CodeGuru
Earthweb Search
Forums Wireless Jars Gamelan Developer.com
CodeGuru Navigation
Member Sign In
User ID:
Password:
Remember Me:
Forgot Password?
Not a member?
Click here for more information and to register.

Become a Marketplace Partner

jobs.internet.com

internet.commerce
Partners & Affiliates
















RSS Feeds

RSSAll

RSSVC++/C++

RSS.NET/C#

RSSVB

See more EarthWeb Network feeds

Home >> Visual C++ / C++ >> Miscellaneous >> Miscellaneous


Redirect Output of CMD.EXE to a Pipe
Rating: none

Xinhai Kang (view profile)
April 4, 1999

Environment: Visual C++ 6.0 SP2, Windows NT 4.0 SP4
(continued)



I have the thought of redirecting output of WIN32 console programs to a pipe or a file long ago, but I don't know to do at all at first, finally I searched through Microsoft MSDN and found a way, the code pasted below was copied from MSDN sample code except some changes in function CreateChildProcess(), where I stressed in the code.

In the demo source, I redirect the stdout of CMD.exe to a pipe and start a thread to read from this pipe, then all that CMD.EXE output was redirected to the pipe where I am reading.



BOOL CShellView::CreateShellRedirect()
{
SECURITY_ATTRIBUTES saAttr;
BOOL fSuccess;

// Set the bInheritHandle flag so pipe handles are inherited.
saAttr.nLength = sizeof(SECURITY_ATTRIBUTES);
saAttr.bInheritHandle = TRUE;
saAttr.lpSecurityDescriptor = NULL;

// The steps for redirecting child process's STDOUT:
// 1. Save current STDOUT, to be restored later.
// 2. Create anonymous pipe to be STDOUT for child process.
// 3. Set STDOUT of the parent process to be write handle to
// the pipe, so it is inherited by the child process.
// 4. Create a noninheritable duplicate of the read handle and
// close the inheritable read handle.

// Save the handle to the current STDOUT.
hSaveStdout = GetStdHandle(STD_OUTPUT_HANDLE);

// Create a pipe for the child process's STDOUT.
if( !CreatePipe( &hChildStdoutRd, &hChildStdoutWr, &saAttr, 0) )
{
TRACE0( _T("Stdout pipe creation failed\n") );
return FALSE;
}

// Set a write handle to the pipe to be STDOUT.
if( !SetStdHandle(STD_OUTPUT_HANDLE, hChildStdoutWr) )
{
TRACE0( _T("Redirecting STDOUT failed\n") );
return FALSE;
}

// Create noninheritable read handle and close the inheritable read handle.
fSuccess = DuplicateHandle( GetCurrentProcess(), hChildStdoutRd,
GetCurrentProcess(), &hChildStdoutRdDup ,
0, FALSE,
DUPLICATE_SAME_ACCESS );
if( !fSuccess )
{
TRACE0( _T("DuplicateHandle failed\n") );
return FALSE;
}
CloseHandle( hChildStdoutRd );

// The steps for redirecting child process's STDIN:
// 1. Save current STDIN, to be restored later.
// 2. Create anonymous pipe to be STDIN for child process.
// 3. Set STDIN of the parent to be the read handle to the
// pipe, so it is inherited by the child process.
// 4. Create a noninheritable duplicate of the write handle,
// and close the inheritable write handle.

// Save the handle to the current STDIN.
hSaveStdin = GetStdHandle(STD_INPUT_HANDLE);

// Create a pipe for the child process's STDIN.
if( !CreatePipe(&hChildStdinRd, &hChildStdinWr, &saAttr, 0) )
{
TRACE0( _T("Stdin pipe creation failed\n") );
return FALSE;
}
// Set a read handle to the pipe to be STDIN.
if( !SetStdHandle(STD_INPUT_HANDLE, hChildStdinRd) )
{
TRACE0( _T("Redirecting Stdin failed\n") );
return FALSE;
}
// Duplicate the write handle to the pipe so it is not inherited.
fSuccess = DuplicateHandle(GetCurrentProcess(), hChildStdinWr,
GetCurrentProcess(), &hChildStdinWrDup,
0, FALSE, // not inherited
DUPLICATE_SAME_ACCESS );
if( !fSuccess )
{
TRACE0( _T("DuplicateHandle failed\n") );
return FALSE;
}
CloseHandle(hChildStdinWr);

// Now create the child process.
if( !CreateChildProcess(dwProcessId) )
{
TRACE0( _T("CreateChildProcess failed\n") );
return FALSE;
}
// After process creation, restore the saved STDIN and STDOUT.
if( !SetStdHandle(STD_INPUT_HANDLE, hSaveStdin) )
{
TRACE0( _T("Re-redirecting Stdin failed\n") );
return FALSE;
}
if( !SetStdHandle(STD_OUTPUT_HANDLE, hSaveStdout) )
{
TRACE0( _T("Re-redirecting Stdout failed\n") );
return FALSE;
}
m_pReadThread =
fxBeginThread( (AFX_THREADPROC)ReadPipeThreadProc,(LPVOID)this );
if( !m_pReadThread )
{
TRACE0( _T("Cannot start read-redirect thread!\n") );
return FALSE;
}
return TRUE;
}

BOOL CShellView::CreateChildProcess(DWORD& dwProcessId)
{
PROCESS_INFORMATION piProcInfo;
STARTUPINFO siStartInfo;

