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I am using NSTask to pipe data through a command, the code is like this:

@implementation NSData (AsyncWrite)

The code is sort of okay, the problem arise when a command doesn’t read from standard in, and there is a lot of data (probably > 8KB), then I get an exception from writeData:, I do catch this exception (i.e. my [[NSLog is invoked), but my program will hang afterwards. It hangs in the readDataToEndOfFile selector.

Okay, I have sort of solved the problem – despite the exception, I also get a SIGPIPE ( and it seems the default handler for this signal is ‘broken’ (in that it makes my app hang), so I install my own handler using:

signal(SIGPIPE, BrokenPipeHandler);


why don’t you try reading in background?

Because the code which fails is the code which write to the task – furthermore, it would complicate my program design a great deal, since the program should be “blocked” while waiting for the result of the NSTask.

id outputPipe=[NSPipe pipe];
taskOutputHandle=[outputPipe fileHandleForReading];  // taskOutputHandle is an instance variable
[yourTask setStandardOutput:outputPipe];
[outputHandle readInBackgroundAndNotify];

-(void)methodThatRespondsToNSFileHandleDataAvailableNotification:(id)sender { if (taskOutputHandle==sender) { blah, blah, blah……. } }

-(id)init { … [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(methodThatRespondsToNSFileHandleDataAvailableNotification:) name:NSFileHandleDataAvailableNotification object:nil]; … }

-(void)dealloc { [[NSNotificationCenter defaultCenter] removeObserver:self]; [super dealloc]; }