simplify customization of envvars

zfssnap.sh

@@ -1,13 +1,20 @@
 #! /bin/sh
 
+# change this to the name of your ZFS pool.
+zpool="zroot"
+
+# names of the DATASETs to exclude (datasets, not mountpoints!)
+# can override this list at runtime with EXCLUDES envvar.
+# can extend this list at runtime with EXTRA_EXCLUDES envvar.
+excludes="/usr/ports /usr/src /backups"
+
+
+# You do not want to edit anything below here
+
 tstamp=`date +%Y%m%d-%H%M%S`
 label_pfx="zbk-"
 usrlabel=$1
 maxnum=$2
-zpool="zroot"
-
-# names of the DATASETs to exclude (datasets, not mountpoints!)
-excludes="/usr/ports /usr/src /backups"
 
 usage () {
     echo Usage: