I've written a Windows service in C# using the ServiceBase
helper. During its execution, some procedures in an external native DLL are called. Annoyingly, those procedures write to stdout and/or stderr in an uncontrolled manner as no sources are given for this DLL.
Is it possible to redirect those outputs from the C# service to a log file?
Understanding the concept of redirections and file descriptors is very important when working on the command line. To redirect stderr and stdout , use the 2>&1 or &> constructs.
The I/O streams can be redirected by putting the n> operator in use, where n is the file descriptor number. For redirecting stdout, we use “1>” and for stderr, “2>” is added as an operator. We have created a file named “sample. txt” to store the redirected output in our current directory.
The regular output is sent to Standard Out (STDOUT) and the error messages are sent to Standard Error (STDERR). When you redirect console output using the > symbol, you are only redirecting STDOUT. In order to redirect STDERR, you have to specify 2> for the redirection symbol.
You can do this via PInvoke to SetStdHandle:
[DllImport("Kernel32.dll", SetLastError = true) ]
public static extern int SetStdHandle(int device, IntPtr handle);
// in your service, dispose on shutdown..
FileStream filestream;
StreamWriter streamwriter;
void Redirect()
{
int status;
IntPtr handle;
filestream = new FileStream("logfile.txt", FileMode.Create);
streamwriter = new StreamWriter(filestream);
streamwriter.AutoFlush = true;
Console.SetOut(streamwriter);
Console.SetError(streamwriter);
handle = filestream.Handle;
status = SetStdHandle(-11, handle); // set stdout
// Check status as needed
status = SetStdHandle(-12, handle); // set stderr
// Check status as needed
}
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With