diff --git a/libexec/pyenv b/libexec/pyenv
index bd929254..05955aa7 100755
--- a/libexec/pyenv
+++ b/libexec/pyenv
@@ -1,9 +1,25 @@
 #!/usr/bin/env bash
 set -e
-[ -n "$PYENV_DEBUG" ] && set -x
+export -n CDPATH
+
+if [ "$1" = "--debug" ]; then
+  export PYENV_DEBUG=1
+  shift
+fi
+
+if [ -n "$PYENV_DEBUG" ]; then
+  export PS4='+ [${BASH_SOURCE##*/}:${LINENO}] '
+  set -x
+fi
+
+READLINK=$(type -p greadlink readlink | head -1)
+if [ -z "$READLINK" ]; then
+  echo "pyenv: cannot find readlink - are you missing GNU coreutils?" >&2
+  exit 1
+fi
 
 resolve_link() {
-  $(type -p greadlink readlink | head -1) "$1"
+  $READLINK "$1"
 }
 
 abs_dirname() {
diff --git a/libexec/pyenv---version b/libexec/pyenv---version
index 8efa55bf..f1247e7d 100755
--- a/libexec/pyenv---version
+++ b/libexec/pyenv---version
@@ -14,8 +14,9 @@ set -e
 
 version="0.4.0-20131217"
 
-cd "$PYENV_ROOT"
-git_revision="$(git describe --tags HEAD 2>/dev/null || true)"
-git_revision="${git_revision#v}"
+if cd "$PYENV_ROOT" 2>/dev/null; then
+  git_revision="$(git describe --tags HEAD 2>/dev/null || true)"
+  git_revision="${git_revision#v}"
+fi
 
 echo "pyenv ${git_revision:-$version}"
diff --git a/libexec/pyenv-exec b/libexec/pyenv-exec
index 57fa0865..677bd738 100755
--- a/libexec/pyenv-exec
+++ b/libexec/pyenv-exec
@@ -7,11 +7,11 @@
 # Runs an executable by first preparing PATH so that the selected Python
 # version's `bin' directory is at the front.
 #
-# For example, if the currently selected Python version is 2.7.7:
+# For example, if the currently selected Python version is 2.7.6:
 #   pyenv exec pip install -rrequirements.txt
 #
 # is equivalent to:
-#   PATH="$PYENV_ROOT/versions/2.7.7/bin:$PATH" pip install -rrequirements.txt
+#   PATH="$PYENV_ROOT/versions/2.7.6/bin:$PATH" pip install -rrequirements.txt
 
 set -e
 [ -n "$PYENV_DEBUG" ] && set -x
@@ -21,7 +21,7 @@ if [ "$1" = "--complete" ]; then
   exec pyenv shims --short
 fi
 
-export PYENV_VERSION="$(pyenv-version-name)"
+PYENV_VERSION="$(pyenv-version-name)"
 PYENV_COMMAND="$1"
 
 if [ -z "$PYENV_COMMAND" ]; then
@@ -29,10 +29,14 @@ if [ -z "$PYENV_COMMAND" ]; then
   exit 1
 fi
 
+export PYENV_VERSION
 PYENV_COMMAND_PATH="$(pyenv-which "$PYENV_COMMAND")"
 PYENV_BIN_PATH="${PYENV_COMMAND_PATH%/*}"
 
-for script in $(pyenv-hooks exec); do
+OLDIFS="$IFS"
+IFS=$'\n' scripts=(`rbenv-hooks exec`)
+IFS="$OLDIFS"
+for script in "${scripts[@]}"; do
   source "$script"
 done
 
diff --git a/libexec/pyenv-hooks b/libexec/pyenv-hooks
index 8394138b..bd6572ae 100755
--- a/libexec/pyenv-hooks
+++ b/libexec/pyenv-hooks
@@ -19,13 +19,18 @@ if [ -z "$PYENV_COMMAND" ]; then
   exit 1
 fi
 
