cmd: move single-file binaries up, extract udev programs to udev/

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13316

cmd/fsck.zfs.in

@@ -0,0 +1,44 @@
+#!/bin/sh
+#
+# fsck.zfs: A fsck helper to accommodate distributions that expect
+# to be able to execute a fsck on all filesystem types.
+#
+# This script simply bubbles up some already-known-about errors,
+# see fsck.zfs(8)
+#
+
+if [ $# -eq 0 ]; then
+	echo "Usage: $0 [options] dataset…" >&2
+	exit 16
+fi
+
+ret=0
+for dataset; do
+	case "$dataset" in
+		-*)
+			continue
+			;;
+		*)
+			;;
+	esac
+
+	pool="${dataset%%/*}"
+
+	case "$(@sbindir@/zpool list -Ho health "$pool")" in
+		DEGRADED)
+			ret=$(( ret | 4 ))
+			;;
+		FAULTED)
+			awk '!/^([[:space:]]*#.*)?$/ && $1 == "'"$dataset"'" && $3 == "zfs" {exit 1}' /etc/fstab || \
+				ret=$(( ret | 8 ))
+			;;
+		"")
+			# Pool not found, error printed by zpool(8)
+			ret=$(( ret | 8 ))
+			;;
+		*)
+			;;
+	esac
+done
+
+exit "$ret"