Re: How to Use Shell command for DOS Commands
From: Rick Rothstein (rickNOSPAMnews_at_NOSPAMcomcast.net)
Date: 02/10/04
- Next message: Brian E: "reading MS outlook files"
- Previous message: Rick Rothstein: "Re: Rich TextBox"
- In reply to: Pankaj Khapre Technical Consultant: "How to Use Shell command for DOS Commands"
- Messages sorted by: [ date ] [ thread ]
Date: Tue, 10 Feb 2004 13:10:29 -0500
> I want to execute following dos command through VB6.0, using shell
> c:\Dir *.txt > ListofTextfiles.txt
> If you execute the above command on dos prompt , it will create a
> file ListofTextfiles.txt having list of all txt files on C drive. But,
> if i want to execute the same command through VB using shell , it
> gives error.
> Any comments ? How to achieve this using VB??
The following is a compilation of several posts I've given in the past
regarding the Shell command. Your question is addressed in there; the
remainder is for your consideration.
Rick -MVP
You can use the Shell command. To execute internal DOS command (Dir, Copy,
etc. as well as redirection of screen output), the command processor must be
specified (using the Environ$ function and "comspec" as its argument returns
the correct command processor path on NT and non-NT systems) . Specifying
the command processor is safe & generic and will work with non-internal
commands also. That syntax, using an XCopy command as an example is:
Shell Environ$("comspec") & " /c xcopy """ & _
Source & """ """ & Destination & """ " & Option, vbHide
You set the Source and Desination (string variables) to the appropriate
paths and the Option (string variable), if any, which can be found by
opening an MSDOS Prompt window and typing xcopy /?. (Note: You can type /?
after any DOS command at a DOS prompt to list the available options for that
command.) One more example would be to list all the files in a directory
including subdirectories and subdirectories of subdirectories and all of
their files.
CommandLine = "dir """ & FileSpec & _
""" /s/b > """ & RedirectTo & """"
Shell Environ$("comspec") & " /c " & CommandLine, vbHide
Here, the output of a Dir command is redirected to a file-path you specify
in the RedirectTo (string variable). The /s/b are options to the Dir command
that tell it to recurse throught its subdirectories and not to include
header or summary information.
I used a variable for the file name so that I could more easily explain the
benefit of encasing it in quotemarks. If you redirect to a file that has
spaces in its name, or if there are spaces in the path specification itself,
then the filename *must* be quoted to protect the spaces from DOS's desire
to use them as delimiters. (That's what all those quotemarks in the Shell
statement are for.) If the filename doesn't have spaces in it, the quotes
aren't necessary BUT they don't hurt either. Hence, the above will work with
either.
As for your PING question, something like the following should work:
strIP = "4.17.23.1"
Shell Environ$("comspec") & " /c ping " & _
strIP & " > """ & RedirectFile & """", vbHide
Although you didn't specify it in your original post, I assume you want to
use vbHide for the optional 2nd parameter to Shell. This hides the DOS
window so that your user doesn't see it. If you want the DOS window to
remain visible, you would use the vbNormalFocus BUT you must use a /k
instead of a /c for the command processor argument. Basically, the /c tells
the command processor "here comes a command and, when its finished
executing, close the DOS shell it is running in" whereas the /k also tells
the command processor that a command follows, but it instructs it to leave
the DOS session running.
The above assumes you do NOT have to wait for this file to be completely
written before your code continues executing. If you have to work with this
file right after it is created, consider one of these (which makes your
program wait until the DOS process is finished):
MICROSOFT 'S OFFICIAL WAY
========================
See this link
http://support.microsoft.com/support/kb/articles/Q129/7/96.asp
Note: This method doesn't use Shell -- it uses CreateProcessA.
FAST AND DIRTY METHOD (WORKS ALMOST ALL THE TIME)
=================================================
Paste these lines in the (General)(Declarations) section of the form where
the Shell is being called (or remove the Private keywords and put them in a
BAS module if more than one form will use them):
Private Declare Function OpenProcess _
Lib "kernel32" _
(ByVal dwDesiredAccess As Long, _
ByVal bInheritHandle As Long, _
ByVal dwProcessId As Long) As Long
Private Declare Function CloseHandle _
Lib "kernel32" _
(ByVal hObject As Long) As Long
Private Declare Function WaitForSingleObject _
Lib "kernel32" _
(ByVal hHandle As Long, _
ByVal dwMilliseconds As Long) As Long
Call your Shell command in this form with the appropriate Shell arguments
placed in the parentheses:
PID = Shell( <<Put Shell Arguments Here>> )
And finally, paste the following IMMEDIATELY after the PID=Shell statement
above (making sure to handle the possible error where indicated; i.e. stop
the code from falling through to your other commands if the Shell failed):
If PID = 0 Then
'
'Handle Error, Shell Didn't Work
'
Else
hProcess = OpenProcess(&H100000, True, PID)
WaitForSingleObject hProcess, -1
CloseHandle hProcess
End If
- Next message: Brian E: "reading MS outlook files"
- Previous message: Rick Rothstein: "Re: Rich TextBox"
- In reply to: Pankaj Khapre Technical Consultant: "How to Use Shell command for DOS Commands"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