+READLINK=$(type -p greadlink readlink | head -1)
+if [ -z "$READLINK" ]; then
+  echo "pyenv: cannot find readlink - are you missing GNU coreutils?" >&2
+  exit 1
+fi
+
 resolve_link() {
-  $(type -p greadlink readlink | head -1) $1
+  $READLINK "$1"
 }
 
 realpath() {
   local cwd="$(pwd)"
-  local base="$(basename $1)"
   local path="$1"
 
   while [ -n "$path" ]; do
@@ -34,13 +39,15 @@ realpath() {
     path="$(resolve_link "$name" || true)"
   done
 
-  echo "$(pwd)/$base"
+  echo "$(pwd)/$name"
   cd "$cwd"
 }
 
+IFS=: hook_paths=($PYENV_HOOK_PATH)
+
 shopt -s nullglob
-for path in ${PYENV_HOOK_PATH//:/$'\n'}; do
-  for script in $path/"$PYENV_COMMAND"/*.bash; do
+for path in "${hook_paths[@]}"; do
+  for script in "$path/$PYENV_COMMAND"/*.bash; do
     echo $(realpath $script)
   done
 done
diff --git a/libexec/pyenv-rehash b/libexec/pyenv-rehash
index a1f5b03b..5b758ae5 100755
--- a/libexec/pyenv-rehash
+++ b/libexec/pyenv-rehash
@@ -17,7 +17,11 @@ mkdir -p "$SHIM_PATH"
 set -o noclobber
 { echo > "$PROTOTYPE_SHIM_PATH"
 } 2>/dev/null ||
-{ echo "pyenv: cannot rehash: $PROTOTYPE_SHIM_PATH exists"
+{ if [ -w "$SHIM_PATH" ]; then
+    echo "pyenv: cannot rehash: $PROTOTYPE_SHIM_PATH exists"
+  else
+    echo "pyenv: cannot rehash: $SHIM_PATH isn't writable"
+  fi
   exit 1
 } >&2
 set +o noclobber
@@ -78,9 +82,9 @@ remove_outdated_shims() {
 # registered for installation as a shim. In this way, plugins may call
 # `make_shims` with a glob to register many shims at once.
 make_shims() {
-  local shims="$@"
+  local shims=("$@")
 
-  for file in $shims; do
+  for file in "${shims[@]}"; do
     local shim="${file##*/}"
     register_shim "$shim"
   done
@@ -92,7 +96,7 @@ registered_shims=()
 registered_shims_index=""
 
 # We will keep track of shims registered for installation with the
-# global `reigstered_shims` array and with a global search index
+# global `registered_shims` array and with a global search index
 # string. The array will let us iterate over all registered shims. The
 # index string will let us quickly check whether a shim with the given
 # name has been registered or not.
@@ -140,7 +144,11 @@ make_shims ../versions/*/bin/*
 cd "$OLDPWD"
 
 # Allow plugins to register shims.
-for script in $(pyenv-hooks rehash); do
+OLDIFS="$IFS"
+IFS=$'\n' scripts=(`pyenv-hooks rehash`)
+IFS="$OLDIFS"
+
+for script in "${scripts[@]}"; do
   source "$script"
 done
 
diff --git a/libexec/pyenv-sh-shell b/libexec/pyenv-sh-shell
index 1e9f5667..e02383f9 100755
--- a/libexec/pyenv-sh-shell
+++ b/libexec/pyenv-sh-shell
@@ -51,14 +51,14 @@ fi
 # Make sure the specified version is installed.
 if pyenv-prefix "${versions[@]}" >/dev/null; then
   OLDIFS="$IFS"
-  IFS=: PYENV_VERSION="${versions[*]}"
+  IFS=: version="${versions[*]}"
   IFS="$OLDIFS"
   case "$shell" in
   fish )
-    echo "setenv PYENV_VERSION \"${PYENV_VERSION}\""
+    echo "setenv PYENV_VERSION \"${version}\""
     ;;
   * )
-    echo "export PYENV_VERSION=\"${PYENV_VERSION}\""
+    echo "export PYENV_VERSION=\"${version}\""
     ;;
   esac
 else
diff --git a/libexec/pyenv-shims b/libexec/pyenv-shims
index 3aae3caf..43c6308a 100755
--- a/libexec/pyenv-shims
+++ b/libexec/pyenv-shims
@@ -11,6 +11,8 @@ if [ "$1" = "--complete" ]; then
   exit
 fi
 
