diff --git a/README.md b/README.md
index 927e93a..972ce8a 100644
--- a/README.md
+++ b/README.md
@@ -24,8 +24,8 @@ Create a workflow `.yml` file in your repositories `.github/workflows` directory
 ### Outputs
 
 * `cache-hit` - A boolean value to indicate a cache was found for the packages requested.
-* `package-version-list` - The packages and versions that are installed as a comma delimited list with colon delimit on the package version (i.e. \<package1>:<version1\>,\<package2>:\<version2>,...).
-  
+* `package-version-list` - The main requested packages and versions that are installed. Represented as a comma delimited list with colon delimit on the package version (i.e. \<package1>:<version1\>,\<package2>:\<version2>,...).
+* `all-package-version-list` - All the pulled in packages and versions, including dependencies, that are installed. Represented as a comma delimited list with colon delimit on the package version (i.e. \<package1>:<version1\>,\<package2>:\<version2>,...).
 
 ### Cache scopes
 
diff --git a/action.yml b/action.yml
index 3ef2f6a..9cd2164 100644
--- a/action.yml
+++ b/action.yml
@@ -26,7 +26,10 @@ outputs:
     # Need to output true and false instead of true and nothing.
     value: ${{ steps.load-cache.outputs.cache-hit || false }}
   package-version-list:
-    description: 'The packages and versions that are installed as a comma delimited list with colon delimit on the package version (i.e. <package>:<version,<package>:<version>).'
+    description: 'The main requested packages and versions that are installed. Represented as a comma delimited list with colon delimit on the package version (i.e. <package>:<version,<package>:<version>).'
+    value: ${{ steps.post-cache.outputs.package-version-list }}
+  all-package-version-list:
+    description: 'All the pulled in packages and versions, including dependencies, that are installed. Represented as a comma delimited list with colon delimit on the package version (i.e. <package>:<version,<package>:<version>).'
     value: ${{ steps.post-cache.outputs.package-version-list }}
 
 runs:
@@ -54,5 +57,6 @@ runs:
           / \
           "${{ steps.load-cache.outputs.cache-hit }}" \
           ${{ inputs.packages }}
-        echo "::set-output name=package-version-list::$(cat ~/cache-apt-pkgs/manifest.log)"
+        echo "::set-output name=package-version-list::$(cat ~/cache-apt-pkgs/manifest_main.log)"
+        echo "::set-output name=all-package-version-list::$(cat ~/cache-apt-pkgs/manifest_all.log)"
       shell: bash
diff --git a/install_and_cache_pkgs.sh b/install_and_cache_pkgs.sh
index 4de889d..467f980 100755
--- a/install_and_cache_pkgs.sh
+++ b/install_and_cache_pkgs.sh
@@ -7,45 +7,78 @@ set -e
 cache_dir=$1
 
 # List of the packages to use.
-packages="${@:2}"
+input_packages="${@:2}"
 
-package_count=$(echo $packages | wc -w)
-echo "Clean installing and caching $package_count package(s)."
-echo "Package list:"
-for package in $packages; do
-  echo "- $package"
+# Trim commas, excess spaces, and sort.
+normalized_packages="$(normalize_package_list "${input_packages}")"
+
+package_count=$(wc -w <<< "${normalized_packages}")
+log "Clean installing and caching ${package_count} package(s)."
+log "Package list:"
+for package in ${normalized_packages}; do
+  log "- ${package}"
 done
 
-echo -n "Updating APT package list..."
+log "Updating APT package list..."
 sudo apt-get update > /dev/null
 echo "done."
 
