//命令原型：sh -c "echo 密码 | su -c 'ls --help' "

                //转载请注明：http://www.cnblogs.com/bandy/p/7069503.html

                NSTask *task = [NSTask new];

                [task setLaunchPath:@"/bin/sh"];

                [task setArguments:[NSArray arrayWithObjects:@"-c", @"/bin/echo alpine | /bin/su -c '/bin/ls --help' ", nil]];

                NSPipe *pipe = [NSPipe pipe];

                [task setStandardOutput:pipe];

                [task launch];

                NSData *data = [[pipe fileHandleForReading] readDataToEndOfFile];

                [task waitUntilExit];

                NSString * string;

                string = [[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding];//root

                NSLog(@"Result: %@", string);

                //转载请注明：http://www.cnblogs.com/bandy/p/7069503.html