diff --git a/apt_info.py b/apt_info.py
index 90f2b52..1945591 100755
--- a/apt_info.py
+++ b/apt_info.py
@@ -1,24 +1,26 @@
 #!/usr/bin/env python3
-#
-# Description: Expose metrics from apt. This is inspired by and
-# intended to be a replacement for the original apt.sh.
-#
-# This script deliberately does *not* update the apt cache. You need
-# something else to run `apt update` regularly for the metrics to be
-# up to date. This can be done in numerous ways, but the canonical way
-# is to use the normal `APT::Periodic::Update-Package-Lists`
-# setting.
-#
-# This, for example, will enable a nightly job that runs `apt update`:
-#
-#     echo 'APT::Periodic::Update-Package-Lists "1";' > /etc/apt/apt.conf.d/99_auto_apt_update.conf
-#
-# See /usr/lib/apt/apt.systemd.daily for details.
-#
-# Dependencies: python3-apt, python3-prometheus-client
-#
-# Authors: Kyle Fazzari <kyrofa@ubuntu.com>
-#          Daniel Swarbrick <dswarbrick@debian.org>
+
+"""
+Description: Expose metrics from apt. This is inspired by and
+intended to be a replacement for the original apt.sh.
+
+This script deliberately does *not* update the apt cache. You need
+something else to run `apt update` regularly for the metrics to be
+up to date. This can be done in numerous ways, but the canonical way
+is to use the normal `APT::Periodic::Update-Package-Lists`
+setting.
+
+This, for example, will enable a nightly job that runs `apt update`:
+
+    echo 'APT::Periodic::Update-Package-Lists "1";' > /etc/apt/apt.conf.d/99_auto_apt_update.conf
+
+See /usr/lib/apt/apt.systemd.daily for details.
+
+Dependencies: python3-apt, python3-prometheus-client
+
+Authors: Kyle Fazzari <kyrofa@ubuntu.com>
+         Daniel Swarbrick <dswarbrick@debian.org>
+"""
 
 import apt
 import apt_pkg
@@ -88,13 +90,16 @@ def _write_autoremove_pending(registry, cache):
 def _write_cache_timestamps(registry):
     g = Gauge('apt_package_cache_timestamp_seconds', "Apt update last run time.", registry=registry)
     apt_pkg.init_config()
-    if apt_pkg.config.find_b("APT::Periodic::Update-Package-Lists"):
+    if (
+        apt_pkg.config.find_b("APT::Periodic::Update-Package-Lists") and
+        os.path.isfile("/var/lib/apt/periodic/update-success-stamp")
+    ):
         # if we run updates automatically with APT::Periodic, we can
-        # check this timestamp file
+        # check this timestamp file if it exists
         stamp_file = "/var/lib/apt/periodic/update-success-stamp"
     else:
-        # if not, let's just fallback on the lists directory
-        stamp_file = '/var/lib/apt/lists'
+        # if not, let's just fallback on the partial file of the lists directory
+        stamp_file = '/var/lib/apt/lists/partial'
     try:
         g.set(os.stat(stamp_file).st_mtime)
     except OSError:
diff --git a/directory-size.sh b/directory-size.sh
index 3e03f04..5357901 100755
--- a/directory-size.sh
+++ b/directory-size.sh
@@ -13,4 +13,4 @@
 echo "# HELP node_directory_size_bytes Disk space used by some directories"
 echo "# TYPE node_directory_size_bytes gauge"
 du --block-size=1 --summarize "$@" \
-  | sed -ne 's/\\/\\\\/;s/"/\\"/g;s/^\([0-9]\+\)\t\(.*\)$/node_directory_size_bytes{directory="\2"} \1/p'
+  | awk '{ print "node_directory_size_bytes{directory=\"" $2 "\"} "  $1 }'
diff --git a/yum.sh b/yum.sh
index f30143f..ce06b97 100755
--- a/yum.sh
+++ b/yum.sh
@@ -32,17 +32,17 @@ upgrades=$(check_upgrades)
 
 echo '# HELP yum_upgrades_pending Yum package pending updates by origin.'
 echo '# TYPE yum_upgrades_pending gauge'
-if [[ -n "${upgrades}" ]] ; then
+if [[ -n "${upgrades}" ]]; then
   echo "${upgrades}"
 else
   echo 'yum_upgrades_pending{origin=""} 0'
 fi
 
 # If yum-utils/dnf-utils is not installed then we skip rendering this metric
-if [[ -x /bin/needs-restarting ]] ; then
+if [[ -x /bin/needs-restarting ]]; then
   echo '# HELP node_reboot_required Node reboot is required for software updates.'
   echo '# TYPE node_reboot_required gauge'
-  if /bin/needs-restarting -r  > /dev/null 2>&1 ; then
+  if /bin/needs-restarting -r >/dev/null 2>&1; then
     echo 'node_reboot_required 0'
   else
     echo 'node_reboot_required 1'