-echo "Clean installing and caching $(echo $packages | wc -w) packages..."
-for package in $packages; do
-  cache_filepath=$cache_dir/$package.tar.gz
+# Strictly contains the requested packages.
+manifest_main=""
+# Contains all packages including dependencies.
+manifest_all=""
 
-  echo "- $package"
-  echo -n "  Installing..."
-  sudo apt-get --yes install $package > /dev/null
+log "Clean installing and caching ${package_count} 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}:${package_ver},"
+
+  all_packages="$(apt-get install --dry-run --yes "${package_name}" | grep "^Inst" | awk '{print $2}')"
+  dep_packages="$(echo ${all_packages} | grep -v "${package_name}" | tr '\n' ,)"
+  if "${dep_packages}" == ","; then
+    dep_packages="none";
+  fi
+
+  log "- ${package_name}"
+  log "  * Version: ${package_ver}"
+  log "  * Dependencies: ${dep_packages}"
+  log "  * Installing..."
+  # Zero interaction while installing or upgrading the system via apt.
+  sudo DEBIAN_FRONTEND=noninteractive apt-get --yes install "${package}" > /dev/null
   echo "done."
 
-  echo -n "  Caching to $cache_filepath..."
-  # Pipe all package files (no folders) to Tar.
-  dpkg -L $package |
-    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 | 
-    xargs tar -czf $cache_filepath -C /    
-  echo "done."
+  for cache_package in ${all_packages}; do
+    cache_filepath="${cache_dir}/${cache_package}.tar.gz"
+
+    if test ! -f "${cache_filepath}"; then
+      read cache_package_name cache_package_ver < <(get_package_name_ver "${cache_package}")
+      log "  * Caching ${cache_package_name} to ${cache_filepath}..."
+      # Pipe all package files (no folders) to Tar.
+      dpkg -L "${cache_package_name}" |
+        while IFS= read -r f; do     
+          if test -f $f || test -L $f; then echo "${f:1}"; fi;  #${f:1} removes the leading slash that Tar disallows
+        done | 
+        xargs tar -czf "${cache_filepath}" -C /      
+      log "done (compressed size $(du -k "${cache_filepath}" | cut -f1))."
+    fi
+
+    # Comma delimited name:ver pairs in the all packages manifest.
+    manifest_all="${manifest_all}${cache_package_name}:${cache_package_ver},"
+  done  
 done
-echo "done."
+log "done."
+
+manifest_all_filepath="${cache_dir}/manifest_all.log"
+log "Writing all packages manifest to ${manifest_all_filepath}..."
+# Remove trailing comma and write to manifest_all file.
+echo "${manifest_all:0:-1}" > "${manifest_all_filepath}"
+log "done."
+
+manifest_main_filepath="${cache_dir}/manifest_main.log"
+log "Writing main requested packages manifest to ${manifest_main_filepath}..."
+# Remove trailing comma and write to manifest_main file.
+echo "${manifest_main:0:-1}" > "${manifest_main_filepath}"
+log "done."
 
-manifest_filepath="$cache_dir/manifest.log"
-echo -n "Writing package manifest to $manifest_filepath..."
-manifest=
-for package in $packages; do
-  manifest=$manifest$package:$(dpkg -s $package | grep Version | awk '{print $2}'),
-done  
-# Remove trailing comma.
-echo ${manifest:0:-1} > $manifest_filepath
-echo "done."
diff --git a/lib.sh b/lib.sh
new file mode 100755
index 0000000..f3757c9
--- /dev/null
+++ b/lib.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+
+# Sort these packages by name and split on commas.
+function normalize_package_list {
+  local stripped=$(echo "${1}" | sed 's/,//g')
+  # Remove extraneous spaces at the middle, beginning, and end.
+  local trimmed="$(echo "${stripped}" | sed 's/\s\+/ /g; s/^\s\+//g; s/\s\+$//g')"
+  local sorted="$(echo ${trimmed} | tr ' ' '\n' | sort | tr '\n' ' ')"
+  echo "${sorted}"  
+}
+
+# Split fully qualified package into name and version
+function get_package_name_ver {
+  IFS=\= read name ver <<< "${1}"
+  # If version not found in the fully qualified package value.
+  if test -z "${ver}"; then
+    ver="$(grep "Version:" <<< "$(apt show ${name})" | awk '{print $2}')"
+  fi
+  echo "${name}" "${ver}"
+}
+
+function log { echo "$(date +%H:%M:%S)" "${@}"; }
\ No newline at end of file
diff --git a/post_cache_action.sh b/post_cache_action.sh
index 5503013..144fe76 100755
--- a/post_cache_action.sh
+++ b/post_cache_action.sh
@@ -3,24 +3,28 @@
 # Fail on any error.
 set -e
 
