Support macOS with Homebrew gnu-getopt

Author: aimileus

src/zfs-auto-snapshot.sh

@@ -207,7 +207,13 @@ do_snapshots () # properties, flags, snapname, oldglob, [targets...]
 # main ()
 # {
 
-GETOPT=$(getopt \
+if [ "$(uname)" == "Darwin" ]; then
+  GETOPT_BIN="$(brew --prefix gnu-getopt 2> /dev/null || echo /usr/local)/bin/getopt"
+else
+  GETOPT_BIN="getopt"
+fi
+
+GETOPT=$($GETOPT_BIN \
   --longoptions=default-exclude,dry-run,fast,skip-scrub,recursive \
   --longoptions=event:,keep:,label:,prefix:,sep: \
   --longoptions=debug,help,quiet,syslog,verbose \
@@ -536,7 +542,7 @@ SNAPPROP="-o com.sun:auto-snapshot-desc='$opt_event'"
 
 # ISO style date; fifteen characters: YYYY-MM-DD-HHMM
 # On Solaris %H%M expands to 12h34.
-DATE=$(date --utc +%F-%H%M)
+DATE=$(date -u +%F-%H%M)
 
 # The snapshot name after the @ symbol.
 SNAPNAME="$opt_prefix${opt_label:+$opt_sep$opt_label}-$DATE"