c:\temp\output.txt")
    Dim read As System.IO.StreamReader
    read = File.OpenText("c:\temp\output.txt")
    RichTextBox1.Clear()
    Do Until read.EndOfStream
        RichTextBox1.Text += read.ReadLine & vbCrLf
    Loop
    RichTextBox1.Select(RichTextBox1.Text.Length, 0)
    RichTextBox1.ScrollToCaret()
End Sub
End Class

How to I read cmd output in VB.NET from cmd shell?

4 Answers4