+# Include library.
+script_dir="$(dirname -- "$(realpath -- "${0}")")"
+source "${script_dir}/lib.sh"
+
 # Directory that holds the cached packages.
-cache_dir=$1
+cache_dir="${1}"
 
 # Root directory to untar the cached packages to.
 # Typically filesystem root '/' but can be changed for testing.
-cache_restore_root=$2
+cache_restore_root="${2}"
 
 # Indicates that the cache was found.
-cache_hit=$3
+cache_hit="${3}"
 
 # List of the packages to use.
 packages="${@:4}"
 
-script_dir=$(dirname $0)
+script_dir="$(dirname -- "$(realpath -- "${0}")")"
 
 if [ "$cache_hit" == true ]; then
-  $script_dir/restore_pkgs.sh ~/cache-apt-pkgs $cache_restore_root
+  ${script_dir}/restore_pkgs.sh ~/cache-apt-pkgs "${cache_restore_root}"
 else
-  $script_dir/install_and_cache_pkgs.sh ~/cache-apt-pkgs $packages
+  ${script_dir}/install_and_cache_pkgs.sh ~/cache-apt-pkgs ${packages}
 fi
 echo ""
diff --git a/pre_cache_action.sh b/pre_cache_action.sh
index ba09879..7921adb 100755
--- a/pre_cache_action.sh
+++ b/pre_cache_action.sh
@@ -1,60 +1,69 @@
 #!/bin/bash
 
+# Include library.
+script_dir="$(dirname -- "$(realpath -- "${0}")")"
+source "${script_dir}/lib.sh"
+
 # Directory that holds the cached packages.
-cache_dir=$1
+cache_dir="${1}"
 
 # Version of the cache to create or load.
-version=$2
+version="${2}"
 
 # List of the packages to use.
-packages=${@:3}
+input_packages="${@:3}"
+
+# Trim commas, excess spaces, and sort.
+packages="$(normalize_package_list "${input_packages}")"
 
 # Create cache directory so artifacts can be saved.
-mkdir -p $cache_dir
+mkdir -p ${cache_dir}
 
-echo -n "Validating action arguments (version='$version', packages='$packages')...";
-echo $version | grep -o " " > /dev/null
-if [ $? -eq 0 ]; then
-  echo "aborted."
-  echo "Version value '$version' cannot contain spaces." >&2
+log -n "Validating action arguments (version='${version}', packages='${packages}')...";
+if grep -q " " <<< "${version}"; then
+  log "aborted." 
+  log "Version value '${version}' cannot contain spaces." >&2
   exit 1
 fi
-if [ "$packages" == "" ]; then
-  echo "aborted."
-  echo "Packages argument cannot be empty." >&2
+
+# Is length of string zero?
+if test -z "${packages}"; then
+  log "aborted."
+  log "Packages argument cannot be empty." >&2
   exit 2
 fi
-echo "done."
+log "done."
 
-echo -n "Verifying packages..."
-for package in $packages; do
-  escaped=$(echo $package | sed 's/+/\\+/g')
-  apt-cache search ^$escaped$ | grep $package > /dev/null
-  if [ $? -ne 0 ]; then
+versioned_packages=""
+log -n "Verifying packages..."
+for package in ${packages}; do 
+  if test ! "$(apt show "${package}")"; then
     echo "aborted."
-    echo "Package '$package' not found." >&2
+    log "Package '${package}' not found." >&2
     exit 3
   fi
+  read package_name package_ver < <(get_package_name_ver "${package}")
+  versioned_packages=""${versioned_packages}" "${package_name}"="${package_ver}""
 done
 echo "done."
 
 # Abort on any failure at this point.
 set -e
 
-echo "Creating cache key..."
+log "Creating cache key..."
 