+shopt -s nullglob
+
 for command in "${PYENV_ROOT}/shims/"*; do
   if [ "$1" = "--short" ]; then
     echo "${command##*/}"
diff --git a/libexec/pyenv-version-file-read b/libexec/pyenv-version-file-read
index c5d5a435..d3325646 100755
--- a/libexec/pyenv-version-file-read
+++ b/libexec/pyenv-version-file-read
@@ -8,14 +8,8 @@ VERSION_FILE="$1"
 if [ -e "$VERSION_FILE" ]; then
   # Read the first non-whitespace word from the specified version file.
   # Be careful not to load it whole in case there's something crazy in it.
-  versions=()
-  while read -a words; do
-    word="${words[0]}"
-    if [ -n "$word" ]; then
-      length="${#versions[@]}"
-      versions=("${versions[@]}" "$word")
-    fi
-  done < <( cat "$VERSION_FILE" && echo )
+  words=( $(cut -b 1-1024 "$VERSION_FILE") )
+  versions=("${words[@]}")
 
   if [ -n "$versions" ]; then
     OLDIFS="$IFS"
diff --git a/libexec/pyenv-version-name b/libexec/pyenv-version-name
index ceb047fb..fcc06765 100755
--- a/libexec/pyenv-version-name
+++ b/libexec/pyenv-version-name
@@ -3,20 +3,20 @@
 set -e
 [ -n "$PYENV_DEBUG" ] && set -x
 
-if [ -n "$PYENV_VERSION" ]; then
-  OLDIFS="$IFS"
-  IFS=: versions=($(echo "${PYENV_VERSION}"))
-  IFS="$IFS"
-else
+if [ -z "$PYENV_VERSION" ]; then
   PYENV_VERSION_FILE="$(pyenv-version-file)"
   OLDIFS="$IFS"
   IFS=: versions=($(pyenv-version-file-read "$PYENV_VERSION_FILE" || true))
   IFS=: PYENV_VERSION="${versions[*]}"
   IFS="$OLDIFS"
   export PYENV_VERSION
+else
+  OLDIFS="$IFS"
+  IFS=: versions=($(echo "${PYENV_VERSION}"))
+  IFS="$IFS"
 fi
 
-if [ -z "$versions" ]; then
+if [ -z "$versions" ] || [ "$versions" = "system" ]; then
   echo "system"
   exit
 fi
diff --git a/libexec/pyenv-versions b/libexec/pyenv-versions
index 4434cc1b..03bbac1d 100755
--- a/libexec/pyenv-versions
+++ b/libexec/pyenv-versions
@@ -34,9 +34,9 @@ array_exists() {
 
 print_version() {
   if array_exists "$1" "${current_versions[@]}"; then
-    echo "${hit_prefix}${1}${version_origin}"
+    echo "${hit_prefix}$1${version_origin}"
   else
-    echo "${miss_prefix}${1}"
+    echo "${miss_prefix}$1"
   fi
 }
 
diff --git a/libexec/pyenv-which b/libexec/pyenv-which
index 82da05e8..8e2a6f4e 100755
--- a/libexec/pyenv-which
+++ b/libexec/pyenv-which
@@ -36,9 +36,7 @@ remove_from_path() {
   fi
 
   local paths
-  OLDIFS="$IFS"
   IFS=: paths=($PATH)
-  IFS="$OLDIFS"
 
   for path in "${paths[@]}"; do
     path="$(expand_path "$path" || true)"
@@ -73,7 +71,10 @@ for version in "${versions[@]}"; do
   fi
 done
 
-for script in $(pyenv-hooks which); do
+OLDIFS="$IFS"
+IFS=$'\n' scripts=(`pyenv-hooks which`)
+IFS="$OLDIFS"
+for script in "${scripts[@]}"; do
   source "$script"
 done