Cocoa wrapper for an interactive Unix command - objective-c

Question

Ok, so I know you can make an NSTask to run command line tools with Objective-C:
NSTask *task;
task = [[NSTask alloc] init];
[task setLaunchPath: #"/usr/bin/gdb"];
[task launch];
I'm just wondering if there's a way to communicate with interactive command line tools such a as gdb. This would involve giving the command inputs based on user interaction (like run, kill or quit with gdb) and then reacting based on the information it outputs.

Answer 1

You can use NSTask's setStandardInput:, setStandardOutput: and setStandardError: selectors in conjunction with NSPipe instances to communicate with the launched program.
For example, to read the task's output:
task = [[NSTask alloc] init];
[task setStandardOutput: [NSPipe pipe]];
[task setStandardError: [task standardOutput]]; // Get standard error output too
[task setLaunchPath: #"/usr/bin/gdb"];
[task launch];
You can then obtain an NSFileHandle instance that you can use to read the task's output with:
NSFileHandle *readFromMe = [[task standardOutput] fileHandleForReading];
To set up a pipe for sending commands to gdb, you would add
[task setStandardInput: [NSPipe pipe]];
before you launch the task. Then you get the NSFileHandle with
NSFileHandle *writeToMe = [[task standardInput] fileHandleForWriting];

Answer 2

Use setStandardInput: and setStandardOutput: methods of NSTaks class.
NSTask *task;
task = [[NSTask alloc] init];
[task setLaunchPath: #"/usr/bin/gdb"];
NSPipe *outputpipe=[[NSPipe alloc]init];
NSPipe *errorpipe=[[NSPipe alloc]init];
NSFileHandle *output,*error;
[task setArguments: arguments];
[task setStandardOutput:outputpipe];
[task setStandardError:errorpipe];
NSLog(#"%#",arguments);
output=[outputpipe fileHandleForReading];
error=[errorpipe fileHandleForReading];
[task launch];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(receivedData:) name: NSFileHandleReadCompletionNotification object:output];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(receivedError:) name: NSFileHandleReadCompletionNotification object:error];
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(TaskCompletion:) name: NSTaskDidTerminateNotification object:task];
//[input writeData:[NSMutableData initWithString:#"test"]];
[output readInBackgroundAndNotify];
[error readInBackgroundAndNotify];
[task waitUntilExit];
[outputpipe release];
[errorpipe release];
[task release];
-(void) receivedData:(NSNotification*) rec_not {
NSFileHandle *out=[[task standardOutput] fileHandleForReading];
NSData *dataOutput=[[rec_not userInfo] objectForKey:NSFileHandleNotificationDataItem];
if( !dataOutput)
NSLog(#">>>>>>>>>>>>>>Empty Data");
NSString *strfromdata=[[NSString alloc] initWithData:dataOutput encoding:NSUTF8StringEncoding];
[out readInBackgroundAndNotify];
[strfromdata release];
}
/* Called when there is some data in the error pipe */
-(void) receivedError:(NSNotification*) rec_not {
NSFileHandle *err=[[task standardError] fileHandleForReading];
NSData *dataOutput=[[rec_not userInfo] objectForKey:NSFileHandleNotificationDataItem];
if( !dataOutput)
NSLog(#">>>>>>>>>>>>>>Empty Data");
else {
NSString *strfromdata=[[NSString alloc] initWithData:dataOutput encoding:NSUTF8StringEncoding];
[strfromdata release];
}
[err readInBackgroundAndNotify];
}
/* Called when the task is complete */
-(void) TaskCompletion :(NSNotification*) rec_not {
NSLog(#"task ended");
}