The question, as written, has no answer. fsck only checks the filesystem. There is no way to check the consistency of the running kernel but a kernel panic is a telltale sign of INconsistency :)
You can check the consistency of the kernel "file" and compare a MD5 / SHA-1 of known good kernel. Assumption here that the kernel is loaded into healthy hardware. Depends on the spirit of the question. I do agree, running kernel looking at itself... chicken::egg.
I was very confused on this question as well. Seeing both kernel and filesystem there together with the word consistent made me think of a sort of general health. So my answer would have been `iostat`. That would show me the running kernel, cpu utilization, and disk utilization.
I presume 'not much' or 'you get an error', but I don't have an instance I'm prepared to sacrifice right now, just in case something hilariously destructive happens.
fsck doesn't run on a directory, it runs on a block device. You can't run it on /proc or /sys because those aren't backed by a block device. /proc only looks like it has a file system because the kernel "pulls" the "files" out of thin air when you try to access them.
