debugfs command not found

There is no debugfs(8) on Mac OS X. Debugfs(8) is a Linux program used to debug the Linux file system ext2/ext3. If you want to debug a Mac filesystem like HFS+ try fsck(8) or use Disk Utility.

If you really want to debug a Linux ext2/ext3 filesystem on a Mac (e.g. an external Linux USB disk) you will have to install ext2/3 first. Since you have /opt/local/bin in your path I suppose you have MacPorts installed. In this case you could just install the packet ext2fuse which includes the debugfs(8) program.

You can install e2fsprogs, including debugfs, using Homebrew on OsX.

brew install e2fsprogs

You will find debugfs in /usr/local/opt/e2fsprogs/sbin/debugfs