-# Remove package delimiters, sort (requires newline) and then convert back to inline list.
-normalized_list=$(echo $packages | sed 's/[\s,]+/ /g' | tr ' ' '\n' | sort | tr '\n' ' ')
-echo "- Normalized package list is '$normalized_list'."
+# TODO Can we prove this will happen again?
+normalized_versioned_packages="$(normalize_package_list "${versioned_packages}")"
+log "- Normalized package list is '${normalized_versioned_packages}'."
 
-value=$(echo $normalized_list @ $version)
-echo "- Value to hash is '$value'."
+value="${normalized_versioned_packages} @ ${version}"
+log "- Value to hash is '${value}'."
 
-key=$(echo $value | md5sum | cut -f1 -d' ')
-echo "- Value hashed as '$key'."
+key="$(echo "${value}" | md5sum | /bin/cut -f1 -d' ')"
+log "- Value hashed as '${key}'."
 
-echo "done."
+log "done."
 
-key_filepath="$cache_dir/cache_key.md5"
-echo $key > $key_filepath
-echo "Hash value written to $key_filepath"
+key_filepath="${cache_dir}/cache_key.md5"
+echo ${key} > ${key_filepath}
+log "Hash value written to ${key_filepath}"
diff --git a/restore_pkgs.sh b/restore_pkgs.sh
index ab87879..ec6c475 100755
--- a/restore_pkgs.sh
+++ b/restore_pkgs.sh
@@ -3,32 +3,36 @@
 # Fail on any error.
 set -e
 
+# Include library.
+script_dir="$(dirname -- "$(realpath -- "${0}")")"
+source "${script_dir}/lib.sh"
+
 # Directory that holds the cached packages.
-cache_dir=$1
+cache_dir="${1}"
 
 # Root directory to untar the cached packages to.
 # Typically filesystem root '/' but can be changed for testing.
-cache_restore_root=$2
+cache_restore_root="${2}"
 
-cache_filepaths=$(ls -1 $cache_dir | sort)
-echo "Found $(echo $cache_filepaths | wc -w) files in the cache."
-for cache_filepath in $cache_filepaths; do
-  echo "- $(basename $cache_filepath)"
+cache_filepaths="$(ls -1 "${cache_dir}" | sort)"
+log "Found $(echo ${cache_filepaths} | wc -w) files in the cache."
+for cache_filepath in ${cache_filepaths}; do
+  log "- "$(basename ${cache_filepath})""
 done
 
-echo "Reading from manifest..."
-for logline in $(cat $cache_dir/manifest.log | tr ',' '\n' ); do
-  echo "- $(echo $logline | tr ':' ' ')"
+log "Reading from main requested packages manifest..."
+for logline in $(cat "${cache_dir}/manifest_main.log" | tr ',' '\n' ); do
+  log "- $(echo "${logline}" | tr ':' ' ')"
 done
-echo "done."
+log "done."
 
 # Only search for archived results. Manifest and cache key also live here.
-cache_pkg_filepaths=$(ls -1 $cache_dir/*.tar.gz | sort)
-cache_pkg_filecount=$(echo $cache_pkg_filepaths | wc -w)
-echo "Restoring $cache_pkg_filecount packages from cache..."
-for cache_pkg_filepath in $cache_pkg_filepaths; do
-  echo -n "- $(basename $cache_pkg_filepath) restoring..."
-  sudo tar -xf $cache_pkg_filepath -C $cache_restore_root > /dev/null
-  echo "done."
+cache_pkg_filepaths=$(ls -1 "${cache_dir}"/*.tar.gz | sort)
+cache_pkg_filecount=$(echo ${cache_pkg_filepaths} | wc -w)
+log "Restoring ${cache_pkg_filecount} packages from cache..."
+for cache_pkg_filepath in ${cache_pkg_filepaths}; do
+  log "- $(basename "${cache_pkg_filepath}") restoring..."
+  sudo tar -xf "${cache_pkg_filepath}" -C "${cache_restore_root}" > /dev/null
+  log "done."
 done
-echo "done."
+log "done."