diff --git a/LICENSE b/LICENSE
index a10a977..7122f41 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright 2021 Andrew Walsh
+Copyright 2022 Andrew Walsh
 
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
diff --git a/install_and_cache_pkgs.sh b/install_and_cache_pkgs.sh
index 2e7bc04..c0a30cc 100755
--- a/install_and_cache_pkgs.sh
+++ b/install_and_cache_pkgs.sh
@@ -7,9 +7,6 @@ set -e
 script_dir="$(dirname -- "$(realpath -- "${0}")")"
 source "${script_dir}/lib.sh"
 
-# Install apt-fast for optimized installs.
-/bin/bash -c "$(curl -sL https://git.io/vokNn)"
-
 # Directory that holds the cached packages.
 cache_dir="${1}"
 
@@ -24,10 +21,14 @@ log "Clean installing and caching ${package_count} package(s)."
 
 log_empty_line
 
+manifest_main=""
 log "Package list:"
 for package in ${normalized_packages}; do
-  log "- ${package}"
+  read package_name package_ver < <(get_package_name_ver "${package}")
+  manifest_main="${manifest_main}${package_name}:${package_ver},"  
+  log "- ${package_name}:${package_ver}"
 done
+write_manifest "main" "${manifest_main}" "${cache_dir}/manifest_main.log"
 
 log_empty_line
 
@@ -42,51 +43,35 @@ manifest_main=""
 # Contains all packages including dependencies.
 manifest_all=""
 
-log "Gathering install information for ${package_count} packages..."
-log_empty_line
-cached_packages=""
-for package in ${normalized_packages}; do
-  read package_name package_ver < <(get_package_name_ver "${package}")    
-
-  # Comma delimited name:ver pairs in the main requested packages manifest.
-  manifest_main="${manifest_main}${package_name}:${package_ver},"
-
-  cached_packages="${cached_packages} ${package_name}:${package_version}"
-  read dep_packages < <(get_dep_packages "${package_name}")
-  cached_packages="${cached_packages} $(echo ${dep_packages} | tr '\n' ' ')"
-
-  if test -z "${dep_packages}"; then
-    dep_packages_text="none";
-  else
-    dep_packages_text="${dep_packages}"
-  fi
-
-  log "- ${package_name}"
-  log "  * Version: ${package_ver}"
-  log "  * Dependencies: ${dep_packages_text}"
-  log_empty_line
-done
-log "done"
-
-log_empty_line
+install_log_filepath="${cache_dir}/install.log"
 
 log "Clean installing ${package_count} packages..."
 # Zero interaction while installing or upgrading the system via apt.
-sudo DEBIAN_FRONTEND=noninteractive apt-fast --yes install ${normalized_packages} > /dev/null
+sudo DEBIAN_FRONTEND=noninteractive apt-fast --yes install ${normalized_packages} > "${install_log_filepath}"
 log "done"
+log "Installation log written to ${install_log_filepath}"
 
 log_empty_line
 
-cached_package_count=$(wc -w <<< "${cached_packages}")
-log "Caching ${cached_package_count} installed packages..."
-for cached_package in ${cached_packages}; do
-  cache_filepath="${cache_dir}/${cached_package}.tar.gz"
+installed_packages=$(get_installed_packages "${install_log_filepath}")
+log "Installed package list:"
+for installed_package in ${installed_packages}; do
+  log "- ${installed_package}"
+done
 
+log_empty_line
+
+installed_package_count=$(wc -w <<< "${installed_packages}")
+log "Caching ${installed_package_count} installed packages..."
+for installed_package in ${installed_packages}; do
+  cache_filepath="${cache_dir}/${installed_package}.tar.gz"
+
+  # Sanity test in case APT enumerates duplicates.
   if test ! -f "${cache_filepath}"; then
-    read cached_package_name cached_package_ver < <(get_package_name_ver "${cached_package}")
-    log "  * Caching ${cached_package_name} to ${cache_filepath}..."
+    read installed_package_name installed_package_ver < <(get_package_name_ver "${installed_package}")
+    log "  * Caching ${installed_package_name} to ${cache_filepath}..."
     # Pipe all package files (no folders) to Tar.
-    dpkg -L "${cached_package_name}" |
+    dpkg -L "${installed_package_name}" |
       while IFS= read -r f; do     
         if test -f $f || test -L $f; then echo "${f:1}"; fi;  #${f:1} removes the leading slash that Tar disallows
       done |
@@ -95,11 +80,10 @@ for cached_package in ${cached_packages}; do
   fi
 
