Perry said:

Also be especially careful about how you run the thing! Don't use popen or anything like it!

There's nothing inherently wrong with using popen or system. The problem arises when you use information given to you from outside as the argument to popen or system without checking it. You should have an awareness that whatever you pass to system or popen is essentially being passed as the commandstring to a: execl("/bin/sh", "sh", "-c", commandstring, (char *)0); Make sure you know the implications of this. If you know that what you're passing can happily be exec'd directly, it's more efficient to do an exec yourself instead of (effectively) having a sh exec'd to exec your code. Of course you can see that you shouldn't do something like: cout << "Enter the directory to list: " cin >> buffer; system(buffer); especially if you're running with any sort of priviledges. Suppose someone entered: / ; echo >>/etc/passwd "gotcha::0:0:Intruder Man:/:/sbin/sh Obviously if this program was being run as root you'd be in trouble. If it was running as a user it would let them do something like add an .rhosts for the user that would let them get on the machine. Once on a machine it's often fairly easy to leverage that access into root access. Oh well, I could talk about security all day:) Patrick _______________________________________________________________________ / These opinions are mine, and not Verity's (except by coincidence;). \ | (\ | | Patrick J. Horgan Verity Inc. \\ Have | | patrick@verity.com 1550 Plymouth Street \\ _ Sword | | Phone : (415)960-7600 Mountain View \\/ Will | | FAX : (415)960-7750 California 94303 _/\\ Travel | \___________________________________________________________\)__________/