NSTask launch

    NSTask *task = [[NSTask alloc] init];
    [task setLaunchPath: @"/usr/bin/grep"];
    [task setArguments: @[ @"foo", @"bar.txt"]];

    NSPipe *pipe = [NSPipe pipe];
    [task setStandardOutput: pipe];

    [task launch];

    NSFileHandle *file = [pipe fileHandleForReading];
    NSString *string = [[NSString alloc] initWithData: [file readDataToEndOfFile]
                                             encoding: NSUTF8StringEncoding];
    NSLog (@"grep returned:\n%@", string);