   # Comma delimited name:ver pairs in the all packages manifest.
-  manifest_all="${manifest_all}${cached_package_name}:${cached_package_ver},"
+  manifest_all="${manifest_all}${installed_package_name}:${installed_package_ver},"
 done
 log "done (total cache size $(du -h ${cache_dir} | tail -1 | awk '{print $1}'))"
 
 log_empty_line
 
 write_manifest "all" "${manifest_all}" "${cache_dir}/manifest_all.log"
-write_manifest "main" "${manifest_main}" "${cache_dir}/manifest_main.log"
diff --git a/lib.sh b/lib.sh
index edabb1a..0aedaee 100755
--- a/lib.sh
+++ b/lib.sh
@@ -9,15 +9,28 @@ function normalize_package_list {
   echo "${sorted}"  
 }
 
-# Gets a package list of dependencies as newline delimited pairs
-#   <name>:<version>\n<name:version>...
-function get_dep_packages {  
-  echo $(apt-fast install --dry-run --yes "${1}" | \
-    grep "^Inst" | sort | awk '{print $2 $3}' | \
-    tr '(' ':' | grep -v "${1}:")
+# Gets a list of installed packages as space delimited pairs with each pair colon delimited.
+#   <name>:<version> <name:version>...
+function get_installed_packages {   
+  install_log_filepath="${1}"
+  local regex="^Unpacking ([^ :]+)([^ ]+)? (\[[^ ]+\]\s)?\(([^ )]+)"  
+  dep_packages=""  
+  while read -r line; do
+    if [[ "${line}" =~ ${regex} ]]; then
+      dep_packages="${dep_packages}${BASH_REMATCH[1]}:${BASH_REMATCH[4]} "      
+    else
+      log_err "Unable to parse package name and version from \"${line}\""
+      exit 2
+    fi
+  done < <(grep "^Unpacking " ${install_log_filepath})
+  if test -n "${dep_packages}"; then
+    echo "${dep_packages:0:-1}"  # Removing trailing space.
+  else
+    echo ""
+  fi
 }
 
-# Split fully qualified package into name and version
+# Split fully qualified package into name and version.
 function get_package_name_ver {
   IFS=\: read name ver <<< "${1}"
   # If version not found in the fully qualified package value.
@@ -28,13 +41,16 @@ function get_package_name_ver {
 }
 
 function log { echo "$(date +%H:%M:%S)" "${@}"; }
+function log_err { >&2 echo "$(date +%H:%M:%S)" "${@}"; }
 
 function log_empty_line { echo ""; }
 
 # Writes the manifest to a specified file.
 function write_manifest {
   log "Writing ${1} packages manifest to ${3}..."  
-  # 0:-1 to remove trailing comma, delimit by newline and sort
+  # 0:-1 to remove trailing comma, delimit by newline and sort.
   echo "${2:0:-1}" | tr ',' '\n' | sort > ${3}
   log "done"
 }
+
+get_installed_packages "/tmp/cache-apt-pkgs-action-cache/install.log"
diff --git a/pre_cache_action.sh b/pre_cache_action.sh
index b6755ed..c2fe2d6 100755
--- a/pre_cache_action.sh
+++ b/pre_cache_action.sh
@@ -19,7 +19,7 @@ packages="$(normalize_package_list "${input_packages}")"
 # Create cache directory so artifacts can be saved.
 mkdir -p ${cache_dir}
 
-log -n "Validating action arguments (version='${version}', packages='${packages}')...";
+log "Validating action arguments (version='${version}', packages='${packages}')...";
 if grep -q " " <<< "${version}"; then
   log "aborted" 
   log "Version value '${version}' cannot contain spaces." >&2
@@ -32,14 +32,22 @@ if test -z "${packages}"; then
   log "Packages argument cannot be empty." >&2
   exit 2
 fi
+
+log "done"
+
+log_empty_line
+
+log "Installing apt-fast for optimized installs..."
+# Install apt-fast for optimized installs.
+/bin/bash -c "$(curl -sL https://git.io/vokNn)"
 log "done"
 
 log_empty_line
 
 versioned_packages=""
-log -n "Verifying packages..."
+log "Verifying packages..."
 for package in ${packages}; do 
-  if test ! "$(apt show "${package}")"; then
+  if test ! "$(apt-cache show "${package}")"; then
     echo "aborted"
     log "Package '${package}' not found." >&2
     exit 3
@@ -47,7 +55,7 @@ for package in ${packages}; do
   read package_name package_ver < <(get_package_name_ver "${package}")
   versioned_packages=""${versioned_packages}" "${package_name}"="${package_ver}""
 done
-echo "done"
+log "done"
 
 log_empty_line