iphone redirect shell command

I am 开发者_如何转开发working on an jail broken iphone app that calls a shell command. To read the output I redirect the output of the command to file. That is where my problem lies. When I attempt to do the redirect sh reports that the operation is not permitted.this is the exact output of gdb: sh: ./tmp/tmp.out: Operation not permitted Also I call my command using the system() function. thank you in advance

You might instead want to use NSTask which is built for these sorts of things.