I am writing a regular compiled application that needs to create a special file and write a magic cookie into it. I can’t write the file directly from the application, the system security model requires me to launch a helper tool with elevated privileges to do the trick. I can supply any number of arguments to the helper tool. Now I would like to pick some very simple system command that would serve as the helper tool and create the file for me. Something like this:
/bin/sh -c "/bin/echo -n 'magic' > /some/where/file"
touch does not cut it as I need to write the cookie into the file, a simple
echo without the shell wrapper does not work as it needs redirection to write the file. I don’t feel comfortable calling the shell with root privileges to do such a trivial task. Is there some really simple, constrained system command that I could call to write the file for me?