// Set up members of STARTUPINFO structure.
ZeroMemory( &siStartInfo, sizeof(STARTUPINFO) );
siStartInfo.cb = sizeof(STARTUPINFO);
/////////////////////////////////////////
/*
Note here the
dwFlags should be STARTF_USESTDHANDLES, which is descripted in WIN32 API
document, but this was
omitted in MSDN sample
*/
siStartInfo.dwFlags = STARTF_USESTDHANDLES;
siStartInfo.hStdInput = hChildStdinRd;
siStartInfo.hStdOutput = hChildStdoutWr;
siStartInfo.hStdError = hChildStdoutWr;

///////////////////////////////////////////////////
TCHAR shellCmd[_MAX_PATH];
if( !GetEnvironmentVariable(_T("ComSpec"), shellCmd, _MAX_PATH) )
return FALSE;
#ifdef _UNICODE
_tcscat( shellCmd, _T(" /U") );
#else
_tcscat( shellCmd, _T(" /A") );
#endif
// Create the child process.
BOOL ret = CreateProcess( NULL,
shellCmd, // applicatin name
NULL, // process security attributes
NULL, // primary thread security attributes
TRUE, // handles are inherited
DETACHED_PROCESS, // creation flags
NULL, // use parent's environment
NULL, // use parent's current directory
&siStartInfo, // STARTUPINFO pointer
&piProcInfo); // receives PROCESS_INFORMATION
if( ret )
dwProcessId = piProcInfo.dwProcessId;
return ret;
}

Download source - 5 KB

Date Last Updated: April 4, 1999

Tools:
Add www.codeguru.com to your favorites
Add www.codeguru.com to your browser search box
IE 7 | Firefox 2.0 | Firefox 1.5.x
Receive news via our XML/RSS feed







RATE THIS ARTICLE:   Excellent  Very Good  Average  Below Average  Poor  

(You must be signed in to rank an article. Not a member? Click here to register)

Latest Comments:
A new easier method of Redirecting Standard I/O - JeredGNU (03/04/2008)
reading output that process that has completed? - Legacy CodeGuru (10/23/2003)
pop up a console window - Legacy CodeGuru (02/28/2003)
Works for Win9x and WinNT now - Legacy CodeGuru (10/21/2002)
Redirect Output of CMD.EXE to a Pipe - Legacy CodeGuru (08/27/2002)

View All Comments
Add a Comment:
Title:
Comment:
Pre-Formatted: Check this if you want the text to display with the formatting as typed (good for source code)



(You must be signed in to comment on an article. Not a member? Click here to register)


JupiterOnlineMedia

internet.comearthweb.comDevx.commediabistro.comGraphics.com

Search:

Jupitermedia Corporation has two divisions: Jupiterimages and JupiterOnlineMedia

Jupitermedia Corporate Info


Legal Notices, Licensing, Reprints, & Permissions, Privacy Policy.

Advertise | Newsletters | Tech Jobs | Shopping | E-mail Offers

Solutions
Whitepapers and eBooks
IBM Whitepaper: Innovative Collaboration to Advance Your Business
Internet.com eBook: Real Life Rails
Avaya Article: Call Control XML - Powerful, Standards-Based Call Control
Tripwire Whitepaper: Seven Practical Steps to Mitigate Virtualization Security Risks
Internet.com eBook: The Pros and Cons of Outsourcing
Go Parallel Article: Scalable Parallelism with Intel(R) Threading Building Blocks
Internet.com eBook: Best Practices for Developing a Web Site
IBM CXO Whitepaper: The 2008 Global CEO Study "The Enterprise of the Future"
Avaya Article: Call Control XML in Action - A CCXML Auto Attendant
Go Parallel Article: James Reinders on the Intel Parallel Studio Beta Program
IBM CXO Whitepaper: Unlocking the DNA of the Adaptable Workforce--The Global Human Capital Study 2008
Adobe Acrobat Connect Pro: Web Conferencing and eLearning Whitepapers
Go Parallel Article: Getting Started with TBB on Windows
HP eBook: Storage Networking , Part 1
MORE WHITEPAPERS, EBOOKS, AND ARTICLES
Webcasts
Go Parallel Video: Intel(R) Threading Building Blocks: A New Method for Threading in C++
HP Video: Is Your Data Center Ready for a Real World Disaster?
Microsoft Partner Portal Video: Microsoft Gold Certified Partners Build Successful Practices
HP On Demand Webcast: Virtualization in Action
Go Parallel Video: Performance and Threading Tools for Game Developers
Rackspace Hosting Center: Customer Videos
Intel vPro Developer Virtual Bootcamp
HP Disaster-Proof Solutions eSeminar
HP On Demand Webcast: Discover the Benefits of Virtualization
MORE WEBCASTS, PODCASTS, AND VIDEOS
Downloads and eKits
Microsoft Download: Silverlight 2 Software Development Kit Beta 2
30-Day Trial: SPAMfighter Exchange Module
Red Gate Download: SQL Toolbelt
Iron Speed Designer Application Generator
Microsoft Download: Silverlight 2 Beta 2 Runtime
MORE DOWNLOADS, EKITS, AND FREE TRIALS
Tutorials and Demos
IBM IT Innovation Article: Green Servers Provide a Competitive Advantage
Microsoft Article: Expression Web 2 for PHP Developers--Simplify Your PHP Applications
Featured Algorithm: Intel Threading Building Blocks - parallel_reduce
MORE TUTORIALS, DEMOS AND STEP-BY-STEP GUIDES