dtrace/dtruss command to see what files a command tries to open? Is there a dtrace one liner that will run a command, and tell me all the files it tries to open?

The Linux strace equivalent of what I'm trying to do is strace -e trace=file -f cat /etc/passwd &gt; /dev/null

I am on El Capitan
You may want to try iosnoop.  See here: http://dtrace.org/blogs/brendan/2011/10/10/top-10-dtrace-scripts-for-mac-os-x/

It's been a long time since I used it; the Sierra/High Sierra equivalent is fs_usage, so maybe you have access to that too.  Also if you install Homebrew (brew.sh), you can download and install many command-line utilities not already present in the OS.