Fix pool exclusions.

Use $ZPOOL_STATUS instead of $ZFS_STATUS for pool exclusions.

A mistaken variable name made the pool exclusion logic a no-op and
broke the --skip-scrub switch.

Also correct a trivial comment typo.

README

@@ -1,4 +1,12 @@
-An alternative implementation of the zfs-auto-snapshot service for Linux.
+zfs-auto-snapshot:
+
+An alternative implementation of the zfs-auto-snapshot service for Linux
+that is compatible with zfs-linux and zfs-fuse.
+
+Automatically create, rotate, and destroy periodic ZFS snapshots. This is
+the utility that creates the @zfs-auto-snap_frequent, @zfs-auto-snap_hourly,
+@zfs-auto-snap_daily, @zfs-auto-snap_weekly, and @zfs-auto-snap_monthly
+snapshots if it is installed.
 
 This program is a posixly correct bourne shell script.  It depends only on
 the zfs utilities and cron, and can run in the dash shell.

src/zfs-auto-snapshot.sh

@@ -358,13 +358,13 @@ do
 done
 
 # Get a list of pools that are being scrubbed.
-ZPOOLS_SCRUBBING=$(echo "$ZFS_STATUS" | awk -F ': ' \
+ZPOOLS_SCRUBBING=$(echo "$ZPOOL_STATUS" | awk -F ': ' \
   '$1 ~ /^ *pool$/ { pool = $2 } ; \
    $1 ~ /^ *scan$/ && $2 ~ /scrub in progress/ { print pool }' \
   | sort ) 
 
 # Get a list of pools that cannot do a snapshot.
-ZPOOLS_NOTREADY=$(echo "$ZFS_STATUS" | awk -F ': ' \
+ZPOOLS_NOTREADY=$(echo "$ZPOOL_STATUS" | awk -F ': ' \
   '$1 ~ /^ *pool$/ { pool = $2 } ; \
    $1 ~ /^ *state$/ && $2 !~ /ONLINE|DEGRADED/ { print pool } ' \
   | sort)
@@ -446,7 +446,7 @@ do
 		# Ibid regarding iii.
 		jjj="$jj/"
 
-		# The --recusive switch only matters for non-wild arguments.
+		# The --recursive switch only matters for non-wild arguments.
 		if [ -z "$opt_recursive" -a "$1" != '//' ]
 		then
 			# Snapshot this dataset non-recursively.