$ strace -o <command>.trace -e trace=file <command>
$ grep ^open <command>.trace | grep -v '= -1' | cut -d\" -f2 | sort -u
'lsof' (List Open Files) is a good choice for this task. It will show you files and ports in use.
sudo lsof | grep <command>
Thanks! lsof is good at having a snap shot while strace is good to create a complete list :)