shell_exec() question

what i would like to do is shell_exec('cd /etc/tinydns/stuff/root/data;./tinydns-data') works fine on the command line but not this way i have to cd to the directory because i need to be in the same directory as tinydns-data which opens a data file in that directory. I got around it by putting those commands in a shell script and shell_exec() the shell script but it would be nice to do it without the two line shell script