Protect some shell expansions and do a general tidy up.

Heavily inspired by a PR from @mvk

puppet-ls

@@ -1,5 +1,5 @@
 #!/bin/bash
-# tested on 0.25
+# tested on 0.25 and 3.8.4
 
 usage () {
 
@@ -39,12 +39,12 @@ exit 0
 #################################################################
 
 appname=$(basename "$0")
-comm="comm -12"
+comm='comm -12'
 
-while getopts "irRh" option
+while getopts 'irRh' option
 do
 case $option in
-    i ) comm="comm -13" ;;
+    i ) comm='comm -13' ;;
     r ) recursive=1 ;;
     R ) follow_links=1 ;;
     h ) usage ;;
@@ -53,7 +53,7 @@ case $option in
 done
 
 # grab the non-getopts option
-shift $(($OPTIND - 1))
+shift $((OPTIND - 1))
 target="${1-$(pwd)}"
 target="${target%/}"
 
@@ -72,8 +72,8 @@ else
   vardir='/var/lib/puppet'
 fi
 
-catalog_filelist=$(mktemp -q /tmp/$appname.XXXXXX)
-lister_filelist=$(mktemp -q /tmp/$appname.XXXXXX)
+catalog_filelist=$(mktemp -q "/tmp/$appname.XXXXXX")
+lister_filelist=$(mktemp -q "/tmp/$appname.XXXXXX")
 
 # better clean up
 trap "rm -f $catalog_filelist $lister_filelist" 0 1 2 15
@@ -82,8 +82,8 @@ trap "rm -f $catalog_filelist $lister_filelist" 0 1 2 15
 (
   grep -h "title: /" "$vardir/state/last_run_report.yaml" | awk '{ print $NF }' ;
   sed -e '/File\[/!d' -e 's/File\[//' -e 's/\]://' -e 's/ //g' < /var/lib/puppet/state/state.yaml
-) | sort > $catalog_filelist
+) | sort > "$catalog_filelist"
 
-$lister | sort > $lister_filelist
+$lister | sort > "$lister_filelist"
 
-$comm $catalog_filelist $lister_filelist
+$comm "$catalog_filelist" "$lister_filelist"